SMSC EMC2105 DATASHEET Revision 1.78 (04-21-09)
Datasheet
PRODUCT FEATURES
EMC2105
RPM-Based High Side Fan
Controller with Hardware
Thermal Shutdown
General Description
The EMC2105 is an SMBus compliant fan controller with
up to five (up to 4 external and 1 internal) temperature
channels. The fan driver can be operated using two
methods each with two modes. The methods include an
RPM based Fan Speed Control Algorithm and a direct
drive setting. The modes include manually programming
the desired settings or using the internal programmable
temperature look-up table to select the desired setting
based on measured temperature.
The temperature monitors offer 1°C accuracy (for
external diodes) with sophisticated features to reduce
errors introduced by series resistance and beta variation
of substrate thermal diode transistors commonly found
in processors.
The EMC2105 also includes a hardware programmable
temperature limit and dedicated system shutdown
output for thermal protection of critical circuitry.
Applications
Notebook Computers
Embedded Applications
Projectors
Industrial and Networking Equipment
Features
Programmable Fan Control circuit
— 600mA, 5V, High Side Fan Driver
— Optional detection of aging fans
RPM based fan control algorithm
— 2% accuracy from 500RPM to 16k RPM
Temperature Look-Up Table
— Allows programmed fan response to temperature
— 1 to 4 thermal zones to control fan driver
— Controls fan speed or drive setting
— Allows externally generated temperature data to control
fan drivers including two DTS channels
Up to Four External Temperature Channels
— Designed to support 45nm, 60nm, and 90nm CPUs
— Automatically detects and supports CPUs requiring the
BJT or Transistor models
— Resistance error correction
— 1°C accurate (60°C to 100°C)
— 0.125°C resolution
— Detects fan aging and variation
Up to three thermistor compatible voltage inputs
Hardware Programmable Thermal Shutdown
Temperature
— Cannot be altered by software
— 60°C to 122°C Range or 92°C to 154°C Range
Programmable High and Low Limits for all channels
3.3V Supply Voltage
SMBus 2.0 Compliant
— SMBus Alert compatible
Available in 20-pin QFN Package - Lead Free RoHS
compliant (4mm x 4mm)
ORDER NUMBER:
REEL SIZE IS 4,000 PIECES
ORDERING NUMBER PACKAGE FEATURES
EMC2105-BP 20 pin QFN Lead-Free
RoHS compliant Single High Side Fan driver, up to 4external
diode measurement channels, one Critical /
Thermal Shutdown input
RPM-Based High Side Fan Controller with Hardware Thermal Shutdown
Datasheet
Revision 1.78 (04-21-09) 2 SMSC EMC2105
DATASHEET
80 ARKAY DRIVE, HAUPPAUGE, NY 11788 (631) 435-6000, FAX (631) 273-3123
Copyright © 2009 SMSC or its subsidiaries. All rights reserved.
Circuit diagrams and other informa tion relating to SMSC products are included as a means of illustrating typical applications. Consequently, complete information sufficient for
construction purposes is not necessarily given. Although the information has been checked and is believed to be accurate, no responsibility is assumed for inaccuracies. SMSC
reserves the right to make changes to specifications and product descriptions at any time without notice. Contact your local SMSC sales office to obtain the latest specifications
before placing your product order. The provision of this information does not convey to the purchaser of the described semiconductor devices any licenses under any patent
rights or other intellectual property rights of SMSC or others. All sales are expressly conditional on your agreement to the terms and conditions of the most recently dated
version of SMSC's standard Terms of Sale Agreement dated before the date of your order (the "Terms of Sale Agreement"). The product may contain design defects or errors
known as anomalies which may cause the product's functions to deviate from published specifications. Anomaly sheets are available upon request. SMSC products are not
designed, intended, authorized or warranted for use in any life support or other application where product failure could cause or contribute to personal injury or severe property
damage. Any and all such uses without prior written approval of an Officer of SMSC and further testing and/or modification will be fully at the risk of the customer. Copies of
this document or other SMSC literature, as well as the Terms of Sale Agreement, may be obtained by visiting SMSC’s website at http://www.smsc.com. SMSC is a registered
trademark of Standard Microsystems Corporation (“SMSC”). Product names and company names are the trademarks of their respective holders.
SMSC DISCLAIMS AND EXCLUDES ANY AND ALL WARRANTIES, INCLUDING WITHOUT LIMITATION ANY AND ALL IMP LIED WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR P URPOSE, TITLE, AND AGAINST INFRINGEMENT AND THE LIKE, AND ANY AND ALL WARRANTIES ARISING FROM ANY COURSE
OF DEALING OR USAGE OF TRADE. IN NO EVENT SHALL SMSC BE LIABLE FOR ANY DIRECT, INCIDENTAL, INDIRECT, SPECIAL, PUNITIVE, OR CONSEQUENTIAL
DAMAGES; OR FOR LOST DATA, PROFITS, SAVINGS OR REVENUES OF ANY KIND; REGARDLESS OF THE FORM OF ACTION, WHETHER BASED ON CONTRACT;
TORT; NEGLIGENCE OF SMSC OR OTHERS ; STRICT LIABILITY; BREACH OF WARRANTY; OR OTHERWISE; WHETHER OR NOT ANY REMEDY OF BUYER IS HELD
TO HAVE FAILED OF ITS E SSENTIAL PURPOSE, AND WHETHER OR NOT SMSC HAS BEEN ADVISE D OF THE POSSIBILITY OF SUCH DAMAGES.
RPM-Based High Side Fan Controller with Hardware Thermal Sh utdown
Datasheet
SMSC EMC2105 3 Revision 1.78 (04-21-09)
DATASHEET
Table of Contents
Chapter 1 Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Chapter 2 Pin Description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Chapter 3 Electrical Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
3.1 Electrical Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
3.2 SMBus Electrical Specifications (client mode) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Chapter 4 Communications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
4.1 System Management Bus Interface Protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
4.2 Write Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
4.3 Read Byte. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
4.4 Send Byte. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
4.5 Receive Byte. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
4.6 Alert Response Address. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
4.7 SMBus Address . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
4.8 SMBus Time-out. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Chapter 5 Product Description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
5.1 Critical/Thermal Shutdown . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
5.1.1 SHDN_SEL Pin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
5.1.2 TRIP_SET / VIN4 Pin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
5.2 Fan Control Modes of Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
5.3 High Side Fan Driver . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
5.3.1 Over Current Limit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
5.4 Fan Control Look-Up Table . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
5.4.1 Programming the Look Up Table. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
5.4.2 DTS Support . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
5.5 RPM based Fan Speed Control Algorithm (FSC). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
5.5.1 Programming the RPM Based Fan Speed Control Algorithm . . . . . . . . . . . . . . . . . . . . . 31
5.6 Tachometer Measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
5.6.1 Stalled Fan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
5.6.2 32kHz Clock Source . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
5.6.3 Aging Fan or Invalid Drive Detection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
5.7 Spin Up Routine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
5.8 Ramp Rate Control. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
5.9 Watchdog Timer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
5.10 Internal Thermal Shutdown (TSD) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
5.11 Fault Queue . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
5.12 Temperature Monitoring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
5.12.1 Dynamic Averaging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
5.12.2 Resistance Error Correction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
5.12.3 Beta Compensation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
5.12.4 Digital Averaging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
5.13 Thermistor Support. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
5.14 Diode Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
5.14.1 Diode Faults . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
5.15 GPIOs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
5.16 Interrupts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
Chapter 6 Register Set. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
RPM-Based High Side Fan Controller with Hardware Thermal Shutdown
Datasheet
Revision 1.78 (04-21-09) 4 SMSC EMC2105
DATASHEET
6.1 Register Map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
6.1.1 Lock Entries. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
6.2 Temperature Data Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
6.3 Critical/Thermal Shutdown Temperature Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
6.4 Pushed Temperature Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
6.5 Voltage Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
6.6 Beta Configuration Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
6.7 REC Configuration Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
6.8 Critical Temperature Limit Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
6.9 Configuration Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
6.10 Configuration 2 Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
6.11 Configuration 3 Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
6.12 Interrupt Status Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
6.13 Error Status Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
6.13.1 Tcrit Status Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
6.14 Fan Status Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
6.15 Interrupt Enable Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
6.16 Fan Interrupt Enable Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
6.17 Limit Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
6.18 Fan Setting Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
6.19 Fan Configuration 1 Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
6.20 Fan Configuration 2 Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
6.21 Gain Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
6.22 Fan Spin Up Configuration Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
6.23 Fan Step Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
6.24 Fan Minimum Drive Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
6.25 Valid TACH Count Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
6.26 Fan Drive Fail Band Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
6.27 TACH Target Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
6.28 TACH Reading Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66
6.29 Look Up Table Configuration Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66
6.30 Look Up Table Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68
6.31 Muxed Pin Configuration Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70
6.32 GPIO Direction Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70
6.33 GPIO Pin Output Configuration Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70
6.34 GPIO Input Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
6.35 GPIO Output Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
6.36 GPIO Interrupt Enable Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
6.37 GPIO Status Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72
6.38 Software Lock Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72
6.39 Product Features Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72
6.40 Product ID Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
6.41 Manufacturer ID Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
6.42 Revision Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
Chapter 7 Package Drawing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74
7.1 QFN 20-Pin 4mm x 4mm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74
7.2 Package Markings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75
Appendix AThermistors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76
A.1 Thermistor Look Up Tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77
Appendix BLook Up Table Operation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
B.1 Example #1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
RPM-Based High Side Fan Controller with Hardware Thermal Sh utdown
Datasheet
SMSC EMC2105 5 Revision 1.78 (04-21-09)
DATASHEET
B.1.1 LUT Configuration Bit Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82
B.2 Example #2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83
B.2.1 Configuration 3 Bit Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84
B.2.2 Fan Configuration 1 Bit Description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84
B.2.3 Fan Spin Up Configuration Bit Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84
B.2.4 LUT Configuration - Bit Description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84
B.3 Example #3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86
B.3.1 Fan Configuration 1 Bit Description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86
B.3.2 Fan Spin Up Configuration Bit Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87
B.3.3 LUT Configuration - Bit Description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87
Chapter 8 Revision History. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89
RPM-Based High Side Fan Controller with Hardware Thermal Shutdown
Datasheet
Revision 1.78 (04-21-09) 6 SMSC EMC2105
DATASHEET
List of Figures
Figure 1.1 EMC2105 Block Diagram. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Figure 2.1 EMC2105 Pin Diagram (20 Pin QFN) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Figure 4.1 SMBus Timing Diagram. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Figure 5.1 System Diagram of EMC2105 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Figure 5.2 EMC2105 Critical/Thermal Shutdown Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Figure 5.3 Fan Control Look-Up Table Example. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Figure 5.4 RPM based Fan Speed Control Algorithm. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Figure 5.5 Spin Up Routine. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Figure 5.6 Ramp Rate Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Figure 5.7 Diode Connections. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
Figure 7.1 EMC2105 20-Pin 4x4mm QFN Package Outline and Parameters . . . . . . . . . . . . . . . . . . . . 74
Figure 7.2 EMC2105 Package Markings. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75
Figure A.1 “Low Side” Thermistor Connection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76
RPM-Based High Side Fan Controller with Hardware Thermal Sh utdown
Datasheet
SMSC EMC2105 7 Revision 1.78 (04-21-09)
DATASHEET
List of Tables
Table 2.1 Pin Description for EMC2105 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Table 2.2 Pin Types. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Table 3.1 Absolute Maximum Ratings. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Table 3.2 Electrical Specifications. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Table 3.3 SMBus Electrical Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Table 4.1 Protocol Format. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Table 4.2 Write Byte Protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Table 4.3 Read Byte Protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Table 4.4 Send Byte Protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Table 4.5 Receive Byte Protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Table 4.6 Alert Response Address Protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Table 5.1 SHDN_SEL Pin Configuration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Table 5.2 TRIP_SET Resistor Setting. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Table 5.3 Fan Controls Active for Operating Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Table 5.4 Dynamic Averaging Behavior . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Table 6.1 EMC2105 Register Set . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
Table 6.2 Temperature Data Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
Table 6.3 Temperature Data Format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
Table 6.4 Critical/Thermal Shutdown Temperature Registers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
Table 6.5 Critical / Thermal Shutdown Data Format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
Table 6.6 Pushed Temperature Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
Table 6.7 TripSet Voltage Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
Table 6.8 Beta Configuration Registers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
Table 6.9 Beta Compensation Look Up Table. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
Table 6.10 REC Configuration Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
Table 6.11 Limit Registers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
Table 6.12 Configuration Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
Table 6.13 Configuration 2 Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
Table 6.14 Fault Queue. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
Table 6.15 Conversion Rate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
Table 6.16 Configuration 3 Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
Table 6.17 Interrupt Status Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
Table 6.18 Error Status Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
Table 6.19 Fan Status Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
Table 6.20 Interrupt Enable Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
Table 6.21 Fan Interrupt Enable Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
Table 6.22 Limit Registers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
Table 6.23 Fan Driver Setting Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
Table 6.24 Fan Configuration 1 Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
Table 6.25 Range Decode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
Table 6.26 Minimum Edges for Fan Rotation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
Table 6.27 Update Time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
Table 6.28 Fan Configuration 1 Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
Table 6.29 Derivative Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
Table 6.30 Error Range Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
Table 6.31 Gain Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
Table 6.32 Gain Decode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
Table 6.33 Fan Spin Up Configuration Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
Table 6.34 DRIVE_FAIL_CNT[1:0] Bit Decode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
Table 6.35 Spin Level . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
Table 6.36 Spin Time. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
Table 6.37 Fan Step Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
Table 6.38 Minimum Fan Drive Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
RPM-Based High Side Fan Controller with Hardware Thermal Shutdown
Datasheet
Revision 1.78 (04-21-09) 8 SMSC EMC2105
DATASHEET
Table 6.39 Valid TACH Count Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
Table 6.40 Fan Drive Fail Band Registers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
Table 6.41 TACH Target Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
Table 6.42 TACH Reading Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66
Table 6.43 Look Up Table Configuration Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66
Table 6.44 TEMP3_CFG Decode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
Table 6.45 TEMP4_CFG Decode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68
Table 6.46 Look Up Table Registers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68
Table 6.47 Muxed Pin Configuration Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70
Table 6.48 GPIO Direction Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70
Table 6.49 GPIO Pin Output Configuration Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70
Table 6.50 GPIO Input Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
Table 6.51 GPIO Output Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
Table 6.52 GPIO Interrupt Enable Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
Table 6.53 GPIO Status Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72
Table 6.54 Software Lock Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72
Table 6.55 Product Features Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72
Table 6.56 SHDN_SEL Bit Decode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
Table 6.57 Product ID Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
Table 6.58 Manufacturer ID Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
Table 6.59 Revision Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
Table A.1 “Low Side” Thermistor Look Up Table. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77
Table A.2 Inverted Thermistor Look Up Table. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79
Table B.1 Look Up Table Format. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
Table B.2 Look Up Table Example #1 Configuration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82
Table B.3 Fan Speed Control Table Example #1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82
Table B.4 Fan Speed Determination for Example #1 (using settings in Table B.3) . . . . . . . . . . . . . . . . . 83
Table B.5 Look Up Table Example #2 Configuration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83
Table B.6 Fan Speed Control Table Example #2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85
Table B.7 Fan Speed Determination for Example #2 (using settings in Table B.6) . . . . . . . . . . . . . . . . . 85
Table B.8 Look Up Table Example #3 Configuration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86
Table B.9 Fan Speed Control Table Example #3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87
Table B.10Fan Speed Determination for Example #3 (using settings in Table B.9) . . . . . . . . . . . . . . . . . 88
Table 8.1 Customer Revision History . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89
RPM-Based High Side Fan Controller with Hardware Thermal Sh utdown
Datasheet
SMSC EMC2105 9 Revision 1.78 (04-21-09)
DATASHEET
Chapter 1 Block Diagram
Figure 1.1 EMC2105 Block Diagram
Analog
Mux
External
Temp
Diodes
Internal
Temp
Diode
11 bit Σ Δ
ADC
Temp Registers
SMBus
Slave
Protocol
Fan
Driver
Configuration
DP1
DN1
SMCLK
SMDATA
Temp Limit
Registers
DP2
DN2
ALERT#
Thermal
Shutdown
Logic
SYS_SHDN#
Tachs
TACH1
Lookup
Table / RPM
Control
CLK_IN*
SHDN_SEL
TRIP_SET*
VDD
GND
VIN1*
* denotes multiple pin functions
VDD_5V
FAN_OUT Reference VREF*
DN4 / DP3*
DP4 / DN3*
VIN2*
GPIO GPIO1*
Anti-
parallel
diode
RPM-Based High Side Fan Controller with Hardware Thermal Shutdown
Datasheet
Revision 1.78 (04-21-09) 10 SMSC EMC2105
DATASHEET
Chapter 2 Pin Description
Figure 2.1 EMC2105 Pin Diagram (20 Pin QFN)
EM C2105
20-QFN
1
2
3
4
6
7
8
9
5
10
15
14
13
12
20
19
18
17
11
16
DN1 / VIN1
DP1 / VREF_T1
TRIP_SET / VIN4
VDD
SMCLK
DN2/ VIN2
DP2 / VREF_T2
SMDATA
ALERT#
SYS_SHDN#
CLK_IN / GPIO1
SHDN_SEL
TACH
GND FAN_OUT
FAN_OUT
VDD_5V
VDD_5V
DN3 / DP4 / VIN3
DP3 / DN4 / VREF_T3
RPM-Based High Side Fan Controller with Hardware Thermal Sh utdown
Datasheet
SMSC EMC2105 11 Revision 1.78 (04-21-09)
DATASHEET
Table 2.1 Pin Description for EMC2105
PIN NUMBER
EMC2105 PIN NAME PIN FUNCTION PIN TYPE
1
DN1 / VIN1
DN1 - Negative (cathode) analog input for
External Diode 1 (default) AIO (2V)
VIN1 - General voltage input for use with
a thermistor AI (2V)
2
DP1 / VREF_T1
DP1 - Positive (anode) analog input for
External Diode 1 (default) AIO (2V)
VREF_T1 - Reference output for us e with
a thermistor and to drive VIN3 AO (2V)
3 GND Ground connection Power
4 VDD Power Supply Power
5ALERT#
Active low interrupt - requires external
pull-up resistor. OD (5V)
6 CLK_IN / GPIO1
CLK_IN - 32.768KHz clock input. DI (5V)
GPI1 - General Purpose Input
(default) DI (5V)
GPO1 - General Purpose push/ pull
Output DI (5V)
GPO1 - General Purpose open drain
Output. DI (5V)
7 SYS_SHDN# Active low Critical System Shutdown
output OD (5V)
8SMDATA
SMBus data input/output - requires
external pull-up resistor DIOD (5V)
9SMCLK
SMBus clock input - requires external
pull-up resistor DIOD (5V)
10 TACH1 Tachometer input for Fan 1 DI (5V)
11 FAN_OUT High Side Fan Driver Output Power
12 FAN_OUT High Side Fan Driver Output Power
13 VDD_5V Supply for High Side Fan Driver Power
14 VDD_5V Supply for High Side Fan Driver Power
15 TRIP_SET / VIN4
TRIP_SET - Determines HW Shutdown
temperature features for the hardware
shutdown channel AI (2V)
VIN4 - General voltage input when
Thermal / Critical shutdown disabled AI (2V)
16 SHDN_SEL Determines HW Shutdown temperature
features and measurement channel AIO
RPM-Based High Side Fan Controller with Hardware Thermal Shutdown
Datasheet
Revision 1.78 (04-21-09) 12 SMSC EMC2105
DATASHEET
The pin type are described in detail below. All pins labelled with (5V) are 5V tolerant.
All pin labelled with (2V) should not be exposed to any voltage level greater than 2V.
17 DN3 / DP4 / VIN3
DN3 / DP4 - Negative (cathode) analog
input for External Diode 3 and positive
(anode) Analog Input for External Diode 4
(default) AIO (2V)
VIN3 - General voltage input for use with
a thermistor AI (2V)
18 DP3 / DN4 / VREF_T3
DP3 / DN4 - Positive (anode) analog input
for External Diode 3 and negative
(cathode) analog input for External Dio de
4
(default)
AIO (2V)
VREF_T3 - Reference output for us e with
a thermistor and to drive VIN3 AIO (2V)
19 DN2 / VIN2
DN2 - Negative (cathode) analog input for
External Diode 2.
(default) AIO (2V)
VIN2 - General voltage input for use with
a thermistor AIO (2V)
20 DP2 / VREF_T2
DP2 - Positive (anode) analog input for
External Diode 2.
(default) AIO (2V)
VREF_T2 - Reference output for us e with
a thermistor and to drive VIN2 AIO (2V)
Table 2.2 Pin Ty pes
PIN TYPE DESCRIPTION
Power This pin is used to supply power or ground to the device.
DI Digital Input - this pin is used a s a digital input. This pin is
5V tolerant.
AI Analog Input - this pin is used as an input for analog
signals.
AO Analog Output - this pin is used as an output for analog
signals.
AIO Analog Input / Output - this pin is used as an I/O for analog
signals.
DO Push / Pull Digital Output - this pin is used as a digital
output. It can both source and sink current.
Table 2.1 Pin Description for EMC2105
PIN NUMBER
EMC2105 PIN NAME PIN FUNCTION PIN TYPE
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DIOD Digital Input / Open Drain Output this pin is used as an
digital I/O. When it is used as an output, It is open drain
and requires a pull-up resistor. This pin is 5V tolerant.
OD Open Drain Digital Output - this pin is used as a digital
output. It is open drain and re quires a pull-up resistor. This
pin is 5V tolerant.
Table 2.2 Pin Types (continued)
PIN TYPE DESCRIPTION
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Chapter 3 Electrical Specifications
Note: Stresses above those listed could cause permanent damage to the device. This is a stress
rating only and functional operation of the device at any other condition above those indicated
in the operation sections of this specification is not implied. When powering this device from
laboratory or system power supplies, it is important that the Absolute Maximum Ratings not be
exceeded or device failure can result. Some power supplies exhibit voltage spikes on their
outputs when the AC power is switched on or off. In addition, voltage transients on the AC
power line may appear on the DC output. If this possibility exists, it is suggested that a clamp
circuit be used.
Note 3.1 All voltages are relative to ground.
Note 3.2 The Package Power Dissipation specification assumes a recommended thermal via design
consisting of four 12mil vias connected to th e grou nd plane wi th a 2x2mm therma l lan ding.
Note 3.3 Junction to Ambi ent (θJA) is dependent on the design of the thermal vias. Without thermal
vias and a thermal landing, the θJA is approximately 52°C/W including localized PCB
temperature increase.
3.1 Electrical Specifications
Table 3.1 Absolute Maximum Ratings
Voltage on 5V tolerant pins including VDD_5V -0.3 to 6.5 V
Voltage on VDD pin -0.3 to 4 V
Voltage on 2V tolerant pins -0.3 to 2.5 V
Voltage on any other pin to GND -0.3 to VDD + 0.3 V
Package Power Dissipation See Note 3.1 1 up to TA = 85°C W
Junction to Ambient (θJA) See Note 3.2 40 °C/W
Operating Ambient Temperature Range -40 to 85°C °C
Storage Temperature Range -55 to 150 °C
ESD Rating, All Pins, HBM 2000 V
Table 3.2 Electrical Specifications
VDD = 3V to 3.6V, VDD_5V = 4.5V to 5.5V, TA = -40°C to 85°C, all Typical values at TA = 27°C unless otherwise
noted.
CHARACTERISTIC SYMBOL MIN TYP MAX UNIT CONDITIONS
DC Power
Supply Voltage VDD 33.33.6V
Supply Current
(active) IDD 2 3 mA 4 Conversions / second -
Dynamic Averaging Enabled
Fan Driver enabled
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Supply Current IDD 500 750 uA 1 Conversions / second-
Dynamic Averaging disabled,
Fan Driver disabled.
Supply Current from
VDD_5V IDD_5 100 uA Fan Driver enabled, No load
current
SMBus Delay tSMB 15 ms Delay from power to first SMBus
communication
Time to First Round
Robin 300 ms
External Temperature Monitors
Temperature
Accuracy ±0.25 ±1 °C 60°C < TDIODE < 110°C
30°C < TDIE < 85°C
±0.5 ±2 °C 0°C < TDIODE < 125°C,
0°C < TDIE < 115°C
Temperature
Resolution 0.125 °C
Diode decoupling
capacitor CFILTER 2200 2700 pF Connected across external
diode, CPU, GPU, or AMD diode
Resistance Error
Corrected RSERIES 100 Ohm Sum of series resistance in both
DP and DN lines
Internal Temperature Monitor
Temperature
Accuracy TDIE ±1 ±2 °C Note 3.4
Temperature
Resolution 0.125 °C
Voltage Measurement
Total Unadjusted
Error TUE 1 % Measured at 3/4 full scale
Reference Voltage VREF 800 mV
Reference Accuracy ΔVREF 1%
High Side Fan Driver
Output High Voltage
from 5V supply VOH_5V VDD_5V
- 0.35 VDD_5
V - 0.3 VI
SOURCE = 600mA, VDD_5V =
5V
Voltage Accuracy ΔVFAN_OUT 1 2 % Measured at 3/4 full scale -
Direct Setting Mode
Fan Drive Current ISOURCE 600 mA
Overcurrent Limit IOVER 2800 mA Momentary Current drive at
startup for < 2 seconds
1.5V < FAN_OUT < 3.5V
Table 3.2 Electrical Specifications (continued)
VDD = 3V to 3.6V, VDD_5V = 4.5V to 5.5V, TA = -40°C to 85°C, all Typical values at TA = 27°C unless otherwise
noted.
CHARACTERISTIC SYMBOL MIN TYP MAX UNIT CONDITIONS
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Note 3.4 TDIE refers to the internal die temperature and may not match TA due to self heating of
the device. The internal temperature sensor will return TDIE.
DC Short Circuit
Current Limit ISHORT 700 mA Sourcing current, Thermal
shutdown not triggered,
FA N_ OU T = 0V
Short circuit delay tDFS 2s
Output Capacitive
Load CLOAD 100 uF ZESR < 100mΩ at 10kHz
RPM Based Fan Controller
Tachometer Range TACH 480 16000 RPM
Tachometer Setting
Accuracy ΔTACH ±1 ±2 % External oscillator 32.768kHz
ΔTACH ±2.5 ±5 % Internal Oscillator
40°C < TDIE < 100°C
Thermal Shutdown
Thermal Shutdown
Threshold TSDTH 150 °C
Thermal Shutdown
Hysteresis TSDHYST 50 °C
Digital I/O pins
Input High Voltage VIH 2.0 V
Input Low Voltage VIL 0.8 V
Output High Voltage VOH VDD -
0.4 V4 mA current drive
Output Low Voltage VOL 0.4 V 4 mA current sink
Leakage current ILEAK ±5 uA ALERT and SYS_SHDN pins
Powered and unpowered
Table 3.2 Electrical Specifications (continued)
VDD = 3V to 3.6V, VDD_5V = 4.5V to 5.5V, TA = -40°C to 85°C, all Typical values at TA = 27°C unless otherwise
noted.
CHARACTERISTIC SYMBOL MIN TYP MAX UNIT CONDITIONS
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3.2 SMBus Electrical Specifications (client mode)
Table 3.3 SMBus Electrical Specifications
VDD= 3V to 3.6V, TA = -40°C to 85°C Typical values are at TA = 27°C unless otherwise noted.
CHARACTERISTIC SYMBOL MIN TYP MAX UNITS CONDITIONS
SMBus Interface
Input High Voltage VIH 2.0 V
Input Low Voltage VIL 0.8 V
Output High Voltage VOH VDD
- 0.4 V
Output Low Voltage VOL 0.4 V 4 mA current sink
Input High/Low Current IIH / IIL ±5 uA Powered and unpowered
Input Capacitance CIN 5pF
SMBus Timing
Clock Frequency fSMB 10 400 kHz
Spike Suppression tSP 50 ns
Bus free time Start to
Stop tBUF 1.3 us
Setup Time: Start tSU:STA 0.6 us
Setup Time: Stop tSU:STP 0.6 us
Data Hold Time tHD:DAT 0.6 6 us
Data Setup Time tSU:DAT 0.6 72 us
Clock Low Period tLOW 1.3 us
Clock High Period tHIGH 0.6 us
Clock/Data Fall time tFALL 300 ns Min = 20+0.1CLOAD ns
Clock/Data Rise time tRISE 300 ns Min = 20+0.1CLOAD ns
Capacitive Load CLOAD 400 pF per bus line
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Chapter 4 Communications
4.1 System Management Bus Interface Protocol
The EMC2105 communicates with a host controller, such as an SMSC SIO, through the SMBus. The
SMBus is a two-wire serial communication protocol between a computer host and its peripheral
devices. A detailed timi ng diagram is shown in Figure 4.1. Stretching of the SMCLK signal is supported,
however the EMC2105 will not stretch the clock signal.
The EMC2105 powers up as an SMBus client.
The EMC2105 contains a single SMBus interface. . The EMC2105 client interfaces are SMBus 2.0
compatible and support Send Byte, Read Byte, Receive Byte and the Alert Response Address as valid
protocols. These protocols are used as shown below.
All of the below protocols use the convention in Table 4.1.
4.2 Write Byte
The Write Byte is used to write one byte of data to the registers as shown below Table 4.2:
Figure 4.1 SMBus Timing Diagram
Table 4.1 Protocol Format
DATA SENT
TO DEVICE DAT A SENT TO
THE HOST
# of bits sent # of bits sent
Table 4.2 Wr ite Byte Protocol
START SLAVE
ADDRESS WR ACK REGISTER
ADDRESS ACK REGISTER
DATA ACK STOP
0 -> 1 0101_111 0 0 XXh 0 XXh 0 1 -> 0
SMDATA
SMCLK
TLOW
TRISE
THIGH
TFALL
TBUF
THD:STA
PSS - Start Condition P - Stop Condition
THD:DAT TSU:DAT TSU:STA
THD:STA
P
TSU:STO
S
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4.3 Read Byte
The Read Byte protocol is used to read one byte of data from the registers as shown in Table 4.3.
4.4 Send Byte
The Send Byte protocol is used to set the internal address register pointer to the correct address
location. No data is transferred during the Send Byte protocol as shown in Table 4.4.
4.5 Receive Byte
The Receive Byte protocol is used to read data from a register when the internal register address
pointer is known to be at the right location (e.g. set via Send Byte). This is used for consecutive reads
of the same register as shown in Table 4.5.
4.6 Alert Response Address
The ALERT# output can be used as a processor interrupt or as an SMBus Alert when configured to
operate as an interrupt.
When it detects that the ALERT# pin is asserted, the host will send the Alert Response Address (ARA)
to the general address of 0001_100xb. All devices with active interrupts will respond with their client
address as shown in Table 4.6.
Table 4.3 Read Byte Protocol
START SLAVE
ADDRESS WR ACK Register
Address ACK START Slave
Address RD ACK Register
Data NACK STOP
0 -> 1 0101_111 0 0 XXh 0 0 -> 1 0101_111 1 0 XXh 1 1 -> 0
Table 4.4 Send Byte Protocol
START SLAVE
ADDRESS WR ACK REGISTER
ADDRESS ACK STOP
0 -> 1 0101_111 0 0 XXh 0 1 -> 0
Table 4.5 Receive Byte Protocol
START SLAVE
ADDRESS RD ACK REGISTER DATA NACK STOP
0 -> 1 0101_111 1 0 XXh 1 1 -> 0
Table 4.6 Alert Response Address Protocol
START
ALERT
RESPONSE
ADDRESS RD ACK DEVICE
ADDRESS NACK STOP
0 -> 1 0001_100 1 0 0101_111 1 1 -> 0
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The EMC2105 will respond to the ARA in the following way if the ALERT# pin is asserted.
1. Send Slave Address and verify that full slave address was sent (i.e. the SMBus communication
from the device was not prematurely stopped due to a bus contention event).
2. Set the MASK bit to clear the ALERT# pin.
4.7 SMBus Address
The EMC2105 SMBus Address is fixed at 0101_111xb.
Attempting to communicate with the EMC210 5 SMBus interface with an in valid sl ave address or invalid
protocol will result in no response from the device and will not affect its register contents.
4.8 SMBus Time-out
The EMC2105 includes an SMBus time-out feature. Following a 30ms period of inactivity on the
SMBus, the device will time-out and reset the SMBus interface. The SMBus Timeout defaults to
enabled and can be disabled by setting the DIS_TO bit in the Configuration 2 register.
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Chapter 5 Product Description
The EMC2105 is an SMBus compliant fan controller with up to four (up to 4 external) temperature
channels. It contains a single High Side fan driver capable of sourcing up to 600mA fro m a 5V supply.
The fan driver can be operated using two methods each with two modes. The methods include an
RPM based Fan Speed Control Algorithm and a direct fan drive setting. The modes include manually
programming the desired settings or using the internal programmable temperature look-up table to
select the desired setting based on measured temperature.
The temperature monitors offer 1°C accuracy (for external diodes) with sophisticated features to
reduce errors introduced b y series resistance and beta variation of substrate thermal diode transistors
commonly found in processors (including support for BJT or transistor model for CPU diodes).
The EMC2105 also includes a hardware programmable temperature limit and dedicated system
shutdown output for thermal protection of critical circuitry. Any of the three temperature channels can
be configured to measure a thermistor or voltage channel using a precision reference voltage for
reduced system complexity.
Figure 5.1 shows a system diagram of the EMC2105.
Figure 5.1 System Diagram of EMC2105
EMC2105
DP1*
DN1*
DP2*
DN2*
CPU
Thermal
diode
Thermal
diode
GPU
3.3V
SMCLK
SMDATA
ALERT#
VDD
TACH1 tachometer
FAN_OUT (2) 3.3V
TRIP_SET*
0.8V
1.2k
3.3V
MCU or
system
controller
VDD_5V (2)
5V
* denotes other functions available on this pin
3.3V
SYS_SHDN#
SHDN_SEL
CLK_IN* 32.768kHz clock
DP3 / DN4*
DN3 / DP4*
APD
(optional)
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5.1 Critical/Thermal Shutdown
The EMC2105 provides a hardware Critical/Thermal Shutdown function for systems. Figure 5.2 is a
block diagram of this Critical/Thermal Shutdown function. The Critical/Thermal Shutdown function in
the EMC2105 accepts configuration information from the fixed states of the SHDN_SEL pin as
described in Section 5.1.1.
Each of the software programmed temperature limits can be optionally configured to act as inputs to
the Critical / Ther mal Shutdown independent of the hardware shutdown operation. When confi gured to
operate this way, the SYS_SHDN# pin will be asserted when the temperature meets or exceeds the
limit. The pin will be released when the temperature drops below the limit however the individual status
bits will not be cleared if set (see Section 6.13).
The analog portion of the Critical/Thermal Shutdown function monitors the hardware determined
temperature channel (see Section 5.1.1). This measured temperature is then compared with
TRIP_SET point. This TRIP_SET point is set by the system designer with a single external resistor
divider as described in Section 5.1.2.
The SYS_SHDN# is asserted when the indicated temperature exceeds the temperature threshold
established by the TRIP_SET i nput pin for a nu mber of co nsecutive measurements defined by the fault
queue. If the HW_SHDN output is asserted and the temperature drops below the Thermal / Critical
Shutdown threshold then it will be set to a logic ‘0’ state.
Figure 5.2 EMC2105 Critical/Thermal Shutdown Block Diagram
Voltage
Conversion
SYS_SHDN#
TRIP_SET
External Diode 1
Critical Shutdown Logic
SMBus Traffic
SW_SHDN
C o n fig u r a tio n
Register
VREF
SHDN_SEL
PIN Decode
‘1’
Temperature
Conversion
Register Enabled
Sensor
Register Enabled
Sensor
Register Enabled
Sensor
Register Enabled
Sensor
0
1
Inte rn a l D io d e
Channel
HW_SHDN
Temperature
Conversion
and Limit
Registers
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5.1.1 SHDN_SEL Pin
The EMC2105 has a ‘strappable’ input (SHDN_SEL) allowing for configuration of the hardware
Critical/Thermal Shutdown input channels. This pin has 3 possible states and is monitored and
decoded by the EMC2105 at power-up . The three possible states are 0 (tied to GND), 1 (tied to 3.3V)
or High-Z (open). The state of this pin determines which external diode configuration is used for the
Critical / Thermal shutdown function.
The different configurations of the SHDN_SELpin are described in Table 5.1. SHDN_SEL applies only
to the selected temperature channel.
5.1.2 TRIP_SET / VIN4 Pin
The EMC2105’s TRIP_SET / VIN4 pin is an an alog input to the Critical/The rmal Shutdown block which
sets the Thermal Shutdown temperature. The system designer creates a voltage level at the input
through a simple resistor conn ected to GND as shown in Figure 5.1. The value of this resistor is used
to create an input voltage on the TRIP_SET / VIN4 pin which is translated into a temperature ranging
from 60°C to 122°C or 90°C to 152°C as enumerated in Table 5.2.
When the SHDN_SEL pin is pulled to ‘1’ at power up, then the TRIP_SET / VIN4 pin is configured to
measure VIN4 as its primary function. The circuitry will still calculate the thermal / critical shutdown
threshold based o n the voltage and compare this temperature against the Internal Diode temperature.
This will cause the SYS_SHDN# pin to assert if the measured temperature exceeds this threshold.
The device will also compare the measured voltage against the VIN4 High and Low limi ts. This functi on
is not available if SHDN_SEL is set to ‘0’ or ‘High-Z’ at power up.
APPLICATION NOTE: If the SHDN_SEL pin is pulled to ‘1’ at power up and the TRIP_SET / VIN4 pin is intended
for use as a voltage input then the SYS_SHDN# pin should be ignored.
APPLICATION NOTE: If the SHDN_SEL pin is pulled to ‘1’ at power up and the TRIP_SET / VIN4 pin is intended
to be used to set a threshold level then the VIN4 channel should be masked. Furthermore,
the voltage on the pin must be externally generated based on Equation [1]. Do not use
Table 5.2.
APPLICATION NOTE: When used in its TRIP_SET mode (i.e. the SHDN_SEL pin is not set to a logic ‘1’), current
only flows when th e TRIP_SET / VIN4 pin is being moni tored. At all other times, the internal
reference voltage is removed and the TRIP_SET / VIN4 pin will be pulled down to ground.
Table 5.1 SHDN_SEL Pin Configuration
SHDN_SEL FUNCTION
NAME TEMPERATURE MONITORING FEATURES CRITICAL / THERMAL
SHUTDOWN RANGE
0 Intel Transistor
Mode (substrate
PNP)
The external diode 1 channel is configured with
Beta Compensation enabled and Resistance
Error Correction enabled. This mode is ideal
for monitoring a substrate transistor such as an
Intel CPU thermal diode.
High - 92°C to 154°C
High-Z (open) AMD CPU /
Diode Mode The external diod e 1channe l is con figured with
Beta Compensation disabled and Resistance
Error Correction disabled. This mode is ideal
for monitoring an AMD processor diode or a
2N3904 diode.
Low - 60°C to 122°C
1 Internal The internal diode is linked to the Hardware set
Thermal / Critical shutdown circuitry and the
SYS_SHDN# pin.
Low - 60°C to 122°C
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APPLICATION NOTE: The TRIP_SET / VIN4 pin circuitry is designed to use a 1% resistor externally. Using a 1%
resistor will result in the Thermal / Critical Shutdown temperature being decoded correctly. If
a 5% resistor is used, then the Thermal / Critical Shutdown temperature may be decoded
with as much as ±1°C error.
VTRIP is the TRIP_SET
voltage [1]
TMIN is the minimum
temperature based on the
range
Table 5.2 TRIP_SET Resistor Setting
TTRIP (°C)
LOW RANGE TTRIP (°C)
HIGH RANGE RSET (1%) TTRIP (°C)
LOW RANGE TTRIP (°C)
HIGH RANGE RSET (1%)
60 92 0.0 92 124 1240
61 93 28.7 93 125 1330
62 94 48.7 94 126 1400
63 95 69.8 95 127 1500
64 96 90.9 96 128 1580
65 97 113 97 129 1690
66 98 137 98 130 1820
67 99 158 99 131 1960
68 100 182 100 132 2050
69 101 210 101 133 2210
70 102 237 102 134 2370
71 103 261 103 135 2550
72 104 294 104 136 2740
73 105 324 105 137 2940
74 106 348 106 138 3160
75 107 383 107 139 3480
76 108 412 108 140 3740
77 109 453 109 141 4120
78 110 487 110 142 4530
79 111 523 111 143 4990
80 112 562 112 144 5490
81 113 604 113 145 6040
82 114 649 114 146 6810
VTRIP TTRIP TMIN
–
80
----------------------------------
=
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5.2 Fan Control Modes of Operation
The EMC2105 has four mo des of operation for the fan driver. Each mode of operation uses th e Ramp
Rate control and Spin Up Routine.
1. Direct Setting Mode- in this mode of operation, the user directly controls the fan drive setting.
Updating the Fan Driver Setting Register (see Section 6.18) will instantly update the fan drive.
Ramp Rate control is optional and enabled via the EN_RRC bits.
This is the default mode. The Direct Setting Mode is enabled by clearing the LUT_LOCK bit
in the Look Up Table Configuration Register (see Section 6.29) while the TACH / DRIVE bit
is set to ‘0’.
Whenever the Direct Setting Mode is enabled the current drive will be changed to what was
last written into the Fan Driver Setting Register.
2. Fan Speed Control Mode (FSC) - in this mode of operation, the user determines a target
tachometer count and the drive setting is automatically updated to achieve this target speed. The
algorithm uses the Spin Up Routine and has user definable ramp rate controls.
This mode is enabled by clearing the LUT_LOCK bit in the Look Up Table (LUT)
Configuration Register and setting the EN_ALGO bit in the Fan Configuration Register.
3. Using the Look Up Table with Fan Drive Settings (Direct Setting w/ LUT Mode) - In this mode of
operation, the user programs the Look Up Table with fan drive settings and corresponding
temperature thresholds. The fan drive is set based on the measured temperatures and the
corresponding drive settings. Ramp Rate control is optional and enabled via the EN_RRC bits.
This mode is enabled by programming the Look Up Table then setting the LUT_LOCK bit
while the TACH / DRIVE bit is set to ‘1’.
The TACH / DRIVE bit in the Look Up Table Configuration Register MUST be set to ‘1’ or
the fan drive settings will be incorrectly set. Setting this bi t to ‘1’ ensures the settings will be
PWM settings.
4. Using the Lo ok Up Table with RPM Target Settings (FSC w/ LUT Mode) - In this mode of op eration,
the user programs the Look Up Table with TACH Target values and corresponding temperature
thresholds. The TACH Target will be set based on the measured temperatures and the
corresponding target settings. The fan drive settings will be dete rmined automatically based on the
RPM based Fan Speed Control Algorithm.
This mode is enabled by programming the Look Up Table then setting the LUT_LOCK bit
while the TACH / DRIVE bit is set to ‘0’.
83 115 698 115 147 7870
84 116 750 116 148 9090
85 117 787 117 149 10700
86 118 845 118 150 12700
87 119 909 119 151 15800
88 120 953 120 152 20500
89 121 1020 121 153 29400
90 122 1100 122 154 49900
91 123 1150 60 92 Open
Table 5.2 TRIP_SET Resistor Setting (continued)
TTRIP (°C)
LOW RANGE TTRIP (°C)
HIGH RANGE RSET (1%) TTRIP (°C)
LOW RANGE TTRIP (°C)
HIGH RANGE RSET (1%)
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The TACH / DRIVE bit in the Look Up Table Configuration Register MUST be set to ‘0’ or
the TACH Target values will be incorrectly set. Se tting this bit to ‘0’ ensures that the se ttings
will be RPM settings (Tachometer counts).
5.3 High Side Fan Driver
The EMC2105’s contains a 5V, 600mA, linear high side fan driver to directly drive a 5V fan. By fully
integrating the li near fan driver, the typical requirement for the discrete pass device and other external
linearization circuitry is complete ly eliminated. The linear fan driver is driven by an 8-bit DAC providing
better than 20mV resolution between steps.
5.3.1 Over Current Limit
The High Side Fan Drive r contains circuitry to a llow for significant over current levels to accommo date
transient conditi ons on the FAN pins. The over current limit is dependent upon the output voltage with
the limit dropping as the voltage nears 0V.
If the fan driver current detects a short-circuit condition for longer than 2 seconds, then the I_SHORT
status bit is set and an interrupt generated. Additionally, the High Side Fan Driver will be disabled for
Table 5.3 Fan Controls Active for Operating Mode
DIRECT SETTING
MODE FSC MODE DIRECT SETTING W/ LUT
MODE FSC W/ LUT MODE
Fan Driver Setting
(read / write) Fan Driver Setting (read
only) Fan Driver Setting (read
only) Fan Driver Setting (read
only)
EDGES[1:0] EDGES[1:0]
(Fan Configuration) EDGES[1:0] EDGES[1:0]
- RANGE[1:0]
(Fan Configuration) - RANGE[1:0]
(Fan Configuration)
UPDATE[2:0]
(Fan Configuration) UPDATE[2:0]
(Fan Configuration) UPDATE[2:0]
(Fan Configuration) UPDATE[2:0]
(Fan Configuration)
LEVEL
(Spin Up
Configuration)
LEVEL
(Spin Up Configuration) LEVEL
(Spin Up Configuration) LEVEL
(Spin Up Configuration)
SPINUP_TIME[1:0]
(Spin Up
Configuration)
SPINUP_TIME[1:0]
(Spin Up Configuration) SPINUP_TIME[1:0]
(Spin Up Configuration) SPINUP_TIME[1:0]
(Spin Up Configuration)
Fan Step Fan Step Fan Step Fan Step
- Fan Minimum Drive Fan Minimum Drive
Valid TACH Count Valid TACH Count Valid TACH Count Valid TACH Count
- TACH Target (read / write) - TACH Target (read
only)
TACH Reading TACH Reading TACH Reading TACH Reading
- - Look Up Table Drive /
Temperature Settings (read
only)
Look up Table Drive /
Temperature Settings
(read only)
- DRIVE_FAIL_CNT[1:0] and
Drive Band Fail Registers - DRIVE_FAIL_CNT[1:0]
and Drive Band Fail
Registers
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8 seconds. After this 8 second time has elapsed, it will be allowed to restart invoking the Spin Up
Routine before returning to its previous drive setting.
APPLICATION NOTE: If the FSC Algorithm is active, then it will generate errant SPIN_FAIL interrupts during the 8
second time that the fan driver is held off.
5.4 Fan Control Look-Up Table
The EMC2105 uses a look-up table to apply a user-programmable fan control profile based on
measured temperature to the fan driver. In this look-up table, each temperature channel is allowed to
control the fan drive output independently (or jointly) by programming up to eight pairs of temperature
and drive setting entries.
The user programs the look-up table based on the desired operation. If the RPM based Fan Speed
Control Algorithm is to be used (see Section 5.5), then th e user must program an RPM target for each
temperature setting of interest. Altern ately, if the RPM based Fan Speed Control Algorithm is not to be
used, then the user must program a drive setting for each temperature setting of interest.
If the measured temperature on the External Diode channel meets or exceeds any of the temperature
thresholds for any of the temperature columns (see Appendix B), the fan output will be automatically
set to the desired setting corresponding to the exceeded temperature. In cases where multiple
temperature channel thresholds are exceeded, the highest fan drive setting will take precedence.
When the measured temperat ure drops to a point below a lower threshold minus the hysteresis value,
the fan output will be set to the corresponding lower set point.
Figure 5.3 shows an example of this operation using temperature - drive setting pairs for a single
channel.
See Appendix B for examples of the Look Up Table operation.
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5.4.1 Programming the Look Up Table
When the Look Up Table is used, it must be loaded and configured correctly based on the system
requirements. The following steps outline the procedure.
1. Determine whether the Look Up Table will drive a fan setting or a tachometer target value and set
the TACH / DRIVE bit in the Fan LUT Configuration Register.
2. Determine which measurement channels (up to four) are to be used with the Look Up Table and
set the TEMP3_CFG and TEMP4_CFG bits accordingly in the Fan LUT Configuration Register.
3. For each step to be used in the LUT, set the Fan Se tting (either fan setting or TACH Target as set
by the TACH / DRIVE bit). If a setting is not used, then set it to FFh (if a fan setting) or 00h (if a
TACH Target). Load the lowest settings first in ascending order (i.e. Fan Setting 1 is the lowest
setting greater than “off”. Fan Setting 2 is the next highest setting, etc.).
4. For each step to be used in the LUT, set each of the measurement channel thresholds. These
values must be set in the same data format that the data is presented. If DTS is to be used, then
Figure 5.3 Fan Control Look-Up Table Example
Time
Fan
Setting
Temp
S2
S3
S4
T4
T5
T6
Averaged
Temperature
T4 - Hyst
T5 - Hyst
T6 - Hyst
S1
T3
T3 - Hyst
T2
T2 - Hyst
S6
T1
S5
Measurement taken
Fan
Setting
T7
T7 - Hyst
T8
T8 - Hyst
S7
S8
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the format should be in temperature with a maximum threshold of 100°C (64h). If a measurement
channel is not used, then set the threshold at FFh.
5. Set the Hysteresis value to be smaller than the smallest threshold step.
6. Configure the RPM based Fan Speed Control Algorithm if it is to be used.
7. Set the LUT_LOCK bit to enable the Look Up Table and begin fan control.
5.4.2 DTS Support
The EMC2105 supports DTS (Intel’s Digital Temperature Sensor) data in the Fan Control Look Up
Table. Intel’s DTS data is a positive number that represents the processor ’s relative temperature below
a fixed value called TCONTROL which is generally equal to 100°C for Intel Mobile processors. For
example, a DTS value of 10°C means that the ac tual processor temperature is 10°C below TCONTROL
or equal to 90°C.
Either or both of the Pushed Temperature Registers can be written w ith DTS data and used to control
the fan driver. When DTS data is entered, then the USE_DTS_Fx bit must be set in the Fan LUT
Configuration register. Once this bit is set, the DTS data entered is automatically subtracted from a
value of 100°C. This delta value is then used in the Look Up Table as standard temperature data. See
Appendix B for examples on using DTS data in the Look Up Table.
APPLICATION NOTE: The device is designed with the assumption that TCONTROL is 100°C. As such, all DTS
related conversions are done based on this value including Look Up Table comparisons. If
TCONTROL is adjusted (i.e. TCONTROL is shifted to 105°C), then all of the Look Up Table
thresholds should be adjusted by a value equal to TCONTROL - 100°C.
5.5 RPM based Fan Speed Control Algorithm (FSC)
The EMC2105 include s an RPM based Fan Speed Control Algorithm. T he algorithm can be controlled
manually (by setting the target fan speed) or via a look up table.
This fan control algorithm uses Proportional, Integral, and Derivative terms to automatically approach
and maintain the system’s desired fan speed to an accuracy directly proportional to the accuracy of
the clock source. Figure 5.4 shows a simple flow diagram of the RPM based Fan Speed Control
Algorithm operation.
The desired tachometer count is set by the user inputting the desired number of 32.768KHz cycles
that occur per fan revolution. This is done by either manually setting the TACH Target Register or by
programming the Temperature Look-Up Table. The user may change the target count at any time. The
user may also set the target count to FFh in order to disable the fan driver for lower current ope ration.
For example, if a desired RPM rate for a 2-pole fan is 3000 RPMs, then the user would input the
hexidecimal equivalent of 1296 (51h in the TACH Targe t Register). Thi s number represen ts the number
of 32.768KHz cycles that would occur during the time it takes the fan to complete a single revolution
when it is spinning at 3000RPMs.
The EMC2105’s RPM based Fan Speed Control Algorithm has programmable configuration settings
for parameters such as ramp-rate control and spin up conditions. The fan driver automatically detects
and attempts to alleviate a stalled/stuck fan condition while also asserting the ALERT# pin. The
EMC2105 works with fans that operate up to 16,000 RPMs an d provide a valid tachometer signal. The
fan controller will function either with an externally supplied 32.768KHz clock source or with it’s own
internal 32kHz oscillator depending on the required accuracy.
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Figure 5.4 RPM based Fan Speed Control Algorithm
Set TACH Target
Count
TACH
Reading =
TACH
Target?
Spin Up
Required
?
Perform Spin Up
Routine
M a in t a in F a n D riv e
TACH
Reading <
TACH
Target?
Reduce F an D rive Increase Fan Drive
Measure Fan S peed
Yes
No
Yes No
Yes
No
Ra mp Rate C o n t ro l
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5.5.1 Programming the RPM Based Fan Speed Control Algorithm
The RPM based Fan Speed Control Algorithm is disabled upon device power up. The following
registers control the algorithm. The EMC2105 fan control registers are pre-loaded with defaults that
will work for a wide variety of fans so only the TACH Target Register is required to set a fan speed.
The other fan control registers can be used to fine-tune the algorithm behavior based on application
requirements.
Note that steps 1 - 6 are optional and need only be performed if the default settings do not provide
the desired fan response.
1. Set the Spin Up Configuration Register to the Spin Up Level and Spin Time desired.
2. Set the Fan Step Register to the desired step size.
3. Set the Fan Minimum Drive Register to the minimum drive value that will maintain fan operation.
4. Set the Update Time, and Edges options in the Fan Configuration Register.
5. Set the Valid TACH Count Register to the highest tach count that indicates the fan is spinning.
6. Set the TACH Target Register to the desired tachometer count.
7. Enable the RPM based Fan Speed Control Algorithm by setting the EN_ALGO bit.
5.6 Tachometer Measurement
The tachometer measurement circuitry is used in conjunction with the RPM based Fan Speed Control
Algorithm to update the fan driver output. Additionally, it can be used in Direct Setting mode as a
diagnostic for host based fan control.
This method monitors the TACHx signal in real time. It constantly updates the tachometer
measurement by reporting the numb er of clocks between a user programmed number of e dges on the
TACHx signal (see Table 6.26).
The tachometer measurement provides fast response times for the RPM based Fan Speed Control
Algorithm and the data is presented as a count value that represents the fan RPM period. When this
method is used, all fan target values must be input as a count value for proper operation.
APPLICATION NOTE: The tachometer measurement method works independently of the drive settings. If the
device is put into Direct Setting and the fan drive is set at a level that is lower than the fan
can operate (including zero drive), then the tachometer measurement may signal a Stalled
Fan condition and assert an interrupt.
5.6.1 Stalled Fan
A Stalled fan is detected if the tach counter exceeds the user-programmable Valid TACH Count setti ng
then it will flag the fan as stalled and trigger an interrupt.
If the RPM based Fan Speed Control Algorithm is enabled, the algorithm will automatically attempt to
restart the fan until it detects a valid tachometer level or is disabled.
The FAN_STALL Status bit indicates that a stalled fan was detected. This bit is checked conditionally
depending on the mode of operation.
Whenever the Direct Setting Mode or Direct Setting with LUT Mode is enabled or whenever the
Spin Up Routine is enabled, the FAN_STALL interrupt will be masked for the duration of the
programmed Spin Up Time (see Table 6.36) to al low the fan an opportun ity to reach a valid speed
without generating unnecessary interrupts.
In Direct Setting Mode or Direct Setting w/ LUT Mode, and the tachometer measurement is using
the Tach Perio d Measurement method, then whene ver the TAC H Reading Register value exceeds
the Valid TACH Count Register setting, the FAN_STALL status bit will be set.
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When using the RPM based Fan Speed Control Algorithm (either FSC Mode or LUT with FSC
Mode), the stalled fan condition is checked whenever the Update Time is met and the fan drive
setting is updated. It is not a continuous check.
5.6.2 32kHz Clock Source
The EMC2105 allows the user to choose between supplying an external 32.768kHz clock or use of
the internal 32kHz oscillator to measure the tachometer signal. This clock source is used by the RPM
based Fan Speed Control Algorithm to calculate the current fan speed. This fan controller accuracy is
directly proportional to the accuracy of the clock source.
The external clock is provided on the CLK_IN. In order for the external clock to be used, the EXT_CLK
bit must be set in the Configuration Register.
5.6.3 Aging Fan or Invalid Drive Detection
This is useful to detect aging fan conditions (where the fan’s natural maximum speed degrades over
time) or incorrect fa n speed settings.The EMC2105 co ntains circuitry that detects that the programmed
fan speed can be reached by the fan. If the target fan speed cannot be reached within a user defined
band of tach counts at maximum drive then the DRIVE_FAIL status bits are set and the ALERT# pin
is asserted.
5.7 Spin Up Routine
The EMC2105 also contains programmable circuitry to control the spin up behavior of the fan driver
to ensure proper fan operation.
The Spin Up Routine is initiated in Direct Setting mode (with or without the Look Up Table - when
enabled) when the setting value changes from 00h to anything else.
When the Fan Speed Control Alg orithm is enabled, the Spin Up Routine is initiated under the following
conditions when the Tach Period Measurement method of tach measurement is used:
1. The TACH Target Register value changes from a value of FFh to a value that is less than the Valid
TACH Count (see Section 6.25).
2. The RPM based Fan Speed Control Algorithm’s measured TACH Reading Register value i s greater
than the Valid TACH Count setting.
When the Spin Up Routine is operating, the fan driver is set to full scale (optional) for one quarter of
the total user defined spin up time. Fo r the remaining sp in up time, the fan driver ou tput is set a a user
defined level (30% through 65% drive).
After the Spin Up Routine has finished, the EMC2105 measures the TACHx signal. If the measured
TACH Reading Register value is higher than the Valid TACH Count Register setting, the FAN_SPIN
status bit is set and the Spin Up Routine will automatically attempt to restart the fan.
Figure 5.5 shows an example of the Spin Up Routine i n response to a programmed fan speed change
based on the first condition above.
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5.8 Ramp Rate Control
The Fan Driver can be configured with automatic ramp rate control. Ramp rate control is accomplish ed
by adjusting the drive output settings based on the Maximum Fan Step Register settings and the
Update Time settings.
If the RPM based Fan Speed Control Algorithm is used, then this ramp rate control is automatically
used. The user programs a maximum step size for the fan drive setting and an update time. The
update time varies from 100ms to 1.6s while the fan drive maximum step can vary from 1 count to 31
counts.
When a new fan drive setti ng is entered, the delta from the next fan drive setting and th e previous fan
drive setting is determined. If this delta is greater than the Max Step settings, then the fan drive setti ng
is incrementally adjusted every 100ms to 1.6s as determined by the Update Time until the target fan
drive setting is reached. See Figure 5.6.
Figure 5.5 Spin Up Routine
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5.9 Watchdog Timer
The EMC2105 contains an internal Watchdog Timer. Once the device has powered up the watchdog
timer monitors the SMBus traffic for signs of activity. The Watchdog Timer starts when the internal
supply has reached its operating point. The Watchdog Timer only starts immediately after power-up
and once it has been triggered or deactivated will not restart.
If four (4) seconds elapse without the system host programming the device, then the watchdog will be
triggered and the following will occur:
1. The WATCH status bit will be set.
2. The fan driver will be set to full scale drive. It will remain at full scale drive until one of the three
conditions listed below are met.
If the Watchdog Timer is triggered, the following three operations will disable the timer and return the
device to normal operation. Alternately, if the Watchdog Timer has not yet been triggered performing
any one of the following will disable it.
1. Writing the Fan Setting Register will disable the Watchdog Timer.
2. Enab ling the RPM based Fan Speed Control Algorithm by setting the EN_ALGO bit will disable the
Watchdog Timer. The fan driver wil l be set based on the RPM ba sed Fan Spee d Control Algorithm.
3. Setting the LUT_LOCK bitwill disable the Watchdog Timer. The fan driver will be set based on the
Look Up Table settings.
Writing any other configuration registers will not disable the Watchdog Timer.
APPLICATION NOTE: Disabling the Watchdog will not automa tically set the fan driv e. This must be done manually
(or via the Look Up Table).
Figure 5.6 Ramp Rate Control
Previous
Setting
Next Desired
Setting
Max
Step
Max
Step
Update
Time Update
Time
Setting Changed
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5.10 Internal Thermal Shutdown (TSD)
The EMC2105 contains an internal the rmal shutdown circuit that monitors the internal die temperature.
If the die temperature exceeds the Thermal Shutdown Threshold (see Table 3.2), then the following
will occur:
1. The High Side Fan Driver is disabled. It will remain disabled until the internal temperature drops
below the threshold temperature minus 50°C.
2. The TSD Status bit will be set and the SYS_SHDN# pin asserted.
3. The SYS_SHDN# pin is asserted.
APPLICATION NOTE: When the fan driver is disabled via a thermal shutdown event, the drive settings will not be
altered. Thus, when the temperature drops below the thre shold minus the hysteresis, the fan
will return to its previous drive setting.
5.11 Fault Queue
The EMC2105 contains a programmable fault queue on all fault conditions except a FAN_SHORT or
TSD condition (including all temperature high, low, and tcrit limits as well as the hardware set thermal
limit). The fault queue defines how many consecutive out-of-limit conditions must be reported before
the corresponding status bit is set (and the ALERT# pin asserted).
APPLICATION NOTE: With the exception of the Tcrit limit, the fault queue is not applied to the internal diode
measurement.
5.12 Temperature Monitoring
The EMC2105 can monitor the temperature of up to four (4) externally connected diodes as well as
the internal or ambie nt temperature. Each channel is configured with the following features enabled or
disabled based on user settings and system requirements.
APPLICATION NOTE: When measuring an Intel 45nm CPU, the reported temperature will have an error of
approximately 1.5°C at 100°C. This error i s related to a non-perfect idea lity factor of th e CPU
diode and is proportional to the diode temperature.
5.12.1 Dynamic Averaging
The EMC2105 supports dynamic averaging. When enabled, this feature changes the conversion time
for all channels based on the se lected conversion rate. This essentially increases the averaging factor
as shown in Table 5.4. The benefits of Dynamic Averaging are improved noise rejection due to the
longer integration time as well as less random variation on the temperature measurement.
Table 5.4 Dynamic Averaging Behavior
CONVERSION RATE
AVERAGING FACTOR (RELATIVE TO 11-BIT CONVERSI0N)
DYNAMIC AVERAGING
ENABLED DYNAMIC AVERAGING
DISABLED
1 / sec 8x 1x
2 / sec 4x 1x
4 / sec 2x 1x
8 / sec 1x 1x
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5.12.2 Resistance Error Correction
The EMC2105 includes active Resistance Error Correction to remove the effect of up to 100 ohms of
series resistance. Without this automatic feature, voltage developed across the parasitic resistance in
the remote diode path causes the temperature to read higher than the true temperature is. The error
induced by parasitic resistance is approximately +0.7°C per ohm. Sources of parasitic resistance
include bulk resistance in the remote temperature transistor junctions, series resistance in the CPU,
and resistance in the printed circu it board traces and package lea ds. Resistance error correction in the
EMC2105 eliminates the need to characterize and compensate for parasitic resistance in the remote
diode path.
5.12.3 Beta Compensation
The forward current gain, or beta, of a transistor is not constant as emitter currents change. As well,
it is not constant over changes in temperature. The variation in beta causes an error in temperature
reading that is proportional to absolute temperature. This correction is done by implementing the BJT
or transistor model for temperature measurement.
For discrete transistors configured with the collector and base shorted together, the beta is generally
sufficiently high such that the percent change in beta variation is very small. For example, a 10%
variation in beta for two forced emitter currents with a tran sistor whose ideal beta is 50 would contribute
approximately 0.25°C error at 100°C. However for substrate transistors where the base-emitte r juncti on
is used for temperature measurement and the collector is tied to the substrate, the proportional beta
variation will cause large error. For example, a 10% variation in beta for two forced emitter currents
with a transistor whose ideal beta is 0.5 would contribute approximately 8.25°C error at 100°C.
The Beta Compensation circuitry in the EMC2105 corrects for this beta variatio n to eliminate any error
which would normally be induced. It automatically detects the appropriate beta setting to use.
5.12.4 Digital Averaging
The External Diode 1 channel support a 4x digital averaging filter. Every cycle, this filter updates the
temperature data based an a running average of the last 4 measured temperature values. The digital
averaging reduces temperature flickering and increases temperature measurement stability.
The digital averaging can be disabled by setting the DIS_AVG bit in the Configuration 2 Register (see
Section 6.10).
5.13 Thermistor Support
The External Diode 1, External Diode 2, and External Diode 3 channels can be configured to monitor
a thermistor. When this function is enabled, the data on the VIN1, VIN2, or VIN3 channels can be
configured to measure a simple voltage input or a ground-connected thermistor circuit (see Appendix
A for more information).
The External Diode 1 channel can only be configured as a voltage input if the SHDN_SEL pin is set
to a logic ‘1’.
5.14 Diode Connections
The diode connection for the External Diode 1 channel is determined at power-up based on the
SHDN_SEL pin (see Section 5.1.1). This channel can support a diode-connected transistor (such as
a 2N3904) or a substrate transistor (such as those found in an CPU or GPU) as shown in Figure 5.7.
The External Diode 3 channel sup ports any diode connection shown or it can be configured to operate
in anti-parallel diode (APD) mode. When configured in APD mode, a fourth temperature channel is
available that shares the DP3 and DN3 pins. When in this mode, both the external diode 3 channel
and external diode 4 channel thermal diodes must be connected as a diode.
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5.14.1 Diode Faults
The EMC2105 actively detects an open and short condition on each measurement channel. When a
diode fault is detected, the temperature data MSByte is forced to a value of 80h and the FAULT bit is
set in the Status Register. When the External Diode 3 channel is configured to operate in APD mode,
the circuitry will detect independent open fault conditions, however a short condition will be shared
between the External Diode 3 and External Diode 4 channels.
5.15 GPIOs
The EMC2105 contains a single GPIO pin (multiplexed with other functions). The GPIO pin can be
configured as an input or an output and as a push-pull or open-drain output. Additionally, the GPIO
pin, when configured as an input, can be enabled to trigger an interrupt when it changes states.
5.16 Interrupts
If a change of state occurs (such as a temperature out-of-limit condition or a GPIO changing states)
then the following will occur:
1. The appropriate status bits will be set in the Status Register and in the High, Low, and Fault Status
Registers.
2. The ALERT# will be asserted if the specific channel interrupt is enabled (see Section 6.15).
The ALERT# pin is cleared by setting the MASK bit, disabling the specific interrupt channel enable, or
reading the status registers. If the error conditions persist, then the status bits will remain set. Unless
the Interrupt Status Enable bits are cleared or the MASK bit is set, the ALERT# pin will likewise be set.
Figure 5.7 Diode Connections
Local Ground
to
DP
Typical remote
substrate transistor
i.e. CPU substrate PNP
Typical remote
discrete PNP transistor
i.e. 2N3906
Typical remote
discrete NPN transistor
i.e. 2N3904
to
DN
to
DP
to
DN
to
DP
to
DN
Anti-parallel diodes using
discrete NPN transistors
Diode 1Diode 2
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Chapter 6 Register Set
6.1 Register Map
The following registers are accessible through the SMBus Interface. All register bits marked as ‘-’ will
always read ‘0’. A write to these bits will have no effect.
Tab le 6.1 EMC2105 Register Set
ADDR R/W REGISTER
NAME FUNCTION DEFAULT
VALUE LOCK PAGE
Temperature Registers
00h R Internal Temp
Reading High
Byte Stores the integer data of the Internal
Diode 00h No Page 45
01h R Internal Temp
Reading Low Byte Stores the fracti onal da ta of the Internal
Diode 00h No Page 45
02h R External Diode 1
Temp Reading
High Byte Stores the integer data of External
Diode 1 and VIN1 channel 00h No Page 45
03h R External Diode 1
Temp Reading
Low Byte Stores the fractional data of External
Diode 1 00h No Page 45
04h R External Diode 2
Temp Reading
High Byte Stores the integer data of External
Diode 2 and VIN2 channel 00h No Page 45
05h R External Diode 2
Temp Reading
Low Byte Stores the fractional data of External
Diode 2 00h No Page 45
06h R External Diode 3
Temp Reading
High Byte Stores the integer data of External
Diode 3 and VIN3 channel 00h No Page 45
07h R External Diode 3
Temp Reading
Low Byte Stores the fractional data of External
Diode 3 00h No Page 45
08h R External Diode 4
Temp Reading
High Byte Stores the integer data of External
Diode 4 00h No Page 45
09h R External Diode 4
Temp Reading
Low Byte Stores the fractional data of External
Diode 4 00h No Page 45
0Ah R Critical/Thermal
Shutdown
Temperature
Stores the calculated Critical/Thermal
Shutdown temperature high limit
derived from the voltage on TRIP_SET
/ VIN4
7Fh
(+127°C) No Page 47
0Ch R/W Pushed
Temperature 1 Stores the integer data for Pushed
Temperature 1 to drive LUT 00h No Page 47
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0Dh R/W Pushed
Temperature 2 Stores the integer data for Pushed
Temperature 2 to drive LUT 00h No Page 47
10h R Trip Set Voltage Stores the raw measured TRIP_SET
voltage or the VIN4 analog vo ltage input FFh No Page 48
Diode Configuration
14h R/W External Diode 1
Beta
Configuration Configures the beta compensation
settings for External Diode 1 10h SWL Page 48
15h R/W External Diode 2
Beta
Configuration Configures the beta compensation
settings for External Diode 2 10h SWL Page 48
16h R/W External Diode 3
Beta
Configuration Configures the beta compensation
settings for External Diode 3 10h SWL Page 48
17h R/W External Diode
REC
Configuration
Configures the Resistance Error
Correction functionality for all external
diodes 07h SWL Page 49
19h R/W External Diode 1
Tcr it Limit Stores the Critical temperature limit for
the External Diode 1 64h
(100°C) Write
Lock Page 50
1Ah R/W External Diode 2
Tcr it Limit Stores the Critical temperature limit for
the External Diode 2 64h
(100°C) Write
Lock Page 50
1Bh R/W External Diode 3
Tcr it Limit Stores the Critical temperature limit for
the External Diode 3 64h
(100°C) Write
Lock Page 50
1Ch R/W External Diode 4
Tcr it Limit Stores the Critical temperature limit for
the External Diode 4 64h
(100°C) Write
Lock Page 50
1Dh R/W Internal Diode
Tcr it Limit Stores the Critical temperature limit for
the Internal Diode 64h
(100°C) Write
Lock Page 50
Configuration and control
1Fh R-C Tcrit Limit Status Stores the status bits for all temperature
channel Tcrit limits 00h No Page 53
20h R/W Configuration Configures the Thermal / Critical
Shutdown masking options and
software lock 00h SWL Page 50
21h R/W Configuration 2 Controls the conversion rate for
monitoring of all channels 0Eh SWL Page 51
22h R/W Configuration 3 Controls the VIN1 - 3 channels 00h SWL Page 53
23h R Interrupt Status Stores the status bits for temperature
channels 00h No Page 53
24h R-C High Limit Status Stores the status bits for all temperature
channel high limits 00h No Page 54
25h R-C Low Limit Status S tores the status bits for all temperature
channel low limits 00h No Page 54
Table 6.1 EMC2105 Register Set (continued)
ADDR R/W REGISTER
NAME FUNCTION DEFAULT
VALUE LOCK PAGE
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26h R-C Diode Fault Stores the status bits for all temperature
channel diode faults 00h No Page 54
27h R-C Fan Status Stores the status bits for the RPM
based Fan Speed Control Algorithm 00h No Page 55
28h R/W Interrupt Enable
Register Controls the masking of interrupts on all
temperature channels 00h No Page 55
29h R/W Fan Interrupt
Enable Register Controls the masking of interrupts on all
fan related channels 00h No Page 56
Temperature Limit Registers
30h R/W External Diode 1
Temp High Limit High limit for External Diode 1 or VIN1 55h
(+85°C) SWL Page 57
31h R/W External Diode 2
Temp High Limit High limit for External Diode 2 or VIN2 55h
(+85°C) SWL Page 57
32h R/W External Diode 3
Temp High Limit High limit for External Diode 3 or VIN3 55h
(+85°C) SWL Page 57
33h R/W External Diode 4
Temp High Limit High Limit for External Diode 4 55h
(85°C) SWL Page 57
34h R/W Internal Diode
High Limit High Limit for Internal Diode 55h
(85°C) SWL Page 57
35h R/W Voltage 4 High
Limit High Limit for the Voltage 4 channel FFh
(0.8V) SWL Page 57
38h R/W External Diode 1
Temp Low Limit Low Limit for External Diode 1 or VIN1 00h
(0°C) SWL Page 57
39h R/W External Diode 2
Temp Low Limit Low Limit for External Diode 2 or VIN2 00h
(0°C) SWL Page 57
3Ah R/W External Diode 3
Temp Low Limit Low Limit for External Diode 3 or VIN3 00h
(0°C) SWL Page 57
3Bh R/W External Diode 4
Temp Low Limit Low Limit for External Diode 4 00h
(0°C) SWL Page 57
3Ch R/W Internal Diode
Low Limit Low Limit for Internal Diode 00h
(0°C) SWL Page 57
3Dh R/W Voltage 4 Low
Limit Low limit for Voltage 4 Channel 00h
(0V) SWL Page 57
Fan Control Registers
40h R/W Fan Setting
Always displays the most recent fan
driver input setting for the Fan. If the
RPM based Fan Speed Control
Algorithm is disabled, allows direct user
control of the fan driver.
00h No Page 58
42h R/W Fan
Configuration 1 Sets configuration values for the RPM
based Fan Speed Co ntrol Algorithm for
the Fan driver 2Bh No Page 58
Table 6.1 EMC2105 Register Set (continued)
ADDR R/W REGISTER
NAME FUNCTION DEFAULT
VALUE LOCK PAGE
RPM-Based High Side Fan Controller with Hardware Thermal Sh utdown
Datasheet
SMSC EMC2105 41 Revision 1.78 (04-21-09)
DATASHEET
43h R/W Fan
Configuration 2 Sets additional configu ration values for
the Fan driver 38h SWL Page 60
45h R/W Gain Holds the gain terms used by the RPM
based Fan Speed Co ntrol Algorithm for
the Fan driver 2Ah SWL Page 61
46h R/W Fan Spin Up
Configuration Sets the configuration values for Spin
Up Routine of the Fan driver 19h SWL Page 62
47h R/W Fan Step Sets the maximum change per update
for the Fan driver 10h SWL Page 63
48h R/W Fan Minimum
Drive Sets the minimum drive value for the
Fan driver 66h
(40%) SWL Page 64
49h R/W Fan Valid TACH
Count Holds the minimu m tachometer reading
that indicates the fan is spinning
properly F5h SWL Page 64
4Ah R/W Fan Drive Fail
Band Low Byte Store s the number of Tach coun ts used
to determine how the actual fan speed
must match the target fan speed at fu ll
scale drive
00h SWL Page 65
4Bh R/W Fan Drive Fail
Band High Byte 00h SWL
4Ch R/W TACH Target Low
Byte Holds the target tachometer reading low
byte the Fan F8h No Page 65
4Dh R/W T ACH Target High
Byte Holds the target tachometer reading
high byte for the Fan FFh No Page 65
4Eh R TACHReading
High Byte Holds the tachometer reading high byte
for the Fan FFh No Page 66
4Fh R TACHReading
Low Byte Holds the tachometer reading low byte
for the Fan F8h No Page 66
Look Up Table (LUT)
50h R/W LUT Configuration Stores and controls the configuration for
LUT 00h No Page 66
51h R/W LUT Drive 1 Stores the lowest programmed drive
setting for the LUT FBh LUT
Lock Page 68
52h R/W LUT Temp 1
Setting 1 Stores the threshold level for the
External Diode 1 (or VIN1) channel that
is associated with the Drive 1 value 7Fh
(127°C) LUT
Lock Page 68
53h R/W LUT Temp 2
Setting 1 Stores the threshold level for the
External Diode 2 (or VIN2) channel that
is associated with the Drive 1 value 7Fh
(127°C) LUT
Lock Page 68
54h R/W LUT Temp 3
Setting 1
Stores the threshold level for the
External Diode 3 channel (or VIN3 or
TRIP_SET voltage or Pushed Temp 1
temp) that is associated with the Drive 1
value
7Fh
(127°C) LUT
Lock Page 68
Table 6.1 EMC2105 Register Set (continued)
ADDR R/W REGISTER
NAME FUNCTION DEFAULT
VALUE LOCK PAGE
RPM-Based High Side Fan Controller with Hardware Thermal Shutdown
Datasheet
Revision 1.78 (04-21-09) 42 SMSC EMC2105
DATASHEET
55h R/W LUT Temp 4
Setting 1
Stores the threshold level for the
Internal Diode channel (or Pushed
Temp 2 temp) that is associated with the
Drive 1 value
7Fh
(127°C) LUT
Lock Page 68
56h R/W LUT Drive 2 Stores the second programmed drive
setting for the LUT E6h LUT
Lock Page 68
57h R/W LUT Temp 1
Setting 2 Stores the threshold level for the
External Diode 1 (or VIN1)chan nel that
is associated with the Drive 2 value 7Fh
(127°C) LUT
Lock Page 68
58h R/W LUT Temp 2
Setting 2 Stores the threshold level for the
External Diode 2 (or VIN2) channel that
is associated with the Drive 2 value 7Fh
(127°C) LUT
Lock Page 68
59h R/W LUT Temp 3
Setting 2
Stores the threshold level for the
External Diode 3 channel (or VIN3 or
TRIP_SET voltage or Pushed Temp 1
temp) that is associated with the Drive 2
value
7Fh
(127°C) LUT
Lock Page 68
5Ah R/W LUT Temp 4
Setting 2
Stores the threshold level for the
Internal Diode channel (or Pushed
Temp 2 temp) that is associated with the
Drive 2 value
7Fh
(127°C) LUT
Lock Page 68
5Bh R/W LUT Drive 3 Stores the third programmed drive
setting for the LUT D1h LUT
Lock Page 68
5Ch R/W LUT Temp 1
Setting 3 Stores the threshold level for the
External Diode 1 (or VIN1) channel that
is associated with the Drive 3 value 7Fh
(127°C) LUT
Lock Page 68
5Dh R/W LUT Temp 2
Setting 3 Stores the threshold level for the
External Diode 2 (or VIN2) channel that
is associated with the Drive 3 value 7Fh
(127°C) LUT
Lock Page 68
5Eh R/W LUT Temp 3
Setting 3
Stores the threshold level for the
External Diode 3 channel (or VIN3 or
TRIP_SET voltage or Pushed Temp 1
temp) that is associated with the Drive 3
value
7Fh
(127°C) LUT
Lock Page 68
5Fh R/W LUT Temp 4
Setting 3
Stores the threshold level for the
Internal Diode channel (or Pushed
Temp 2 temp) that is associated with the
Drive 3 value
7Fh
(127°C) LUT
Lock Page 68
60h R/W LUT Drive 4 Stores the fourth programmed drive
setting for the LUT BCh LUT
Lock Page 68
61h R/W LUT Temp 1
Setting 4 Stores the threshold level for the
External Diode 1 (or VIN1) channel that
is associated with the Drive 4 value 7Fh
(127°C) LUT
Lock Page 68
62h R/W LUT Temp 2
Setting 4 Stores the threshold level for the
External Diode 2 (or VIN2) channel that
is associated with the Drive 4 value 7Fh
(127°C) LUT
Lock Page 68
Table 6.1 EMC2105 Register Set (continued)
ADDR R/W REGISTER
NAME FUNCTION DEFAULT
VALUE LOCK PAGE
RPM-Based High Side Fan Controller with Hardware Thermal Sh utdown
Datasheet
SMSC EMC2105 43 Revision 1.78 (04-21-09)
DATASHEET
63h R/W LUT Temp 3
Setting 4
Stores the threshold level for the
External Diode 3 channel (or VIN3 or
TRIP_SET voltage or Pushed Temp 1
temp) that is associated with the Drive 4
value
7Fh
(127°C) LUT
Lock Page 68
64h R/W LUT Temp 4
Setting 4
Stores the threshold level for the
Internal Diode channel (or Pushed
Temp 2 temp) that is associated with the
Drive 4 value
7Fh
(127°C) LUT
Lock Page 68
65h R/W LUT Drive 5 Stores the fifth programmed drive
setting for the LUT A7h LUT
Lock Page 68
66h R/W LUT Temp 1
Setting 5 Stores the threshold level for the
External Diode 1 (or VIN1) channel that
is associated with the Drive 5 value 7Fh
(127°C) LUT
Lock Page 68
67h R/W LUT Temp 2
Setting 5 Stores the threshold level for the
External Diode 2 (or VIN2) channel that
is associated with the Drive 5 value 7Fh
(127°C) LUT
Lock Page 68
68h R/W LUT Temp 3
Setting 5
Stores the threshold level for the
External Diode 3 channel (or VIN3 or
TRIP_SET voltage or Pushed Temp 1
temp) that is associated with the Drive 5
value
7Fh
(127°C) LUT
Lock Page 68
69h R/W LUT Temp 4
Setting 5
Stores the threshold level for the
Internal Diode channel (or Pushed
Temp 2 temp) that is associated with the
Drive 5 value
7Fh
(127°C) LUT
Lock Page 68
6Ah R/W LUT Drive 6 Stores the sixth programmed drive
setting for the LUT 92h LUT
Lock Page 68
6Bh R/W LUT Temp 1
Setting 6 Stores the threshold level for the
External Diode 1 (or VIN1) channel that
is associated with the Drive 6 value 7Fh
(127°C) LUT
Lock Page 68
6Ch R/W LUT Temp 2
Setting 6 Stores the threshold level for the
External Diode 2 (or VIN2) channel that
is associated with the Drive 6 value 7Fh
(127°C) LUT
Lock Page 68
6Dh R/W LUT Temp 3
Setting 6
Stores the threshold level for the
External Diode 3 channel (or VIN3 or
TRIP_SET voltage or Pushed Temp 1
temp) that is associated with the Drive 6
value
7Fh
(127°C) LUT
Lock Page 68
6Eh R/W LUT Temp 4
Setting 6
Stores the threshold level for the
Internal Diode channel (or Pushed
Temp 2 temp) that is associated with the
Drive 6 value
7Fh
(127°C) LUT
Lock Page 68
6Fh R/W LUT Drive 7 Stores the seventh programmed drive
setting for the LUT 92h LUT
Lock Page 68
70h R/W LUT Temp 1
Setting 7 Stores the threshold level for the
External Diode 1 (or VIN1) channel that
is associated with the Drive 7 value 7Fh
(127°C) LUT
Lock Page 68
Table 6.1 EMC2105 Register Set (continued)
ADDR R/W REGISTER
NAME FUNCTION DEFAULT
VALUE LOCK PAGE
RPM-Based High Side Fan Controller with Hardware Thermal Shutdown
Datasheet
Revision 1.78 (04-21-09) 44 SMSC EMC2105
DATASHEET
71h R/W LUT Temp 2
Setting 7 Stores the threshold level for the
External Diode 2 (or VIN2) channel that
is associated with the Drive 7 value 7Fh
(127°C) LUT
Lock Page 68
72h R/W LUT Temp 3
Setting 7
Stores the threshold level for the
External Diode 3 channel (or VIN3 or
TRIP_SET voltage or Pushed Temp 1
temp) that is associated with the Drive 7
value
7Fh
(127°C) LUT
Lock Page 68
73h R/W LUT Temp 4
Setting 7
Stores the threshold level for the
Internal Diode channel (or Pushed
Temp 2 temp) that is associated with the
Drive 7 value
7Fh
(127°C) LUT
Lock Page 68
74h R/W LUT Drive 8 Stores the highest programmed drive
setting for the LUT 92h LUT
Lock Page 68
75h R/W LUT Temp 1
Setting 8 Stores the threshold level for the
External Diode 1 (or VIN1) channel that
is associated with the Drive 8 value 7Fh
(127°C) LUT
Lock Page 68
76h R/W LUT Temp 2
Setting 8 Stores the threshold level for the
External Diode 2 (or VIN2) channel that
is associated with the Drive 8 value 7Fh
(127°C) LUT
Lock Page 68
77h R/W LUT Temp 3
Setting 8
Stores the threshold level for the
External Diode 3 channel (or VIN3 or
TRIP_SET voltage or Pushed Temp 1
temp) that is associated with the Drive 8
value
7Fh
(127°C) LUT
Lock Page 68
78h R/W LUT Temp 4
Setting 8
Stores the threshold level for the
Internal Diode channel (or Pushed
Temp 2 temp) that is associated with the
Drive 8 value
7Fh
(127°C) LUT
Lock Page 68
79h R/W LUT Temp
Hysteresis Stores the hysteresis that is shared for
all temperature inputs 0Ah
(10°C) LUT
Lock Page 68
GPIO Registers
E0h R/W Muxed Pin
Configuration
Register Controls the pin function for the pins
muxed with GPIOs 01h No Page 70
E1h R/W GPIO Direction
Register Controls the GPIO direction for GPIO 1 00h No Page 70
E2h R/W GPIO Output
Configuration
Register Controls the output type GPIO 1 00h No Page 70
E3h R GPIO Input
Register Stores the inputs for GPIO 1 00h No Page 71
E4h R/W GPIO Output
Register Controls the output state of GPIO 1 00h No Page 71
E5h R/W GPIO Interrupt
Enable Register Enabled Interrupts for GPIO 1 00h No Page 71
Table 6.1 EMC2105 Register Set (continued)
ADDR R/W REGISTER
NAME FUNCTION DEFAULT
VALUE LOCK PAGE
RPM-Based High Side Fan Controller with Hardware Thermal Sh utdown
Datasheet
SMSC EMC2105 45 Revision 1.78 (04-21-09)
DATASHEET
During Power-On-Reset (POR), the default val ues are stored in the registers. A POR is initiated when
power is first applied to the part and the voltage on the VDD supply surpasses the POR level as
specified in the electrical characteristics. Any reads to undefined registers will return 00h. Writes to
undefined registers will not have an effect.
6.1.1 Lock Entries
The Lock Column describes the locking mechanism, if any, used for individual registers. All SWL
registers are Software Locked and therefore made read-only when the LOCK bit is set.
6.2 Temperature Data Registers
E6h R GPIO Status Indicates change of state for inputs on
GPIO 1 00h No Page 72
Lock Register
EF R/W Software Lock Locks all SWL registers 00h SWL Page 72
Revision Registers
FCh R Product Features Stores information about which pin
controlled product features are set 00h No Page 72
FDh R Product ID Stores the unique Product ID 1Bh No Page 73
FEh R Manufacturer ID Stores the Manufacturer ID 5Dh No Page 73
FFh R Revision Revision 02h No Page 73
Table 6.2 Temperature Data Registers
ADDR R/W REGISTER B7 B6 B5 B4 B3 B2 B1 B0 DEFAULT
00h R Internal Diode
High Byte Sign 64 32 16 8 4 2 1 00h
01h R Internal Diode
Low Byte 0.5 0.25 0.125 - - - - - 00h
02h R
External
Diode 1 High
Byte Sign 64 32 16 8 4 2 1 00h
VIN1 400 200 100 50 25 13.5 6.25 3.125 00h
03h R External
Diode 1 Low
Byte 0.5 0.25 0.125 - - - - - 00h
04h R
External
Diode 2 High
Byte Sign 64 32 16 8 4 2 1 00h
VIN2 400 200 100 50 25 13.5 6.25 3.125 00h
Table 6.1 EMC2105 Register Set (continued)
ADDR R/W REGISTER
NAME FUNCTION DEFAULT
VALUE LOCK PAGE
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Datasheet
Revision 1.78 (04-21-09) 46 SMSC EMC2105
DATASHEET
The temperature measurement range is from -64°C to +128°C. The data format is a signed two’s
complement number as shown in Table 6.3.
APPLICATION NOTE: When each of the External Diode 1, External Diode 2, or External Diode 3 channels are
configured as a voltage input, the voltage data will be stored in the corresponding data
register. Each bit weight represents XmV of resolution so that the final voltage can be
determined by adding the ap propriately set bits together. This data will be compared against
the limits normally (see Section 6.17).
05h R External
Diode 2 Low
Byte 0.5 0.25 0.125 - - - - - 00h
06h R
External
Diode 3 High
Byte Sign 64 32 16 8 4 2 1 00h
VIN3 400 200 100 50 25 13.5 6.25 3.125 00h
07h R External
Diode 3 Low
Byte 0.5 0.25 0.125 - - - - - 00h
08h R External
Diode 4 High
Byte Sign 64 32 16 8 4 2 1 00h
09h R External
Diode 4 Low
Byte 0.5 0.25 0.125 - - - - - 00h
Table 6.3 Temperature Data Format
TEMPERATURE (°C) BINARY HEX (AS READ BY
REGISTERS)
Diode Fault 1000_0000_000b 80_00h
-63.875 1100_0000_001b C0_20h
-63 1100_0001_000b C1_00h
-1 1111_1111_000b FF_00h
-0.125 1111_1111_111b FF_E0h
0 0000_0000_000b 00_00h
0.125 0000_0000_001b 00_20h
1 0000_0001_000b 01_00h
63 0011_1111_000b 3F_00h
64 0100_0000_000b 40_00h
65 0100_0001_000b 41_00h
Tab le 6.2 Temperature Data Registers (continued)
ADDR R/W REGISTER B7 B6 B5 B4 B3 B2 B1 B0 DEFAULT
RPM-Based High Side Fan Controller with Hardware Thermal Sh utdown
Datasheet
SMSC EMC2105 47 Revision 1.78 (04-21-09)
DATASHEET
6.3 Critical/Thermal Shutdown Temperature Registers
The Critical/Thermal Shutdown Temperature Register is a read-only register that stores the Voltage
Programmable Threshold temperature used in the Thermal / Critical Shutdown circuitry. The contents
of the register reflect the calculated temperature based on the TRIP_SET voltage. This register is
updated at the end of every monitoring cycle based on the current value of the TRIP_SET voltage.
The data format is shown in Table 6.5.
6.4 Pushed Temperature Registers
127 0111_1111_000b 7F_00h
127.875 0111_1111_111b 7F_E0h
Table 6.4 Critical/Thermal Shutdown Temperature Registers
ADDRR/WREGISTER B7B6B5B4B3B2B1B0DEFAULT
0Ah R Critical/Thermal
Shutdown
Temperature 128 64 32 16 8 4 2 1 7Fh
(+127°C)
Table 6.5 Critical / Thermal Shutdown Data Format
TEMPERATURE (°C) BINARY HEX
0 0000_0000b 00h
1 0000_0001b 01h
63 0011_1111b 3Fh
64 0100_0000b 40h
65 0100_0001b 41h
127 0111_1111b 7Fh
130 1000_0010b 82h
150 1001_0110b 96h
Tab le 6.6 Pushed Temperature Register
ADDR R/W REGISTER B7 B6 B5 B4 B3 B2 B1 B0 DEFAULT
0Ch R/W Pushed
Temperature 1 Sign 64 32 16 8 4 2 1 00h
0Dh R/W Pushed
Temperature 2 Sign 64 32 16 8 4 2 1 00h
Table 6.3 Temperature Data Format (continued)
TEMPERATURE (°C) BINARY HEX (AS READ BY
REGISTERS)
RPM-Based High Side Fan Controller with Hardware Thermal Shutdown
Datasheet
Revision 1.78 (04-21-09) 48 SMSC EMC2105
DATASHEET
The Pushed Temperature Registers store user programmed temperature values that can be used by
the look-up table to update the fan control algorithm. Data written in these registers is not compared
against any limits and must match the data format shown in Table 6.3.
6.5 Voltage Registers
The Voltage Registers hold the data read from the TRIP_SET voltage input. The TRIP_SET voltage is
stored whether the TRIP_SET is u sed to set the The rmal / C riti cal Shutdown temp erature or configu red
to act as the VIN4 input.
Each bit weight represents mV of reso lution so that the final voltage can be determi ned by adding the
appropriately set bits together.
6.6 Beta Configuration Registers
The Beta Configuration Registers control advanced temperature measurement features for each
External Diode channel. The Beta Configuration Registers are software locked. The External Diode 1
Beta Configuration Register Is hardware locked if the SHDN_SEL pin is not set to disable the Critical
/ Thermal Shutdown functionality (see Table 6.1).
Bit 4 - AUTO - Enables the Automatic Beta detection algorithm.
‘0’ - The Automatic Beta detection algorithm is disabled. The BETAx[3:0] bit settings will be used
to control the beta compensation circuitry.
‘1’ (default) - The Automatic Beta detection algorithm is enabled. The circuitry will automatically
detect the transistor type and beta values and configure the BETAx[3:0] bits for optimal
performance.
Bits 3 - 0 - BETAx[3:0] - hold a value that corresponds to a range of betas that the Beta Compensation
circuitry can compensate for. These four bits will always show the current beta setting used by the
circuitry. If the AUTO bit is set (default), then these bits may updated by the device with every
temperature conversion. If the AUTO bit is not set, then the value of these bits is used to drive the
Table 6.7 TripSet Voltage Register
ADDRR/W REGISTER B7B6B5B4B3B2B1B0DEFAULT
10h R TRIP_SET
Voltage / VIN4
Voltage 400 200 100 50 25 13.5 6.25 3.125 FFh
Table 6.8 Beta Configuration Registers
ADDR R/W REGISTER B7 B6 B5 B4 B3 B2 B1 B0 DEFAULT
14h R/W External Diode 1
Beta
Configuration - - - AUTO BETA1[3:0] 10h
15h R/W External Diode 2
Beta
Configuration - - - AUTO BETA2[3:0] 10h
16h R/W External Diode 3
Beta
Configuration - - - AUTO BETA3[3:0] 10h
RPM-Based High Side Fan Controller with Hardware Thermal Sh utdown
Datasheet
SMSC EMC2105 49 Revision 1.78 (04-21-09)
DATASHEET
beta compensation circuitry. In this case, these bits should be set with a value corresponding to the
lowest expected value of beta for the PNP transistor being used as a temperature sensing device.
See Table 6.9 for supported beta ranges. A value of 1111b indicates that the beta compensation
circuitry is disabled. In this condition, the diode channels will function with default current levels and
will not automatically adjust for beta variation. This mode is used when measuring a discrete 2N3904
transistor or AMD thermal diode.
All of the Beta Configuration Registers are Software Locked.
6.7 REC Configuration Register
The REC Configuration Register determines whether Resistance Error Correction is used for each
external diode channel. The REC Configuration Register is software locked.
Table 6.9 Beta Compensation Look Up Table
AUTO
BETAX[3:0]
MINIMUM BETA3210
00000 0.050
00001 0.066
00010 0.087
00011 0.114
00100 0.150
00101 0.197
00110 0.260
00111 0.342
01000 0.449
01001 0.591
01010 0.778
01011 1.024
01100 1.348
01101 1.773
01110 2.333
01111 Disabled
1 X X X X Automatically detected
Table 6.10 REC Configuration Register
ADDRR/W REGISTER B7B6B5B4B3B2B1B0DEFAULT
17h R/W REC
Configuration - - - - - REC3 REC2 REC1 07h
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Datasheet
Revision 1.78 (04-21-09) 50 SMSC EMC2105
DATASHEET
Bit 2 - REC3 - Controls the Resistive Error Correction functionality of External Diode 3 and External
Diode 4 (if APD is enabled, see Section 6.9)
‘0’ - the REC functionality for External Diode 3 is disabled
‘1’ (default) - the REC functionality for External Diode 3 is enabled.
Bit 1 - REC2 - Controls the Resistive Error Correction functionality of External Diode 2.
‘0’ - the REC functionality for External Diode 2 is disabled
‘1’ (default) - the REC functionality for External Diode 2 is enabled.
Bit 0 - REC1 - Controls the Resistive Error Correction functionality of External Diode 1. This bit is
locked if the SHDN_SEL pin is not pulled to VDD (see Table 6.1).
‘0’ - the REC functionality for External Diode 1 is disabled
‘1’ (default) - the REC functionality for External Diode 1 is enabled.
6.8 Critical Temperature Limit Registers
The Critical Temperature Limit Regi sters store the Critical Te mperature Limit. At power up, none of the
respective channels are linked to the SYS_SHDN pin or the Hardware set Thermal/Critical Shutdown
circuitry.
Whenever one of the regi sters is updated, two things occur. First, the register is locked so that it cannot
be updated again without a power on reset. Second, the respective temperature channel is linked to
the SYS_SHDN pin and the Hardware set Thermal/Critical Shutdown Circuitry. At this point, if the
measured temperature channel exceeds the Critical limit, the SYS_SHDN pin will be asserted, the
appropriate bit set in the Tcrit Status Register, and the TCRIT bit in the Interrupt Status Register will
be set.
6.9 Configuration Register
Table 6.11 Limit Registers
ADDR R/W REGISTER B7 B6 B5 B4 B3 B2 B1 B0 DEFAULT
19h R/W
once External Diode
1 Tcrit Limit Sign 64 32 16 8 4 2 1 64h
(+100°C)
1Ah R/W
once External Diode
2 Tcrit Limit Sign 64 32 16 8 4 2 1 64h
(+100°C)
1Bh R/W
once External Diode
3 Tcrit Limit Sign 64 32 16 8 4 2 1 64h
(+100°C)
1Ch R/W
once External Diode
4 Tcrit Limit Sign 64 32 16 8 4 2 1 64h
(+100°C)
1Dh R/W
once Internal Diode
Tcrit Limit Sign 64 32 16 8 4 2 1 64h
(+100°C)
Table 6.12 Configuration Register
ADDR R/W REGISTER B7 B6 B5 B4 B3 B2 B1 B0 DEFAULT
20h R/W Configuration MASK - - SYS4 SYS3 SYS2 SYS1 APD 00h
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Datasheet
SMSC EMC2105 51 Revision 1.78 (04-21-09)
DATASHEET
The Configuration Register controls the basic functionality of the EMC2105. The bits are described
below. The Configuration Register is software locked.
Bit 7 - MASK - Blocks the ALERT# pin from being asserted.
‘0’ (default) - The ALERT# pin is unmasked. If any bit in either status register is set, the ALERT#
pins will be asserted (unless individually masked via the Mask Register)
‘1’ - The ALERT# pin is masked and will not be asserted.
Bit 4 - SYS4 - Enables the high temperature limit for the External Diode 4 channel to trigger the Cr itical
/ Thermal Shutdown circuitry (see Section 6.1). This bit is ignored if th e DP3 / DN3 pins are configured
to measure a voltage input. In this case, the External Diode 4 channel is disabled and not compared
against any limits.
‘0’ (default) - the External Diode 4 channel high limit will not be linked to the SYS_SHDN# pin. If
the temperature exceeds the limit, the ALERT# pin will be asserted normally.
‘1’ - the External Diode 4 channel high limit will be linked to the SYS_SHDN# pin. If the temperature
exceeds the limit then the SYS_SHDN# pin will be asserted. The SYS_SHD N# pin w ill be release d
when the temperature drops below the high limit. The ALERT# pin will be asserted and released
normally.
Bit 3 - SYS3 - Enables the high temperature limit for the External Diode 3 channel to trigger the Cr itical
/ Thermal Shutdown circuitry (see Section 6.1).
Bit 2 - SYS2 - Enables the high temperature limit for the External Diode 2 channel to trigger the Cr itical
/ Thermal Shutdown circuitry (see Section 6.1).
Bit 1 - SYS1 - Enables the high temperature limit for the External Diode 1 channel to trigger the Cr itical
/ Thermal Shutdown circuitry (see Section 6.1).
Bit 0 - APD - This bit enables the Anti-parallel diode functionality on the External Diode 3 pins (DP3
and DN3).
‘0’ (default) - The Anti-parallel diode functionality is disabled. The Exte rnal Diode 3 cha nnel can be
configured for any type of diode
‘1’ - The Anti-parallel diode functionality is en abled. Both the External Diode 3 and 4 channels are
configured to support a diode or diode connected transistor (such as a 2N3904).
APPLICATION NOTE: When the APD diode is enabled, there will be a delay of a full temperature update before
any comparisons and functionality associated with the External Diode 4 channel will be
implemented. This includes the SYS4 bit operation, limit comparisons, and look up table
comparisons.
6.10 Configuration 2 Register
The Configuration 2 Register controls conversion rate of the temperature monitoring as well as the
fault queue. This register is software locked.
Bit 6 - DIS_DYN - Disables the Dynamic Averaging Feature.
‘0’ (default) - The Dynamic Averaging functi on is enabled. The conversion time for all temperature
channels is scaled based on the chosen conversion rate to maximize accuracy and immunity to
random temperature measurement variation.
Table 6.13 Configuration 2 Register
ADDR R/W REGISTER B7 B6 B5 B4 B3 B2 B1 B0 DEFAULT
21h R/W Config 2 - DIS_
DYN DIS_
TO DIS_
AVG QUEUE[1:0] CONV[1:0] 0Eh
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‘1’ - The Dynamic Averaging function is disable d. The conversio n time for all temperature ch annels
is fixed regardless of the chosen conversion rate.
Bit 5 - DIS_TO - Disables the SMBus time out function for the SMBus client (if enabled).
‘0’ (default) - The SMBus time out function is enabled.
‘1’ - The SMBus time out function is disabled allowing the device to be fully I2C compliant.
Bit 4 - DIS_AVG - Disables digital averaging of the External Diode 1 channel.
‘0’ (default) - The External Diode 1 channel has digital averaging enabled. The temperature data
is the average of the previous four measurements.
‘1’ - The External Diode 1 channel has digital averagin g disabled. The temperature da ta is the last
measured data.
Bits 3-2 - QUEUE[1:0] - Determines the number of consecutive out of limit conditions that are
necessary to trigger an interrupt. Each measurement channel has a separate fault queue associated
with the high limit, low limit, and diode fault condition except the internal diode.
The Critical / Thermal Shutdown temperature has a separate fault queue that applies to the selected
hardware shutdown channel (see Section 6.1.1) when compared against the threshold set by the
TRIP_SET pin.
APPLICATION NOTE: If the fault queue for any channel is currently active (i.e. an out of limit condition has been
detected and caused the fault queue to increment) then changing the settings will not take
effect until the fault queue is zeroed. This occurs by the ALERT# pin asserting or the out of
limit condition being removed.
Bit 1 - 0 - CONV[1:0] - determi nes the conversion rate of the temperature monitoring. This conversion
rate does not affect the fan driver. The supply current from VDD_3V is nominally dependent upon the
conversion rate and the average current will increase as the conversion rate increases.
Table 6.14 Fault Queue
QUEUE[1:0]
NUMBER OF CONSECUTIVE OUT OF LIMIT CONDITIONS 10
0 0 1 (disabled)
01 2
10 3
1 1 4 (default)
Table 6.15 Conversio n Rate
CONV[1:0]
CONVERSION RATE
TEMPERATURE OVER SAMPLING
FROM 11 BITS
1 0 DYN_DIS = ‘0’ DYN_DIS = ‘1’
0 0 1 / sec x8 x1
0 1 2 / sec x4 x1
1 0 4 / sec (default) x2 x1
1 1 Continuous x1 x1
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6.11 Configuration 3 Register
The Configuration 3 Register controls the fou r voltage input channels. This register is software locked.
Bit 6 - VIN4_INV - Determines whether the VIN4 channel data is inverted.
‘0’ (default) - The VIN4 channel data is not inverted.
‘1’ - The VIN4 channel data is inverted. The data presented to th e reading registers and compared
against the limits is determined as FFh - the measured input voltage.
APPLICATION NOTE: If the TRIP_SET / VIN4 pin is configured to be used to set the Critical / Thermal Shutdown
temperature associated with the External Diode 1 channel, then this bit cannot be set.
Bit 5 - VIN3_EN - Enables the voltage mode on the External Diode 3 channel.
‘0’ (default) - The External Diode 3 channel operates as a diode channel.
‘1’ - The External Diode 3 channel operates as a voltage input. The DP3 / DN4 / VREF_T3 pin
acts as a reference output voltage and the DN3 / DP4 /. VIN3 pin acts as a voltage input. This
overrides the APD bit in the Configuration 1 Register (20h).
Bit 4 - VIN3_INV - Determines whether the VIN3 channel data is inverted.
Bit 3 - VIN2_EN - Enables the voltage mode on the External Diode 2 channel.
Bit 2 - VIN2_INV - Determines whether the VIN2 channel data is inverted.
Bit 1 - VIN1_EN - Enables the voltage mode on the External Diode 1 channel.
Bit 0 - VIN1_INV - Determines whether the VIN1 channel data is inverted.
APPLICATION NOTE: If the TRIP_SET / VIN4 pin is configured to be used to set the Critical / Thermal Shutdown
temperature associated with the External Diode 1 channel, then neither Bit 1 nor Bit 0 can
be set.
6.12 Interrupt Status Register
The Interrupt Status Register reports the operating condition of the EMC2105. If any of the bits are set
to a logic ‘1’ (other than TSD an d HWS) then the ALERT# pin will be asserted low if the corresponding
channel is enabled. Reading from the status register clears all status bits if the error conditions is
removed. If there are no set status bits, then the ALERT# pin will be released.
The bits that cause the ALERT# pin to be asserted can be masked based on the channel they are
associated with unless stated otherwise.
Table 6.16 Configuration 3 Register
ADDR R/W REGISTER B7 B6 B5 B4 B3 B2 B1 B0 DEFAULT
22h R/W Config 3 - VIN4_I
NV VIN3
_EN VIN3
_INV VIN2
_EN VIN2
_INV VIN1
_EN VIN1
_INV 00h
Table 6.17 Interrupt Status Register
ADDR R/W REGISTER B7 B6 B5 B4 B3 B2 B1 B0 DEFAULT
23h R-C Interrupt
Status
Register - TSD TCRIT GPIO FAN HIGH LOW FAULT 00h
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Bit 6 - TSD - This bit is set to ‘1’ if the internal Thermal Sh utdown (TSD) circuit trips indicating that the
die temperature has exceeded its threshold. When this bit is set, it will not cause the ALERT# pin to
be asserted however will coincide with the SYS_SHDN# pin being asserted. This bit is cleared when
the register is read and the error condition has been removed.
Bit 5 - TCRIT - This bit is set to ‘1’ whenever the any bit in the Tcrit Status Register is set. This bit is
automatically cleared when the Tcrit Status Register is cleared.
Bit 4 - GPIO - This bit is set to ‘1’ if any of the bits in the GPIO Status Registers are set.
Bit 3 - FAN - This bit is set to ‘1’ if any bit in the Fan Status Register is set. This bit is automatically
cleared when the Fan Status Register is read and the bits are cleared.
Bit 2 - HIGH - This bit is set to ‘1’ if any bit in the High Status Register is set. This bit is automatically
cleared when the High Status Register is read and the bits are cleared.
Bit 1- LOW - This bit is set to ‘1’ if any bit in the Low Status Register is set. This bit is automatically
cleared when the Low Status Register is read and the bits are cleared.
Bit 0 - FAULT - This bit is set to ‘1’ if any bit in the Diode Faul t Register is set. This bit is automatica lly
cleared when the Diode Fault Register is read and the bits are cleared.
6.13 Error Status Registers
The Error Status Registers report the specific error condition for all measure ment chann els with limits.
If any bit is set in the High, Low, or Diode Fault Status register, the corresponding High, Low, or Fault
bit is set in the Interrupt Status Register.
Reading the Interrupt Status Register does not clear the Error Status bit. Reading from any Error Status
Register that has bits set will clear the register and the corresponding bit in the Interrupt Status
Register if the error condition has been removed. If the error condition is persistent, reading the Error
Status Registers will have no affect.
If any of the External Diode 1, External Diode 2, or External Diode 3 channels are configured as a
voltage input, then the corresponding tempera ture cha nne l status bit will b e set if the measured vol tage
exceeds the high limit or falls below the low limit. In this condition, a diode fault will be ignored.
APPLICATION NOTE: If any of the External Diode 1, 2, or 3 channels are configured as a voltage input and
thermistor or other voltage source is used on the corresponding pins at device power up,
then the corresponding diode fault status bits will be set. The status bits should be cleared
prior to enabling the interrupts to avoid erroneous alert conditions.
Table 6.18 Error Status Regi ste r
ADDR R/W REGISTER B7 B6 B5 B4 B3 B2 B1 B0 DEFAULT
1Fh R-C Tcrit Status HWS - - EXT4_
CRIT EXT3_
CRIT EXT2_
CRIT EXT1
_CRIT INT_
CRIT 00h
24h R-C High Status - - VOLT
4_HI EXT4_
HI EXT3_
HI EXT2_
HI EXT1
_HI INT_
HI 00h
25h R-C Low Status - - VOLT
4_LO EXT4_
LO EXT3_
LO EXT2_
LO EXT1
_LO INT_L
O00h
26h R-C Diode Fault - - - EXT4_
FLT EXT3_
FLT EXT2_
FLT EXT1
_FLT -00h
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6.13.1 Tcrit Status Register
The Tcrit Status Register stores the event that caused the SYS_SHDN# pin to be asserted. Each of
the temperature channels must be associated with the SYS_SHDN# pin before they can be set (see
Section 6.8). Once the SYS_SHDN# pin is asserted, it will be released when the temperature drops
below the threshold level however the individual status bit will not be cleared until read.
Bit 7 - HWS - This bit is set if the hardware set temperature channel meets or exceeds the temperature
threshold determined by the TRIP_SET voltage.
6.14 Fan Status Register
The Fan Status Register contains the status bits associated with each fan driver. This register is
cleared when read if the error condition has been removed.
Bit 7 - WATCH - This bit is asserted ‘1’ if the host has not programmed the fan driver within four (4)
seconds after power up.
Bit 6 - DRIVE_FAIL - Indicates that the RPM based Fan Speed Control Algo rithm cannot drive the Fan
to the desired target setting at maximu m drive . Th is bit can be masked from assertin g the ALERT# pin.
‘0’ - The RPM based Fan Speed Control Algorithm can drive the Fan to the desired target setting.
‘1’ - The RPM based Fan S peed Control Algorithm cannot drive the Fan to the desired target setting
at maximum drive.
Bit 5 - FAN_SHORT - This bit is asserted ‘1’ if the High Side Fan Driver detects an over current
condition that lasts for longer than 2 seconds.
Bit 1- FAN_SPIN- This bit is asserted ‘1’ if the Spin up Routine for the Fan cannot detect a valid
tachometer reading within its maximum time window. This bit can be masked from asserting the
ALERT# pin.
Bit 0 - FAN_STALL1 - This bit is asserted ‘1’ if the tachometer measurement on the Fan detects a
stalled fan. This bit can be masked from asserting the ALERT# pin.
6.15 Interrupt Enable Register
The Interrupt Enable Register controls the masking for each temperature channel. When a channel is
masked, it will not cause the ALERT# pin to be asserted when an error condition is detected.
Bit 5 - VOLT4_INT_EN - Allows the Voltage Input 4 channel to assert the ALERT# pin.
‘0’ (default) - The ALERT# pin will be not be asserted for any error condition associated with
Voltage Channel 4 (TRIP_SET / VIN4).
Table 6.19 Fan S tatus Regist e r
ADDR R/W REGISTER B7 B6 B5 B4 B3 B2 B1 B0 DEFAULT
27h R-C Fan Status
Register WATCH - DRIVE
_FAIL FA N_
SHORT --
FAN_
SPIN FAN_
STALL 00h
Table 6.20 Interrupt Enable Register
ADDR R/W REGISTER B7 B6 B5 B4 B3 B2 B1 B0 DEFAULT
28 R/W Interrupt
Enable --
VOLT4_I
NT_EN EXT4_I
NT_EN EXT3_I
NT_EN EXT2_I
NT_EN EXT1_I
NT_EN INT_IN
T_EN 00h
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‘1’ - The ALERT# pin will be asserted for an error condition associated with Voltage Channel 4.
Bit 4 - EXT4_INT_EN - Allows the External Diode 4 channel to assert the ALERT# pin.
‘0’ (default) - The ALERT# pin will be not be asserted for any error condition associated with
External Diode 4.
‘1’ - The ALERT# pin will be asserted for an error condition associated with External Diode 4.
Bit 3 - EXT3_INT_EN - Allows the External Diode 3 or VIN3 channel to assert the ALERT# pin.
‘0’ (default) - The ALERT# pin will not be asserted for any error condition associated with External
Diode 3 or VIN3 channels.
‘1’ - The ALERT# pin will be asserted for an error condition associated with External Diode 3 or
VIN3 channels.
Bit 2 - EXT2_INT_EN - Allows the External Diode 2 or VIN2 channel to assert the ALERT# pin.
‘0’ (default) - The ALERT# pin will not be asserted for any error condition associated with External
Diode 2 or VIN2 channels.
‘1’ - The ALERT# pin will be asserted for an error condition associated with External Diode 2 or
VIN2 channels.
Bit 1 - EXT1_INT_EN - Allows the External Diode 1 or VIN1 channel to assert the ALERT# pin.
‘0’ (default) - The ALERT# pin will not be asserted for any error condition associated with External
Diode 1 or VIN1 channels.
‘1’ - The ALERT# pin will be asserted for an error condition associated with External Diode 1 or
VIN1 channels.
Bit 0 - INT_INT_EN - Allows the Internal Diode channel to assert the ALERT# pin.
‘0’ (default) - The ALERT# pin will not be asserted for any error condition associated with the
Internal Diode.
‘1’ - The ALERT# pin will be asserted for an error condition associated with the Internal Diode.
6.16 Fan Interrupt Enable Register
The Fan Interrupt Enable controls the masking for each Fan channel. When a channel is enabled, it
will cause the ALERT# pin to be asserted when an error condition is detected.
Bit 1 - SPIN_INT_EN - Allows the FAN_SPIN bit to assert the ALERT# pin.
‘0’ (default) - the FAN_SPIN bit will not assert the ALERT# pin though it will still update th e Status
Register normally.
‘1’ - the FAN_SPIN bit will assert the ALERT# pin.
Bit 0 - STALL_INT_EN - Allows the FAN_STALL bit or DRIVE_FAIL bit to assert the ALERT# pin.
‘0’ (default) - the FAN_STALL bit or DRIVE_FAIL bit will not assert the ALERT# pin though will still
update the Status Register normally.
‘1’ - the FAN_STALL or DRIVE_FAIL bit will assert the ALERT# pin if set.
Table 6.21 Fan Interrupt Enable Register
ADDRR/WREGISTERB7B6B5B4 B3 B2 B1B0DEFAULT
29h R/W Fan
Interrupt
Enable ---- - -
SPIN_
INT_EN STALL_
INT_EN 00h
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6.17 Limit Registers
The EMC2105 contains high limits for all temperature channels and voltage channels. If any
measurement meets or exceeds the high limit then the appropriate status bit is set and the ALERT#
pin are asserted (if enabled).
APPLICATION NOTE: If any of the External Diode 1, External Diode 2, External Diode 3 is configured to operate
as a voltage input, then the corresponding temperature high and low limit registers are
compared against the measured voltage. The data format is the same as the measured
voltage and these registers should be updated accordingly.
Additionally, the EMC2105 contains low li mits for all temperature channels. If the temperature channel
drops below the low limit, then the appropriate status bit is set and the ALERT# pin are asserted (if
enabled).
All Limit Registers are Software Locked.
Table 6.22 Limit Registers
ADDR R/W REGISTER B7 B6 B5 B4 B3 B2 B1 B0 DEFAULT
30h R/W External Diode
1 High Limit Sign 64 32 16 8 4 2 1 55h
(+85°C)
31h R/W External Diode
2 High Limit Sign 64 32 16 8 4 2 1 55h
(+85°C)
32h R/W External Diode
3 High Limit Sign 64 32 16 8 4 2 1 55h
(+85°C)
33h R/W External Diode
4 High Limit Sign 64 32 16 8 4 2 1 55h
(+85°C)
34h R/W Internal Diode
High Limit Sign 64 32 16 8 4 2 1 55h
(+85°C)
35h R/W VIN4 High
Limit 752.9 376.5 188.2 94.12 47.06 23.53 11.76 5.88 FFh
(0.8V)
38h R/W External Diode
1 Low Limit Sign 64 32 16 8 4 2 1 00h
(0°C)
39h R/W External Diode
2 Low Limit Sign 64 32 16 8 4 2 1 00h
(0°C)
3Ah R/W External Diode
3 Low Limit Sign 64 32 16 8 4 2 1 00h
(0°C)
3Bh R/W External Diode
4 Low Limit Sign 64 32 16 8 4 2 1 00h
(0°C)
3Ch R/W Internal Diode
Low Limit Sign 64 32 16 8 4 2 1 00h
(0°C)
3Dh R/W VIN 4 Low
Limit 752.9 376.5 188.2 94.12 47.06 23.53 11.76 5.88 00h
(0V)
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6.18 Fan Setting Register
The Fan Setting Register always displays the current setting of the Fan Driver. Reading from either
register will report the current fan speed setting of the appropriate fan drive r regardless of the operating
mode. Therefore it is possible that reading from this register will not report data that was previously
written into this register.
While the RPM based Fan Speed Control Algorithm or the Look Up Table are active (or both), then
the register is read only. Writing to the register will have no affect and the data will not be stored.
If both the RPM based Fan Control Algorithm and the Look Up Table are disabled, then the register
will be set with th e previous value that was used. T he register is read / wr ite and writing to this register
will affect the fan speed.
The contents of the register represent the we ighting of each bit in determining the final output voltage.
The output drive for the High Side Fan Driver output is given by Equation [2].
6.19 Fan Configuration 1 Register
The Fan Configuration 1 Register controls the general opera tion of the RPM based Fan Speed Control
Algorithm used for the Fan driver.
Bit 7 - EN_ALGO - enables the RPM based Fan Speed Control Algorithm. This bit is set and cleared
automatically when the LUT_LOCK bit is set based on the setting of the TACH / DRIVE bit (see
Section 6.29). When the LUT_LOCK bit is cleared, then setting this bit will enable the FSC without
using the Look Up Table.
‘0’ - (default) the control circuitry is disabled and the fan driver output is determined by the Fan
Driver Setting Register.
‘1’ - the control circuitry is enabled and the Fan Driver output will be automatically updated to
maintain the programmed fan speed as indicated by the TACH Target Register.
Bits 6- 5 - RANGE[1:0] - Adjusts the range of reported and programmed tachometer reading values.
The RANGE bits determine the weighting of all TACH values (including the Valid TACH Count, TACH
Target, and TACH reading) as shown in Table 6.25.
Tabl e 6.23 Fan Driver Setting Register
ADDR R/W REGISTER B7 B6 B5 B4 B3 B2 B1 B0 DEFAULT
40h R/W Fan Setting 128 64 32 16 8 4 2 1 00h
[2]
Table 6.24 Fan Configuration 1 Register
ADDR R/W REGISTER B7 B6 B5 B4 B3 B2 B1 B0 DEFAULT
42h R/W Fan
Configuration
1EN_
ALGO RANGE[1:0] EDGES[1:0] UPDATE[2:0] 2Bh
Drive VALUE
255
---------------------
⎝⎠
⎛⎞
VDD_5V×=
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Bits 4-3 - EDGES[1:0] - determines the minimum number of edges that must be detected on the
TACHx signal to determine a single rotation. A typical fan measured 5 edges (for a 2-pole fan). For
more accurate tachometer measurement, the min imum number of edges measured may be increased.
Increasing the number of edges measured with respect to the number of poles of the fan will cause
the TACH Reading registers to indicate a fan speed that is higher or lower than the actual speed. In
order for the FSC Algorithm to operate correctly, the TACH Target must be updated by the user to
accommodate this shift. The Effective Tach Mu ltiplier shown in Table 6.26 is used as a direct multiplier
term that is applied to the Actual RPM to achieve the Reported RPM. It should only be applied if the
number of edges measured does not match the number of edges expected based on the number of
poles of the fan (which is fixed for any given fan).
Contact SMSC for recommended settings when using fans with more or less than 2 poles.
Bit 2-0 - UPDATE - determines the base time between fan driver updates. The Update Time, along
with the Fan Step Register, is u sed to control the ramp rate of the drive resp onse to provide a cleaner
transition of the actual fan operation as the desired fan speed changes. The Update Time is set as
shown in Table 6.27.
Table 6.25 Range Decod e
RANGE[1:0] REPORTED MINIMUM
RPM TACH COUNT
MULTIPLIER10
005001
0 1 1000 (default) 2
1 0 2000 4
1 1 4000 8
Table 6.26 Minimum Edges for Fan Rotation
EDGES[1:0] MINIMUM TACH
EDGES NUMBER OF FAN POLES
EFFECTIVE TACH
MULTIPLIER (BASED ON 2
POLE FANS)10
00 3 1 pole 0.5
0 1 5 2 poles (default) 1
1 0 7 3 poles 1.5
11 9 4 poles 2
Table 6.27 Update Time
UPDATE[2:0]
UPDATE TIME 21 0
00 0 100ms
00 1 200ms
01 0 300ms
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6.20 Fan Configuration 2 Register
The Fan Configuration 2 Register controls the tachometer measurement and advanced features of the
RPM based Fan Speed Control Algorithm.
Bit 6 - EN_RRC - Enables ramp rate control when the corresponding fan driver is operated i n the Direct
Setting Mode or the Direct Setting with LUT mode.
‘0’ (default) - Ramp ra te control is disabled. When the fan drive r is ope rati ng i n Direct Setting mode
or Direct Setting with LUT mode, the fan setting will instantly transition to the next programmed
setting.
‘1’ - Ramp rate control is e nabled. W hen the fa n d river is operating in Direct Setting mode or Direct
Setting with LUT mode, the fan drive setting will foll ow the ra mp rate controls as determined by the
Fan Step and Update Time settings. The maximum fan drive setting step is capp ed at the Fan St ep
setting and is updated based on the Update Time as given by Table 6.27.
Bit 5 - GLITCH_EN - Disables the low pass glitch filter that removes high frequency noise injected on
the TACHx pin. If the LOWDRIVE bit is set, this bit is ignored and the filter is automatically disabled.
‘0’ - The glitch filter is disabled.
‘1’ (default) - The glitch filter is enabled.
Bits 4 - 3 - DER_OPT[1:0] - Control some of the advanced options that affect the derivative portion of
the RPM based Fan Speed Control Algorithm as shown in Table 6.29.
0 1 1 400ms (default)
10 0 500ms
10 1 800ms
1 1 0 1200ms
1 1 1 1600ms
Table 6.28 Fan Configuration 1 Register
ADDR R/W REGISTER B7 B6 B5 B4 B3 B2 B1 B0 DEFAULT
43h R/W Fan
Configuration
2-EN_
RRC GLITCH
_EN1 DER_OPT [1:0] ERR_RNG[1:0] - 38h
Table 6.27 Update Time (continued)
UPDATE[2:0]
UPDATE TIME 21 0
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Bit 2 - 1 - ERR_RNG[1:0] - Control some of the advanced options that affect the error window. When
the measured fan spe ed is within the programmed error windo w around the target speed, then the fan
drive setting is not updated. The algorithm will continue to monitor the fan speed and calculate
necessary drive setting changes based on the error, however these changes are ignored.
6.21 Gain Register
The Gain Register stores the gain terms used by the proportional and integral portions of each of the
RPM based Fan Speed Control Algorithms. These gain terms are used as the KD, KI, and KP gain
terms in a classic PID control solution.
Table 6.29 Derivative Options
DER_OPT[1:0]
OPERATION10
0 0 No derivative options used
01
Basic derivative. The derivative of the error from
the current drive setting and the target is added
to the iterative Fan Drive Register setting (in
addition to proportional and integral terms)
10
Step derivative. The derivative of the error from
the current drive setting and the target is added
to the iterative Fan Drive Register setting and is
not capped by the Fan Step Register.
11
Both the basic derivative and the step derivative
are used effectively causing the derivative term to
have double the effect of the derivative term
(default).
Table 6.30 Error Range Options
ERR_RNG[1:0]
OPERATION10
0 0 0 RPM (default)
0 1 50 RPM
1 0 100 RPM
1 1 200 RPM
Table 6.31 Gain Register
ADDR R/W REGISTER B7 B6 B5 B4 B3 B2 B1 B0 DEFAULT
45h R/W Gain Register - - GAIND[1:0] GAINI[1:0] GAINP[1:0] 2Ah
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6.22 Fan Spin Up Configuration Register
The Fan Spin Up Configuration Register controls the settings of Spin Up Routine. The Fan Spin Up
Configuration Register is software locked.
Bit 7 - 6 - DRIVE_FAIL_CNT[1:0] - Determines how many update cycles are used for the Drive Fail
detection function as shown in Table 6.34. This circuitry determines whether the fan can be driven to
the desired tach target.
Bit 5 - NOKICK - Determines i f the Spin Up Routine will drive the fan to 100% duty cycle for 1/4 of the
programmed spin up time before driving it at the programmed level.
‘0’ (default) - The Spin U p Routine will drive the fan driver to 100% for 1/4 of the prog rammed spin
up time before reverting to the programmed spin level.
‘1’ - The Spin Up Routine will not drive the fan driver to 100%. It will set the drive at the
programmed spin level for the entire duration of the programmed spin up time.
Table 6.32 Gain Decode
GAIND OR GAINP OR GAINI [1:0]
RESPECTIVE GAIN FACTOR10
00 1x
01 2x
1 0 4x (default)
11 8x
Table 6.33 Fan S p in Up Configuration Register
ADDR R/W REGISTER B7 B6 B5 B4 B3 B2 B1 B0 DEFAULT
46h R/W Fan Spin Up
Configuration DRIVE_FAIL
_CNT [1:0] NOK
ICK SPIN_LVL[2:0] SPINUP_TIM
E [1:0] 0Dh
Table 6.34 DRIVE_FAIL_CNT[1:0] Bit Decode
DRIVE_FAIL_CNT[1:0]
NUMBER OF UPDATE PERIODS10
00
Disabled - the Drive Fail detection circuitry is
disabled (default)
01
16 - the Drive Fail detection circuitry will count for 16
update periods
10
32 - the Drive Fail detection circuitry will count for 32
update periods
11
64 - the Drive Fail detection circuitry will count for 64
update periods
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Bits 4 - 2 - SPIN_LVL[2:0] - Determines the final drive level that is used by the Spin Up Routine as
shown in Table 6.35.
Bit 1 -0 - SPINUP_TIME[1:0] - determines the maximum Spin Time that the Spin Up Routine will run
for (see Section 6.9). If a valid tachometer measurement is not detected before the Spin Time has
elapsed, then an interrupt will be generated. When the RPM based Fan Speed Control Algorithm is
active, the fan driver will attempt to re-start the fan immed iatel y af ter the en d of the last spin up attemp t.
The Spin Time is set as shown in Table 6.36.
6.23 Fan Step Register
The Fan Step Register, along with the Update Time, controls the ramp rate of the fan driver response
calculated by the RPM based Fan Speed Control Algorithm. The value of the registers represents the
maximum step size each fan driver will take between update times (see Section 6.19).
Table 6.35 Spin Level
SPIN_LVL[2:0]
SPIN UP DRIVE LEVEL210
0 0 0 30%
0 0 1 35%
0 1 0 40%
0 1 1 45%
1 0 0 50%
1 0 1 55%
1 1 0 60% (default)
1 1 1 65%
Table 6.36 Spin Time
SPINUP_TIME[1:0]
TO TA L SP I N U P TI M E10
0 0 250 ms
0 1 500 ms (default)
1 0 1 sec
1 1 2 sec
Table 6.37 Fan Step Register
ADDR R/W REGISTER B7 B6 B5 B4 B3 B2 B1 B0 DEFAULT
47h R/W Fa n Max Step - - 32 16 8 4 2 1 10h
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When the FSC algorithm is enabled, Ramp Rate control is automatically used. When the FSC is not
active, then Ramp Rate control can be enabled by asserting the EN_RRC bit (see Section 6.20)
APPLICATION NOTE: The UPDATE bits and Fan Step Register settings operate independently of the RPM based
Fan Speed Control Algorithm and will always limit the fan drive setting. That is, if the
programmed fan drive setting (either in determined by the RPM based Fan Speed Control
Algorithm, the Look Up Table, or by manual settings) exceeds the current fan drive setting
by greater than the Fan Step Register setting, the EMC2105 will limit the fan drive change
to the value of the Fan Step Register. It will use the Update Time to determine how often to
update the drive settings.
APPLICATION NOTE: If the Fan Speed Control Algorithm is used, the default settings in the Fan Configuration 2
Register will cause the maximum fan step settings to be ignored.
The Fan Step Registers are software locked.
6.24 Fan Minimum Drive Register
The Fan Minimum Drive Register stores the minimum drive setting for each RPM based Fan Speed
Control Algorith m. The RPM based Fan Speed Co ntrol Algorithm will not drive the fan a t a level lower
than the minimum drive unless the target Fan Speed is set at FFh (see Section 6.27)
During normal operation, if the fan stops for any reason (including low drive), the RPM based Fan
Speed Control Algorithm will attempt to restart the fan. Setting the Fan Minimum Drive Registers to a
setting that will maintain fan operation is a useful way to avoid potential fan oscillations as the control
circuitry attempts to drive it at a level that cannot support fan operation.
The Fan Minimum Drive Register is software locked.
6.25 Valid TACH Count Register
The Valid TACH Count Register stores the maximum TACH Reading Register value to indicate that
the each fan is spinning properly. The value is referenced at the end of the Spin Up Routine to
determine if the fan has started operating and decide if the device needs to retry. See Equation [3] for
translating the count to an RPM. This register is only used when the FSC is active.
If the TACH Reading Register value exceeds the Valid TACH Count Register (indicating that the Fan
RPM is below the threshold set by this count), then a stalled fan is detected. In this condition, the
algorithm will automatically begin its Spin Up Routine.
If a TACH Target setting is set above the Valid TACH Count setting, then that setting will be ignored
and the algorithm will use the current fan drive setting.
Table 6.38 Minimum Fan Drive Register
ADDRR/WREGISTERB7B6B5B4B3B2B1B0DEFAULT
48h R/W Fan Minimum
Drive 128643216 8 4 2 1 66h
(40%)
Table 6.39 Valid TACH Count Register
ADDRR/WREGISTERB7B6B5B4B3B2B1B0DEFAULT
49h R/W Valid T ACH
Count 4096 2048 1024 512 256 128 64 32 F5h
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The Valid TACH Count Register is software locked.
6.26 Fan Drive Fail Band Registers
The Fan Drive Fail Band Registers store the number of tach counts used by the Fan Drive Fail
detection circuitry. This circuitry is activated when the fan drive setting high byte is at FFh. When it is
enabled, the actual measured fan speed is compared against the target fan speed. These registers
are only used when the FSC is active.
This circuitry is used to indicate that the target fan speed at full drive is higher than the fan is actually
capable of reaching. If the measured fan speed does not exceed the target fan speed minus the Fan
Drive Fail Band Register settings for a period of time longer than set by the DRIVE_FAIL_CNTx[1:0]
bits then the DRIVE_FAIL status bit will be set and an interrupt generated.
6.27 TACH Target Registers
The TACH Target Reg isters hold the target tachometer value that is maintained each of the RPM based
Fan Speed Control Algorithms.
The value in the TACH Target Registers will always reflect the current TACH Target value. If the Look
Up Tabl e is active and configured to operate in RPM Mode, then this register will be read only. Writing
to this register will have no affect and the data will not be stored.
If one of the algorithms is enabled then setting the TACH Target Register to FFh will disable the fan
driver (set the fan drive setting to 0%). Setting the TACH Target to any other value (from a setting of
FFh) will cause the algorithm to invoke the Spin Up Routine after which it will function normally.
The Tach Target is not applied until the high byte is written. Once the high byte is written, the current
value of both high and low bytes will be used as the next Tach target. 3
Table 6.40 Fan Drive Fail Band Registers
ADDR R/W REGISTER B7 B6 B5 B4 B3 B2 B1 B0 DEFAULT
4Ah R/W Fan Drive
Fail Band
Low Byte 16 8 4 2 1 - - - 00h
4Bh R/W Fan Drive
Fail Band
High Byte 4096 2048 1024 512 256 128 64 32 00h
Table 6.41 TACH Target Registers
ADDR R/W REGISTER B7 B6 B5 B4 B3 B2 B1 B0 DEFAULT
4Ch R/W TACH T arget
Low Byte 168421- - - F8h
4Dh R/W T ACH Target
High Byte 4096 2048 1024 512 256 128 64 32 FFh
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6.28 TACH Reading Registers
The TACH Reading Registers’ contents describe the current tachometer reading for each of the fan.
By default, the data represents the fan speed as the number of 32kHz clock periods that occur for a
single revolution of the fan.
Equation [3] sho ws the detailed conversion from TACH measurement (COUNT) to RPM while Equation
[4] shows the simplified translation of TACH Reading Register count to RPM assuming a 2-pole fan,
measuring 5 edges, with a frequency of 32.768kHz. T hese equ ations ar e solved and tabulated for ease
of use in AN17.4 RPM to TACH Counts Conversion.
Whenever the high byte register is read, the corresponding low byte data will be loaded to internal
shadow registers so that when the low byte is read, the data will always coincide with the previously
read high byte.
6.29 Look Up Table Configuration Register
The Look Up Table Configuration Register holds the setup information for the two temperature to fan
drive look up tables.
Bit 7 - USE_DTS_F1 - This bit determines whether the Pushed Temperature 1 registers are using
DTS data.
Table 6.42 TACH Reading Registers
ADDR R/W REGISTER B7 B6 B5 B4 B3 B2 B1 B0 DEFAULT
4Eh R Fan TACH 4096 2048 1024 512 256 128 64 32 FFh
4Fh R Fan TACH
Low Byte 168421- - - F8h
where:
[3]
poles = number of poles of the fan
(typically 2)
fTACH = the tachometer
measurement frequency (typically
32.768kHz)
n = number of edges measured
(typically 5 for a 2 pole fan)
m = the multiplier defined by the
RANGe bits [4]
COUNT = TACH Reading Register
value (in decimal)
Table 6.43 Look Up Table Configuration Regi st er
ADDR R/W REGISTER B7 B6 B5 B4 B3 B2 B1 B0 DEFAULT
50h R/W LUT
Configuration USE_D
TS_F1 USE_D
TS_F2 LUT_L
OCK TACH /
DRIVE TEMP3_CFG
[1:0] TEMP4_CFG
[1:0] 00h
RPM 1
poles()
-------------------- n1–()
COUNT 1
m
-----
×
----------------------------------fTACH 60×××=
RPM 3,932,160 m×
COUNT
--------------------------------------
=
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‘0’ (default) - The Pushed Temperature 1 registers are not using DTS data. The contents of these
registers are standard 2’s complement temperature data.
‘1’ - The Pushed Temperature 1 registers are loaded with DTS data. The contents of these
registers are automatically subtracted from a fixed value of 10 0°C be fore they a re compared to the
Look Up Table threshold levels.
Bit 6 - USE_DTS_F2 - This bit determines whether the Pushed Temperature 2 Registers are using
DTS data.
‘0’ (default) - The Pushed Temperature 2 register s are not using DTS data. The contents of these
registers are standard 2’s complement temperature data.
‘1’ - The Pushed Temperature 2 registers are loaded with DTS data. The contents of these registers
are automatically subtracted from a fixed value of 1 00°C before they are compared to the Look Up
Table threshold levels.
Bit 5 - LUT_LOCK - Thi s bit locks upda ting the Look Up Table entri es and determines wheth er the look
up table is being used.
‘0’ (default) - The Look Up Table entries can be updated normally. The Look Up Table will not be
used while the Look Up Table entries are unlocked. During this condition, the fan drive output will
not change states regardless of temperature or tachometer variation.
‘1’ - The Look Up Table entries are locked and cannot be updated. The Look Up Table is fully active
and will be used based on the loaded values. The fan drive output will be updated depending on
the temperature and / or TACH variations.
APPLICATION NOTE: When the LUT_LOCK bit is set at a logic ‘0’, the fan drive setting will be set at whatever
value was last used by the RPM based Fan Speed Control Al gorithm or the Look Up Table.
Bit 4 - TACH / DRIVEx - This bit selects the data format for the LUT drive settings.
‘0’ (default) - The Look Up Table drive settings are RPM TACH count values for use by the RPM
based Fan Speed Control Algorithm. The Look Up Table drive settings should be loaded highest
value to lowest value (to coincide with the inversion between TACH counts and actual RPM).
‘1’ - The Look Up Table drive settings are fan drive setting valu es and are used directly. Th e drive
settings should be loaded lowest value to highest value.
APPLICATION NOTE: The TACH / DRIVE bit should be set prior to the LUT_LOCK bit being set so that, if the fan
driver is disabled, the output drive is in the proper state.
Bits 3-2 - TEMP3_CFG[1:0] - These bits determine the temperature channel that is used for the
Temperature 3 inputs to the Look Up Table as shown in Table 6.44.
Bits 1-0 - TEMP4_CFG[1:0] - These bits determine the temperature channel that is used for the
Temperature 4 inputs to the Look Up Table as shown in Table 6.45.
Table 6.44 TEMP3_CFG Decode
TEMP3_CFG [1:0]
TEMPERATURE CHANNEL USED10
0 0 External Diode 3 (default)
0 1 TRIP_SET / VIN4 Voltage
1 0 Pushed Temperature 1 (LUT)
1 1 Reserved
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APPLICATION NOTE: When any of the External Diode 1, External Diode 2, and External Diode 3 channels are
configured to operate as voltage inputs, the voltage data is used in the Look Up Table instead
of the corresponding temperature data. Therefore, the threshold settings must be updated
accordingly. All voltage channels (including VIN1, VIN2, and VIN3) are assumed to be
increasing (i.e. a larger voltage reading indicates a higher fan speed).
6.30 Look Up Table Registers
Table 6.45 TEMP4_CFG Decode
TEMP4_CFG [1:0]
TEMPERATURE CHANNEL USED10
0 0 Internal Diode (default)
0 1 External Diode 4
1 0 Pushed Temperature 2 (LUT)
11 Reserved
Table 6.46 Look Up Table Registers
ADDR R/W REGISTER TACH /
DRIVEB7B6B5B4B3B2B1B0DEFAULT
51h R/W LUT Drive
Setting 1 ‘0’ 4096 2048 1024 512 256 128 64 32 FBh
‘1’ 128 64 32 16 8 4 2 1
52h R/W
LUT Ext
Diode 1
Setting 1 X - 64 32 16 8 4 2 1 7Fh
(127°C)
LUT VIN1
Setting 1 X 752.9 376.5 188.2 94.12 47.06 23.53 11.76 5.88 7Fh
(0.4V)
53h R/W
LUT Ext
Diode 2
Setting 1 X - 64 32 16 8 4 2 1 7Fh
(127°C)
LUT VIN2
Setting 1 X 752.9 376.5 188.2 94.12 47.06 23.53 11.76 5.88 7Fh
(0.4V)
54h R/W
LUT Temp 3
Setting 1 X - 64 32 16 8 4 2 1 7Fh
(127°C)
LUT Voltage
3 Setting 1 X 752.9 376.5 188.2 94.12 47.06 23.53 11.76 5.88 7Fh
(0.4V)
55h R/W LUT Temp 4
Setting 1 X - 64 32 16 8 4 2 1 7Fh
(127°C)
... ... ... ... ... ... ... ... ... ... ... ... .. .
74h R/W LUT Drive
Setting 8 ‘0’ 4096 2048 1024 512 256 128 64 32 92h
‘1’ 128 64 32 16 8 4 2 1
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The Look Up Table Registers hold the 40 entries of the Look Up Table that controls the drive of the
Fan. As the temperature (or voltage) channels are updated, the measured value for each channel is
compared against the respective entries in the Look Up Table and the associated drive setting is
loaded into an internal shadow register and stored.
The bit weighting for temperature inputs represents °C and is compared against the measured data.
Note that the LUT entry does not include a sign bit. The Look Up Table does not support negative
temperature values and the MSBit should not be set for a temperature input.
The bit weighting for voltage inputs represents mV above 0V and is compared against the measured
data.
Each temperature (or voltage) channel threshold shares the same hysteresis value. When the
measured temperature for any of the channels meets or exceeds the programmed thresh old, the drive
setting associated with that threshold is used. The temperature must drop below the threshold minus
the hysteresis value before the drive setting will be set to the previous value.
APPLICATION NOTE: For proper operation, the hysteresis must be smaller than the difference between two
consecutive thresholds.
If the RPM based Fan Speed Control Algorithm is used, the TACH Target is updated after every
conversion. It is always set to the minimum TACH Target th at is stored by the Look Up Table. The fan
drive setting cycle is updated based on the RPM based Fan Speed Control Algorithm configuration
settings.
If the RPM based Fan Speed Control Algorithm is no t used, then the fan drive setting is updated after
every conversion. It is set to the maximum duty cycle that is stored by the Look Up Table.
75h R/W
LUT Ext
Diode 1
Setting 8 X - 64 32 16 8 4 2 1 7Fh
(127°C)
LUT VIN1
Setting 8 X 752.9 376.5 188.2 94.12 47.06 23.53 11.76 5.88 7Fh
(0.4V)
76h R/W
LUT Ext
Diode 2
Setting 8 X - 64 32 16 8 4 2 1 7Fh
(127°C)
LUT VIN2
Setting 8 X 752.9 376.5 188.2 94.12 47.06 23.53 11.76 5.88 7Fh
(0.4V)
77h R/W
LUT Temp 3
Setting 8 X - 64 32 16 8 4 2 1 7Fh
(127°C)
LUT Voltage
3 Setting 8 X 752.9 376.5 188.2 94.12 47.06 23.53 11.76 5.88 7Fh
(0.4V)
78h R/W LUT Temp 4
Setting 8 X - 64 32 16 8 4 2 1 7Fh
(127°C)
79h R/W LUT Temp
Hysteresis X - - -168421 0Ah
Table 6.46 Look Up Table Registers (continued)
ADDR R/W REGISTER TACH /
DRIVEB7B6B5B4B3B2B1B0DEFAULT
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6.31 Muxed Pin Configuration Register
The Muxed Pin Configuration Register controls the pin function for the multiple function GPIO pin.
Bit 0 - GPIO1_CFG - Determines the pin function for the CLK_IN / GPIO1 pin.
‘0’ - The CLK_IN / GPIO1 pin functions as a clock input for the RPM based Fan Speed Control
Algorithm (FSC).
‘1’ (default) - The CLK_IN / GPIO1 pin functions as a GPIO.
6.32 GPIO Direction Register
The GPIO Direction Register 1 controls the direction of GPIOs 1 through 6. When muxable pins are
not configured as a GPIO ports the respective bits are ignored.
Bit 5 - 0 - GPIOx_DIR - Controls the input / output state of GPIOs. The bit is not used if the pin is not
configured as a GPIO.
‘0’ (default) - The GPIO is configured as an input.
‘1’ - The GPIO is configured as an output.
6.33 GPIO Pin Output Configuration Register
The GPIO Output Configuration Register controls the output pin type of the GPIO pin. Bit 0 -
GPIO1_OT - Determines the output type for GPIOx.
‘0’ (default) - GPIO1 is configured as an open drain output (if enabled as an output).
‘1’ - GPIO1is configured as a push-pull output (if enabled as an output).
Table 6.47 Muxed Pin Configuration Register
ADDR R/W REGISTER B7 B6 B5 B4 B3 B2 B1 B0 DEFAULT
E0h R/W Muxed Pin
Config --- ----
GPIO1
_CFG 01h
Table 6.48 GPIO Direction Register
ADDRR/WREGISTERB7B6B5B4B3B2B1B0DEFAULT
E1h R/W GPIO
Direction 1 -------
GPIO
1_DIR 00h
Table 6.49 GPIO Pin Output Configuration Register
ADDR R/W REGISTER B7 B6 B5 B4 B3 B2 B1 B0 DEFAULT
E2 R/W GPIO
Output
Config -------
GPIO
1_OT 00h
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6.34 GPIO Input Register
The GPIO Input Register indicates the state of the GPIO pin regardless of the direction of the GPIO
(input, push-pull output, open-drain output). When the GPIO is configured as an input, any change of
state will assert the ALERT# pin (unless GPIO interrupts are masked, see Section 6.15).
6.35 GPIO Output Register
The GPIO Output Register controls the state of theGPIO pin when it is configured as an output.
If the output is configured as an open-drain output, then it requires a pull-up resistor to VDD. Setting
the corresponding bit to a ‘ 1’ will act to disab le the output allowing the pu ll-up resistor to pull the output
high. Setting the correspondin g bit to a ‘0’ will enable the output and drive the pin to a logical ‘0’ state.
If the output is configured as a push-pull output, then output pin will immediately be driven to match
the corresponding bit setting.
6.36 GPIO Interrupt Enable Register
The GPIO Interrupt Enable Register enables the GP IO to assert the ALERT pin when it changes state.
When the GPIO pin is disabled or configured as an output, then this bit is ignored.
Bit 0 - GPIO1_INT_EN - Allows the ALERT# pin to be asserted when the GPIO1 pin changes state
(when configured as an input).
‘0’ (default) - The ALERT# pin will not be asserted when the GPIO1 pin changes state (when
configured as an input).
‘1’ - The ALERT# pin will be asserted when the GPIO1pin changes state (when configured as an
input).
Table 6.50 GPIO Input Register
ADDR R/W REGISTER B7 B6 B5 B4 B3 B2 B1 B0 DEFAULT
E3hRGPIO Input ---- ---
GPIO
1_IN 00h
Table 6.51 GPIO Output Register
ADDR R/W REGISTER B7 B6 B5 B4 B3 B2 B1 B0 DEFAULT
E4h R/W GPIO
Output 1 -------
GPIO1
_OUT 00h
Table 6.52 GPIO Interrupt Ena ble Register
ADDR R/W REGISTER B7 B6 B5 B4 B3 B2 B1 B0 DEFAULT
E5h R/W GPIO
Interrupt
Enable -------
GPIO1_
INT_EN 00h
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6.37 GPIO Status Register
The GPIO Status Register indicates which GPIO has changed states to cause the ALERT pins to be
asserted. This register is cleared when it is read. The bits in this register are set whenever the
corresponding GPIO changes states regardless if the ALERT pins are asserted. Once a bit is set, it
will remain set until read.
If any bit in this register is set, then the GPIO status bit will be set.
Bit 0 - GPIO1_STS - Indicates that the GPIO1 pin has changed states from a ‘0’ to a ‘1’ or a ‘1’ to a
‘0’ (when configured as a GPIO input).
6.38 Software Lock Register
The Software Lock Register controls the software locking of critical registers. This register is software
locked.
Bit 0 - LOCK - this bit acts on all registers that are designated SWL. When this bit is set, the locked
registers become read only and cannot be updated.
‘0’ (default) - all SWL registers can be updated normally.
‘1’ - all SWL registers cannot be updated and a hard-reset is required to unlock them.
6.39 Product Features Register
The Product Features Register indicates which pin selected functionality is enabled.
Bit 1 - 0 - SHDN_SEL[1:0] - Ind icates wh at the d etected p in state of the SHDN _SEL p in was an d which
functions are enabled.
Table 6.53 GPIO Status Register
ADDR R/W REGISTER B7 B6 B5 B4 B3 B2 B1 B0 DEFAULT
E6h R-C GPIO
Status -------
GPIO1_
STS 00h
Tab le 6.54 Software Lock Register
ADDR R/W REGISTER B7 B6 B5 B4 B3 B2 B1 B0 DEFAULT
EFh R/W Software
Lock - - - - - - - LOCK 00h
Table 6.55 Product Features Register
ADDR R/W REGISTER B7 B6 B5 B4 B3 B2 B1 B0 DEFAULT
FCh R Product
Features - - - - - - SHDN_SEL[1:0] 00h
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6.40 Product ID Register
The Product ID Register contains a unique 8 bit word that identifies the product.
6.41 Manufacturer ID Register
The Manufacturer ID Register contains a 8 bit word that identifies SMSC.
6.42 Revision Register
The Revision Register contains a 8 bit word that identifies the die revision.
Table 6.56 SHDN_SEL Bit Decode
FUN_SEL[1:0]
EXTERNAL DIODE 1 MODE
CRITICAL / THERMAL
SHUTDOWN
TEMPERATURE RANGE VIN4 OR
TRIP_SET10
00
Transistor mode - Beta =
automatic
REC = enabled High range - 92°C to 154°C TRIP_SET
01 Diode mode -
B e ta = 1111 b
REC = disabled Low Range
60°C to 122°C TRIP_SET
10 Not used -
Internal diode linked to
Hardware Thermal / Critical
Shutdown circuitry
Low Range
60°C to 122°C TRIP_SET or VIN4
(see Section 6.1.2)
Table 6.57 Product ID Register
ADDR R/W REGISTER B7 B6 B5 B4 B3 B2 B1 B0 DEFAULT
FDh R Product ID
Register 00 0 1 1 0 1 1 1Bh
Table 6.58 Manufacturer ID Reg iste r
ADDR R/W REGISTER B7 B6 B5 B4 B3 B2 B1 B0 DEFAULT
FEh R Manufacturer ID 0 1 0 1 1 1 0 1 5Dh
Table 6.59 Revision Register
ADDR R/W REGISTER B7 B6 B5 B4 B3 B2 B1 B0 DEFAULT
FFh R Revision 0 0 0 0 0 0 1 0 02h
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Chapter 7 Package Drawing
7.1 QFN 20-Pin 4mm x 4mm
Figure 7.1 EMC2105 20-Pin 4x4mm QFN Package Outline and Parameters
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7.2 Package Markings
All devices will be marked on the first line of the top side with “2105”. On the second line, they will be
marked the Lot Number, and on the third line, they will be marked with the Functional Revision “C”
and Country Code.
Figure 7.2 EMC2105 Package Markings
BOTTOM
BOTTOM MARKING NOT ALLOWED
LINE: 1 – SMS C Logo without circled (R) symbol
LINE: 2 – Device Number
LINE: 3 – Last 7 digits of Lot Number
LINE: 4 – Revision and Country Code (RCC )
LINES 1 to 3: CENTER HORIZONTAL ALIGNMENT
LINE 4: LEFT HOR IZONTAL ALIGNM EN T
PB-FREE/GREEN SYMBOL
(M atte Sn)
0.41
3x 0.56
TOP
e3
PIN 1
2105
CCR
123456a
-1
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Appendix A Thermistors
The EMC2105 can monitor thermistor inputs on the TRIP_SET / VIN4 as well as supporting a
thermistor option on the all of the external diode pins pairs (DP1 / VREF_T1 and DN1 / VIN1,etc.).
The Thermistors can be connected as shown in Figure A.1.
Figure A.1 is representative of one of the thermistor channels and will apply to DP1 / VREF_T1 and
DN1 / VIN1, DP2 / VREF_T2 and DN2 / VIN2.
The top side resistor is internally integrated in t he case of the TR IP_SET / VIN4 chann el and the VREF
voltage will not be brought out externally. The Thermistor should be connected in the same way as
RSET.
The relationship between voltage and temperature is roughly linear. the measured voltage by the
EMC2105 will be inversely proportional to temperature .
Linearization methods can only accurately capture the temperature over a limited window of
temperatures.
For a 10k Ohm type 3370 Thermistor and a 1.2k ohm ±1% setting resistor, the output response
corresponding to a thermistor is tabulated in Table A.1.
If the INV_VINx bit is set then the results of the circuit (configured as shown in Figure A.1) is shown
in Table A.2.
The EMC2105 does not perform any numerical calculations on the thermistor value if a thermistor is
monitored on TRIP_SET / VIN4 pin. If the External Diode 1, External Diode 2, or External Diode 3
channels are configured to measure a thermistor, it must be configured as shown in Figure A.1.
When measuring a thermistor input with Fan Control Look Up Table, care must be taken that the
temperature thresholds are entered as a unsigned voltage number that corresponds to the desired
thermal threshold. Also note that the LUT assumes that the VIN1 and TRIP_SET / VIN4 voltage inputs
are directly proportional to temperature.
Figure A.1 “Low Side” Thermistor Connection
10K 1%
Thermistor
DP3 / DN4 / VREF_T3
DN3 / DP4 / VIN3
1.2K
1%
0.1uF
EMC2104/5/6
ADC
Buffer Reference
Voltage
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A.1 Thermistor Look Up Tables
Table A.1 “Low Side” Thermistor Look Up Table
T
(°C) ADC
CODE T
(°C) ADC
CODE T
(°C) ADC
CODE T
(°C) ADC
CODE
-45 254 15 235 75 157 135 72
-44 253 16 235 76 155 136 71
-43 253 17 234 77 154 137 70
-42 253 18 233 78 152 138 69
-41 253 19 232 79 150 139 68
-40 253 20 231 80 148 140 67
-39 253 21 231 81 146 141 66
-38 253 22 230 82 145 142 65
-37 252 23 229 83 143 143 64
-36 252 24 228 84 141 144 63
-35 252 25 227 85 139 145 62
-34 252 26 226 86 138 146 61
-33 252 27 225 87 136 147 60
-32 252 28 224 88 135 148 59
-31 252 29 223 89 133 149 59
-30 252 30 222 90 131 150 58
-29 251 31 221 91 129 151 57
-28 251 32 220 92 128 152 56
-27 251 33 219 93 126 153 55
-26 251 34 218 94 124 154 54
-25 251 35 217 95 123 155 54
-24 251 36 216 96 121 156 53
-23 250 37 215 97 119 157 52
-22 250 38 213 98 118 158 51
-21 250 39 212 99 116 159 51
-20 250 40 211 100 114 160 50
-19 250 41 210 101 113 161 49
-18 249 42 208 102 111 162 48
-17 249 43 207 103 110 163 48
-16 249 44 206 104 108 164 47
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-15 249 45 205 105 106 165 46
-14 248 46 203 106 105 166 46
-13 248 47 202 107 103 167 45
-12 248 48 200 108 102 168 44
-11 247 49 199 109 100 169 44
-10 247 50 198 110 99 170 43
-9 247 51 196 111 97 171 43
-8 246 52 195 112 96 172 42
-7 246 53 193 113 95 173 41
-6 246 54 192 114 93 174 41
-5 245 55 190 115 92 175 40
-4 245 56 189 116 90 176 40
-3 245 57 187 117 89 177 39
-2 244 58 185 118 88 178 38
-1 244 59 184 119 86 179 38
0 243 60 182 120 85 180 37
1 243 61 181 121 84 181 37
2 243 62 179 122 82 182 36
3 242 63 177 123 81 183 36
4 242 64 176 124 80 184 35
5 241 65 174 125 79 185 35
6 241 66 172 126 82 186 34
7 240 67 171 127 81 187 34
8 240 68 169 128 80 188 33
9 239 69 167 129 78 189 33
10 238 70 166 130 77 190 32
11 238 71 164 131 76 191 32
12 237 72 162 132 75
13 237 73 160 133 74
14 236 74 159 134 73
Table A.1 “Low Side” Thermistor Look Up Table (continued)
T
(°C) ADC
CODE T
(°C) ADC
CODE T
(°C) ADC
CODE T
(°C) ADC
CODE
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Table A.2 Inverted Thermisto r Look Up Table
T
(°C) ADC
CODE T
(°C) ADC
CODE T
(°C) ADC
CODE T
(°C) ADC
CODE
-45 0 15 19 75 97 135 182
-44 1 16 20 76 99 136 183
-43 1 17 20 77 100 137 184
-42 1 18 21 78 102 138 185
-41 1 19 22 79 104 139 186
-40 1 20 23 80 106 140 187
-39 1 21 23 81 108 141 188
-38 1 22 24 82 109 142 189
-37 2 23 25 83 111 143 190
-36 2 24 26 84 113 144 191
-35 2 25 27 85 115 145 192
-34 2 26 28 86 116 146 193
-33 2 27 29 87 118 147 194
-32 2 28 30 88 120 148 195
-31 2 29 31 89 121 149 195
-30 2 30 32 90 123 150 196
-29 3 31 33 91 125 151 197
-28 3 32 34 92 126 152 198
-27 3 33 35 93 128 153 199
-26 3 34 36 94 130 154 200
-25 3 35 37 95 131 155 200
-24 3 36 38 96 133 156 201
-23 4 37 39 97 135 157 202
-22 4 38 41 98 136 158 203
-21 4 39 42 99 138 159 203
-20 4 40 43 100 140 160 204
-19 4 41 44 101 141 161 205
-18 5 42 46 102 143 162 206
-17 5 43 47 103 144 163 206
-16 5 44 48 104 146 164 207
-15 5 45 50 105 148 165 208
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-14 6 46 51 106 149 166 208
-13 6 47 52 107 151 167 209
-12 6 48 54 108 152 168 210
-11 7 49 55 109 154 169 210
-10 7 50 56 110 155 170 211
-9 7 51 58 111 157 171 211
-8 8 52 59 112 158 172 212
-7 8 53 61 113 159 173 213
-6 8 54 62 114 161 174 213
-5 9 55 64 115 162 175 214
-4 9 56 65 116 164 176 214
-3 9 57 67 117 165 177 215
-2 10 58 69 118 166 178 216
-1 10 59 70 119 168 179 216
0 11 60 72 120 169 180 217
1 11 61 73 121 170 181 217
2 11 62 75 122 172 182 218
3 12 63 77 123 173 183 218
4 12 64 78 124 174 184 219
5 13 65 80 125 175 185 219
6 13 66 82 126 172 186 220
7 14 67 83 127 173 187 220
8 15 68 85 128 174 188 221
9 15 69 87 129 176 189 221
10 16 70 88 130 177 190 222
11 16 71 90 131 178 191 222
12 17 72 92 132 179
13 18 73 94 133 180
14 18 74 95 134 181
Table A.2 Inverted Thermisto r Lo ok Up Table (continued)
T
(°C) ADC
CODE T
(°C) ADC
CODE T
(°C) ADC
CODE T
(°C) ADC
CODE
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Appendix B Look Up Table Operation
The EMC2105 uses a look-up table to apply a user-programmable fan control profile based on
measured temperature to the fan driver. In this look-up table, each temperature channel is allowed to
control the fan drive output independently (or jointly) by programming up to eight pairs of temperature
and drive setting entries.
The user programs the look-up table based on the desired operation. If the RPM based Fan Speed
Control Algorithm is to be used (see Section 6.6), then th e user must program an RPM target for each
temperature setting of interest. Altern ately, if the RPM based Fan Speed Control Algorithm is not to be
used, then the user must program a drive setting for each temperature setting of interest.
If the measured temperature on the External Diode channel meets or exceeds any of the temperature
thresholds for any of the channels, the fan output will be automatically set to the desired setting
corresponding to the exceeded temperature. In cases where multiple temperature channel thresholds
are exceeded, the highest fan drive setting will take precedence.
When the measured temperat ure drops to a point below a lower threshold minus the hysteresis value,
the fan output will be set to the corresponding lower set point.
The following sections show examples of how the Look Up Table is used and configured. Each Look
Up Table Example uses the Fan 1 Look Up Table Registers configured as shown in Table B.1.
B.1 Example #1
This example does not use the RPM based Fan Speed Control Algorithm. Instead, the Look Up Table
is configured to directly set a fan drive setting bas ed on the temperature of f our of its measured inputs.
The configuration is set as shown in Table B.2.
Once configured, the Look Up Table is loaded as shown in Table B.3. Table B.3 shows three
temperature configurations using the settings in Table B.3 and the final fan drive setting that the Look
Up Table will select.
Table B.1 Look Up Table Format
STEP TEMP 1 TEMP 2 TEMP 3 TEMP 4 LUT DRIVE
1LUT Temp 1
Setting 1 (52h) LUT Temp 2
Setting 1 (53h) LUT Temp 3
Setting 1 (54h) LUT Temp 4
Setting 1 (55h) LUT Drive
Setting 1 (51h)
2LUT Temp 1
Setting 2 (57h) LUT Temp 2
Setting 2 (58h) LUT Temp 3
Setting 2 (59h) LUT Temp 4
Setting 2 (5Ah) LUT Drive
Setting 2 (56h)
3LUT Temp 1
Setting 3 (5Ch) LUT Temp 2
Setting 3 (5Dh) LUT Temp 3
Setting 3 (5Eh) LUT Temp 4
Setting 3 (5Fh) LUT Drive
Setting 3 (5Bh)
4LUT Temp 1
Setting 4 (61h) LUT Temp 2
Setting 4 (62h) LUT Temp 3
Setting 4 (63h) LUT Temp 4
Setting 4 (64h) LUT Drive
Setting 4 (60h)
5LUT Temp 1
Setting 5 (66h) LUT Temp 2
Setting 5 (67h) LUT Temp 3
Setting 5 (68h) LUT Temp 4
Setting 5 (69h) LUT Drive
Setting 5 (65h)
6LUT Temp 1
Setting 6 (6Bh) LUT Temp 2
Setting 6 (6Ch) LUT Temp 3
Setting 6 (6Dh) LUT Temp 4
Setting 6 (6Eh) LUT Drive
Setting 6 (6Ah)
7LUT Temp 1
Setting 7 (70h) LUT Temp 2
Setting 7 (71h) LUT Temp 3
Setting 7 (72h) LUT Temp 4
Setting 7 (73h) LUT Drive
Setting 7 (6Fh)
8LUT Temp 1
Setting 8 (75h) LUT Temp 2
Setting 8 (76h) LUT Temp 3
Setting 8 (77h) LUT Temp 4
Setting 8 (78h) LUT Drive
Setting 8 (74h)
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B.1.1 LUT Configuration Bit Description
Bit 7 - USE_DTS_F1 = ‘0b’ tells the circuitry that the Forced Temperature 1 registe r data is not in DTS
format.
Bit 6 - USE_DTS_F2 = ‘0b’ tells the circuitry that the Forced Temperature 2 registe r data is not in DTS
format.
Bit 5 - LUT_LOCK = ‘1b’ tells the circuitry that the LUT is programmed and is active. This bit must be
set for the LUT to function.
Bit 4 - TACH / DRIVE = ‘1b’ tells the Look Up Table that the FSC algorithm is not used and that the
LUT target values will be PWM drive settings instead of TACH Target settings.
Bits 3- 2 - TEMP3_CFG = ‘00b’ tells the LUT to re ference the External Diode 3 data instead of Forced
Temperature 1 data or the TRIP_SET / VIN4 voltage data. This is the default setting.
Bit 0 - TEMP4_CFG = ‘0b’ tells the LUT to reference the Internal Diode data instead of Forced
Temperature 2 data or the External Diode 4 temperature data. This is the default setting.
Note: The values shown in Table B.3 are example settings. All the cells in the look-up table are
programmable via SMBus.
Table B.2 Look Up Table Example # 1 Co nfiguration
ADDR REGISTER B7 B6 B5 B4 B3 B2 B1 B0 SETTING
50h LUT 1
Configuration
USE_D
TS_F1 USE_D
TS_F2 LUT_L
OCK T ACH /
DRIVE TEMP3_CFG
[1:0] TEMP4_CFG
[1:0] C0h
0 01100 00
Table B.3 Fan Speed Control Table Example #1
FAN
SPEED
STEP #
EXTERNAL
DIODE 1
TEMPERATURE
(CPU)
EXTERNAL
DIODE 2
TEMPERATURE
(GPU)
EXTERNAL
DIODE 3
TEMPERATURE
(SKIN)
INTERNAL DIODE
TEMPERATURE
(AMBIENT) FAN DRIVE
SETTINGS
135
oC60
oC30
oC40
oC0%
240
oC70
oC35
oC45
oC30%
350
oC75
oC40
oC50
oC40%
460
oC80
oC45
oC55
oC50%
570
oC85
oC50
oC60
oC60%
680
oC90
oC55
oC65
oC70%
790
oC95
oC60
oC70
oC80%
8100
oC100
oC65
oC75
oC 100%
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B.2 Example #2
This example uses the RPM based Fan Speed Control Algorithm. The Spin Level (used by the Spin
Up Routine) should be changed to 50% drive for a total Spin Time of 1 second. For all other RPM
configuration settings, the default conditions are used.
For control inputs, it uses the External Diode 1 channel normally, a thermistor input on the External
Diode 2 channel, the internal diode channel, and a Pushed Temperature that represents the MCU
temperature in standard format. The configuration is set as shown in Table B.5 while Table B.6 shows
how the table is loaded.
Note that when using Thermistor data, the VIN2_INV bit should be set. The circuitry will automatically
subtract the measured thermistor vo ltage from a quantity of FFh (effectively inverting it). Th erefore, the
Look Up Table is loaded with ascending voltage thresholds with respect to the drive settings.
Additionally, the reading register will show this same value (subtracted from FFh).
Tab le B.4 Fan Speed Determination for Example #1 (using settings in Table B.3)
EXTERNAL
DIODE 1
TEMPERATURE
(CPU)
EXTERNAL
DIODE 2
TEMPERATURE
(GPU)
EXTERNAL DIODE
3 TEMPERATURE
(SKIN)
INTERNAL DIODE
TEMPERATURE
(AMBIENT) FAN DRIVE
SETTING RESULT
Example 1: 82°C 82°C 48°C 58°C 70% (CPU temp
requires highe st drive)
Example 2: 82C° 97°C 62°C 58°C 80% (GPU and Skin
require highest drive)
Example 3: 82°C 97°C 62°C 75°C 100% (Internal temp
requires highe st drive)
Table B.5 Look Up Table Example # 2 Co nfiguration
ADDR REGISTER B7 B6 B5 B4 B3 B2 B1 B0 SETTING
22h Configuration
3-VIN4_I
NV VIN3_E
NVIN3_I
NV VIN2_
EN VIN2_I
NV VIN1_
EN VIN1_I
NV 0Ch
- 0 0 0 1100
42h Fan 1
Configuration
1
EN_
ALGO RANGE[1:0] EDGES[1:0] UPDATE[2:0] ABh
10101011
46h Fan 1 Spin
Up
Configuration
DRIVE_FAIL_CNT
1 [1:0] NOKICK
1SPIN_LVL[2:0] SPINUP_TIME
[1:0] 0Ah
00001010
50h LUT 1
Configuration
USE_D
TS_F1 USE_D
TS_F2 LUT_LO
CK TACH /
DRIVE TEMP3_CFG
[1:0] TEMP4_CFG
[1:0] 28h
00101000
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B.2.1 Configuration 3 Bit Description
Bit 6 - VIN4_INV = ‘0b’ tells the circuitry that the VIN4 voltage is not inverted and will be asscending
(i.e. a value of 7Fh will represent a larger value than a value of 30h) If used by the LUT, no special
processing needs to be done. This is the default setting.
Bit 5 - VIN3_EN = ‘0b’ tells the circuitry that the VIN3 voltage is not measured. The External Diode 3
pins will measure the External Diode 3 temperature. This is the default setting.
Bit 4 - VIN3_INV = ‘0b’ tells the circuitry that the VIN3 voltage is not inverted. This bit is ignored
because VIN3_EN = ‘0b’. This is the default setting
Bit 3 - VIN2_EN = ‘1b’ tells the circuitry that the External Diode 2 pins (DP2 and DN2) will measure
the VIN2 voltage and will not measure the External Diod e 2 temperature. Th is voltage will au to ma tica lly
be used by the LUT.
Bit 2 - VIN2_INV = ‘1b’ tells the circuitry that the VIN2 voltage should be inverted. This means that
prior to any limit comparasions (via the high / low limits or the LUT), the measured value will be
subtracted from a value of FFh.
Bit 1 - VIN1_EN = ‘0b’ tells the circuitry that the VIN1 voltage is not measrued. The External Diode 1
pins (DP1 and DN1) will measure the External Diode 1 temperatu re and will be used by the LUT. This
is the default setting.
Bit 0 - VIN1_INV = ‘0b’ tells the circuitry that the VIN1 voltage is not inverted. This bit is ignored
because VIN1_EN = ‘0b’. This is the defautl setting.
B.2.2 Fan Configuration 1 Bit Description
Bit 7 - EN-ALGO = ‘1b’ tells the circuitry that the FSC alogrithm is active.
Bits 6 - 5 - RANGE[1:0] = ‘01b’ tells the FSC that the expected minimum RPM is 1000. This is the
defautl setting.
Bits 4-3 - EDGES[1:0] = ‘01b’ tells the FSC that the fan is a 2-pole fan generating tach edges per
rotation. This is the defautl setting.
Bits 2 - 0 - UPDATE[2:0] = ‘011b’ tells the FSC to update th e fan drive every 400ms. This is the default
setting.
B.2.3 Fan Spin Up Configuration Bit Description
Bits 7-6 - DRIVE_FAIL_CNT[1:0] = ‘00b’ tells the circuitry that the drive fail detection circuitry is not
enabled. This is the default setting.
Bit 5 - NOKICK = ‘0b’ tells the circuitry that if than Spin Up Routine is invoked, it will drive to 100%
duty cycle for 25% of the spin up time. This is the default setting.
Bits 4-2 - SPIN_LVL[2:0] = ‘010b’ tells the circuitry that if the Spin Up Routine is invoked, it sho uld run
at 40% drive.
Bits 1-0 - SPINUP_TIME[1:0] = ‘10b’ tells the circuitry that if the Spin Up Routine is invoked, it will run
at 100% duty cycle for 250ms and at 40% duty cycle for 750ms for a total spin up time of 1s.
B.2.4 LUT Configuration - Bit Description
7 - USE_DTS_F1 = ‘0b’ tells the circuitry that the data in the Pushed Temperature 1 register is in
normal format.
Bit 6 - USE_DTS_F2 = ‘0b’ tells the circuitry that the data in the Pushed Temperature 2 register is in
normal format.
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Bit 5 - LUT_LOCK = ‘1b’ tells the circuitry that the LUT is programmed and is active. This bit must be
set for the LUT to function.
Bit 4 -TACH / DRIVE = ‘0b’ tells the LUT circuitry that the FSC algorithm is active and that the LUT
values are TACH Target settings. This is the default setting.
Bits 3-2 - TEMP3_CFG = ‘10’b tells the Look Up Table to reference the Forced Temperature 1 data
instead of the External Diode 3 data or the TRIP_SET / VIN4 data.
Bits 1- 0- TEMP4_CFG = ‘00b’ tells the Look Up Table to reference the Internal Temperature data
instead of the External Diode 4 data or the Forced Temperature 2 data.
Note: The values shown in Table B.6 are example settings. All the cells in the look-up table are
programmable via SMBus.
Table B.6 Fan Speed Control Table Example #2
FAN
SPEED
STEP #
EXTERNAL DIODE
1 TE MPERATURE
(CPU)
THERMISTOR 2
VOLTAGE
READING
PUSHED
TEMPERATURE
SETTING
INTERNAL DIODE
TEMPERATURE
(AMBIENT) TACH
TARGET
135
oC156.25mV
(45°C) 30oC40
oCEFh
(1028 RPM)
240
oC178.125mV
(50°C) 35oC45
oCA3h
(1508 RPM)
350
oC203.125mV
(55°C) 40oC50
oC7Ah
(2014 RPM)
460
oC 228.125mV
(60°C) 45oC55
oC62h
(2508 RPM)
570
oC253.125mV
(65°C) 50oC60
oC52h
(2997 RPM)
680
oC278.125mV
(70°C) 55oC65
oC3Dh
(4029 RPM)
790
oC306.25mV
(75°C) 60oC70
oC31h
(5016 RPM)
8100
oC334.375mV
(80°C) 65oC75
oC29h
(5994 RPM)
Tab le B.7 Fan Speed Determination for Example #2 (using settings in Table B.6)
EXTERNAL
DIODE 1
TEMPERATURE
(CPU)
THERMISTOR 2
VOLTAGE
READING PUSHED
TEMPERATURE
INTERNAL DIODE
TEMPERATURE
(AMBIENT) FAN DRIVE
SETTING RESULT
Example 1: 75°C 140.375mV 48°C 58°C 52h (2997 RPM) -
CPU requires highest
target
Example 2: 75°C 310mV 58°C 58°C 31h (5016 RPM)
Thermistor requires
highest target
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B.3 Example #3
This example uses the RPM based Fan Speed Control Algorithm. The Spin Level (used by the Spin
Up Routine) should be changed to 50% drive for a total Spin Time of 1 second. For all other RPM
configuration settings, the default conditions are used.
For control inputs, it uses the External Diode 1 channel normally, the External Diode 2 channel
normally, and both Pushed Temperature registers in DTS format. The configuration is set as shown in
Table B.8 while Table B.9 shows how the table is loaded.
Note that when using DTS data, the USE_DTS_F1 and / or USE_DTS_F2 bits should be set. The
Pushed Temperature Registers are loaded with the normal DTS values as received by the processor.
When the DTS value is used by the Loo k Up Table, the value that is stored in the Pushed Temp erature
Register is subtracted from a fixed temperature of 100°C.
This resultant value is then compared against the Look Up Table thresholds normally. When
programming the Look Up Table, it is necessary to take this translation into account else incorrect
settings may be selected.
B.3.1 Fan Configuration 1 Bit Description
Bit 7 - EN-ALGO = ‘1b’ tells the circuitry that the FSC alogrithm is active.
Bits 6 - 5 - RANGE[1:0] = ‘01b’ tells the FSC that the expected minimum RPM is 1000. This is the
defautl setting.
Bits 4-3 - EDGES[1:0] = ‘01b’ tells the FSC that the fan is a 2-pole fan generating tach edges per
rotation. This is the defautl setting.
Example 3: 75°C 235.125mV 62°C 58°C 31h (5016 RPM)
Pushed Temperature
requires highest
target
Table B.8 Look Up Table Example # 3 Co nfiguration
ADDR REGISTER B7 B6 B5 B4 B3 B2 B1 B0 SETTING
42h Fan 1
Configuration
1
EN_
ALGO RANGE[1:0] EDGES[1:0] UPDATE[2:0] ABh
10101011
46h Fan 1 Spin
Up
Configuration
DRIVE_FAIL_CNT
1 [1:0] NOKICK
1SPIN_LVL[2:0] SPINUP_TIME
[1:0] 0Ah
00001010
50h LUT 1
Configuration
USE_D
TS_F1 USE_D
TS_F2 LUT_LO
CK TACH /
DRIVE TEMP3_CFG
[1:0] TEMP4_CFG
[1:0] EAh
11101010
Tab le B.7 Fan Speed Determination for Example #2 (using settings in Table B.6)
EXTERNAL
DIODE 1
TEMPERATURE
(CPU)
THERMISTOR 2
VOLTAGE
READING PUSHED
TEMPERATURE
INTERNAL DIODE
TEMPERATURE
(AMBIENT) FAN DRIVE
SETTING RESULT
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Bits 2 - 0 - UPDATE[2:0] = ‘011b’ tells the FSC to update th e fan drive every 400ms. This is the default
setting.
B.3.2 Fan Spin Up Configuration Bit Description
Bits 7-6 - DRIVE_FAIL_CNT[1:0] = ‘00b’ tells the circuitry that the drive fail detection circuitry is not
enabled. This is the default setting.
Bit 5 - NOKICK = ‘0b’ tells the circuitry that if than Spin Up Routine is invoked, it will drive to 100%
duty cycle for 25% of the spin up time. This is the default setting.
Bits 4-2 - SPIN_LVL[2:0] = ‘010b’ tells the circuitry that if the Spin Up Routine is invoked, it sho uld run
at 40% drive.
Bits 1-0 - SPINUP_TIME[1:0] = ‘10b’ tells the circuitry that if the Spin Up Routine is invoked, it will run
at 100% duty cycle for 250ms and at 40% duty cycle for 750ms for a total spin up time of 1s.
B.3.3 LUT Configuration - Bit Description
Bit 7 - USE_DTS_F1 = ‘1b’ tells the circuitry that the data in the Pushed Temperature 1 register is in
DTS format which means that the value in the register is equal to 100C - CPU Temp.
Bit 6 - USE_DTS_F2 = ‘1b’ tells the circuitry that the data in the Pushed Temperature 2 register is in
DTS format which means that the value in the register is equal to 100°C - CPU temp.
Bit 5 - LUT_LOCK = ‘1b’ tells the circuitry that the LUT is programmed and is active. This bit must be
set for the LUT to function.
Bit 4 -TACH / DRIVE = ‘0b’ tells the LUT circuitry that the FSC algorithm is active and that the LUT
values are TACH Target settings. This is the default setting.
Bits 3-2 - TEMP3_CFG = ‘10’b tells the Look Up Table to reference the Forced Temperature 1 data
instead of the External Diode 3 data or the TRIP_SET / VIN4 data.
Bits 1- 0- TEMP4_CFG = ‘10b’ tells the Look Up Table to reference the Forced Temeprature 2 data
instead of the Internal Diode data or the External Diode 4 data.
Table B.9 Fan Speed Control Table Example #3
FAN
SPEED
STEP #
EXTERNAL DIODE
1 TE MPERATURE
(CPU)
EXTERNAL
DIODE 2
TEMPERATURE
(GPU)
PUSHED
TEMPERATURE
SETTING (DTS1)
PUSHED
TEMPERATURE
SETTING (DTS2) TACH
TARGET
135
oC65
oC50
oC40
oCEFh
(1028 RPM)
240
oC75
oC55
oC45
oCA3h
(1508 RPM)
350
oC85
oC60
oC50
oC7Ah
(2014 RPM)
460
oC90
oC65
oC55
oC62h
(2508 RPM)
570
oC95
oC70
oC60
oC52h
(2997 RPM)
680
oC 100oC75
oC65
oC3Dh
(4029 RPM)
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Note: The values shown in Table B.9 are example settings. All the cells in the look-up table are
programmable via SMBus.
790
oC 105oC80
oC80
oC31h
(5016 RPM)
8100
oC110
oC85
oC 100oC29h
(5994 RPM)
Table B.10 Fan Speed Determination for Example #3 (us in g settings in Table B.9)
EXTERNAL
DIODE 1
TEMPERATURE
(CPU)
EXTERNAL
DIODE 2
TEMPERATURE
(GPU)
PUSHED
TEMPERATURE
(DTS1)
PUSHED
TEMPERATURE
(DTS2) FAN DRIVE
SETTING RESULT
Example 1: 75°C 75°C 35°C
(translated as 65°C) 50°C
(translated as 50°C) 52h (2997 RPM) -
CPU requires highest
target
Example 2: 75°C 90°C 15°C
(translated as
85°C)
20°C
(translated as 80°C) 29h (5994 RPM) -
DTS1 requires
highest target
Example 3: 75°C 97.25°C 30°C
(translated as 70°C)
23°C
(translated as
77°C)
3Dh (40296 RPM) -
DTS2 requires
highest target
Table B.9 Fan Speed Control Table Example #3 (con tinued)
FAN
SPEED
STEP #
EXTERNAL DIODE
1 TE MPERATURE
(CPU)
EXTERNAL
DIODE 2
TEMPERATURE
(GPU)
PUSHED
TEMPERATURE
SETTING (DTS1)
PUSHED
TEMPERATURE
SETTING (DTS2) TACH
TARGET
RPM-Based High Side Fan Controller with Hardware Thermal Sh utdown
Datasheet
SMSC EMC2105 89 Revision 1.78 (04-21-09)
DATASHEET
Chapter 8 Revision History
Table 8.1 Customer Revision History
REVISION LEVEL & DATE SECTION/FIGURE/ENTRY CORRECTION
Rev. 1.78 (04-21-09)
Table 3.2, "Electrical
Specifications" Added electrical specs for SMbus delay and time
to first conversion
Section 7.2, "Package
Markings" Added figures for package markings
Rev. 1.77 (03-16-09) RPM Appe ndix Removed this appendix to consolidate information
in application note
Rev. 1.76 (03-11-09) Section 6.28, "TACH
Reading Registers" Added reference to application note AN17.4
Rev. 1.75 (03-06-09) Appendix B "Look Up Table
Operation" Updated entire section - examples were incorrect
for RPM values and fleshed out bit descriptions
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Authorized Distributor
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Microchip:
EMC2105-BP-TR