Doc. No. 102287H
May 2, 2012
CX86500 SCXV.xx
V.92/V.34/V.32bis Modem in 28-Pin or
38-Pin TSSOP with CX20493 SmartDAA
Data Sheet
CX86500 SCXV.xx Modem Data Sheet
ii Conexant 102287H
Revision Record
Revision
Date
Comments
A
9/29/2003
Initial release.
B
11/4/2003
Rev. B release.
C
12/19/2003
Rev. C release.
D
2/9/2004
Rev. D release.
E
3/18/2004
Rev. E release.
F
7/19/2004
Rev. F release.
G
1/17/2012
Rev. G release.
H
5/2/2012
Rev. H release.
© 2003, 2004, 2012, Conexant Systems, Inc.
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CX86500 SCXV.xx Modem Data Sheet
102287H Conexant iii
Contents
1. Introduction .......................................................................................................................... 1-1
1.1 Overview ................................................................................................................................................... 1-1
1.2 Features .................................................................................................................................................... 1-3
1.2.1 Applications ................................................................................................................................ 1-4
1.3 Technical Overview ................................................................................................................................... 1-4
1.3.1 General Description .................................................................................................................... 1-4
1.3.2 Embedded MCU Firmware ......................................................................................................... 1-4
1.3.3 Operating Modes ........................................................................................................................ 1-4
1.3.3.1 Data Modes ............................................................................................................... 1-4
1.3.3.2 V.44 Data Compression ............................................................................................ 1-5
1.3.3.3 Synchronous Access Mode (SAM) - Video Conferencing ......................................... 1-5
1.3.3.4 Voice Pass-Through Mode ........................................................................................ 1-5
1.3.3.5 Worldwide Operation ................................................................................................. 1-6
1.3.4 Reference Designs ..................................................................................................................... 1-7
1.4 Hardware Description ................................................................................................................................ 1-8
1.4.1 CX86500 Modem ........................................................................................................................ 1-8
1.4.2 Digital Isolation Barrier ................................................................................................................ 1-8
1.4.3 CX20493 SmartDAA Line Side Device ....................................................................................... 1-8
1.5 Commands ................................................................................................................................................ 1-9
2. Technical Specifications ....................................................................................................... 2-1
2.1 Serial DTE Interface Operation ................................................................................................................. 2-1
2.1.1 Automatic Speed/Format Sensing .............................................................................................. 2-1
2.2 Parallel Host Bus Interface Operation ....................................................................................................... 2-1
2.3 Establishing Data Modem Connections .................................................................................................... 2-2
2.3.1 Dialing ......................................................................................................................................... 2-2
2.3.2 Modem Handshaking Protocol .................................................................................................... 2-2
2.3.3 Call Progress Tone Detection ..................................................................................................... 2-2
2.3.4 Answer Tone Detection ............................................................................................................... 2-2
2.3.5 Ring Detection ............................................................................................................................ 2-2
2.3.6 Billing Protection ......................................................................................................................... 2-2
2.3.7 Connection Speeds .................................................................................................................... 2-3
2.3.8 Automode ................................................................................................................................... 2-3
2.4 Data Mode ................................................................................................................................................ 2-3
2.4.1 Speed Buffering (Normal Mode) ................................................................................................. 2-3
2.4.2 Flow Control ................................................................................................................................ 2-3
2.4.3 Escape Sequence Detection ....................................................................................................... 2-4
2.4.4 BREAK Detection ....................................................................................................................... 2-4
2.4.5 Telephone Line Monitoring ......................................................................................................... 2-4
2.4.6 Fall Forward/Fallback (V.92/V.90/V.34/V.32 bis/V.32) ................................................................ 2-4
2.4.7 Retrain ........................................................................................................................................ 2-4
2.4.8 Programmable Inactivity Timer ................................................................................................... 2-4
CX86500 SCXV.xx Modem Data Sheet
iv Conexant 102287H
2.4.9 DTE Signal Monitoring (Serial DTE Interface Only) .................................................................... 2-4
2.4.10 Call Progress Speaker Interface ................................................................................................. 2-5
2.4.11 Serial EEPROM Interface ........................................................................................................... 2-5
2.5 V.92 Features............................................................................................................................................ 2-5
2.5.1 Modem-on-Hold .......................................................................................................................... 2-5
2.5.2 Quick Connect ............................................................................................................................ 2-5
2.5.3 PCM Upstream ........................................................................................................................... 2-5
2.6 Error Correction and Data Compression ................................................................................................... 2-6
2.6.1 V.42 Error Correction .................................................................................................................. 2-6
2.6.2 MNP 2-4 Error Correction ........................................................................................................... 2-6
2.6.3 V.44 Data Compression .............................................................................................................. 2-6
2.6.4 V.42 bis Data Compression ........................................................................................................ 2-6
2.6.5 MNP 5 Data Compression .......................................................................................................... 2-7
2.7 Voice Pass-Through Mode ........................................................................................................................ 2-7
2.8 Telephony Extensions ............................................................................................................................... 2-7
2.8.1 Line-in-Use Detection ................................................................................................................. 2-7
2.8.2 Extension Pick-up Detection ....................................................................................................... 2-7
2.8.3 Remote Hang-up Detection ........................................................................................................ 2-8
2.9 Point-of-Sales Support .............................................................................................................................. 2-8
2.10 Tone Detectors .......................................................................................................................................... 2-8
2.11 Call Waiting Tone Detection ...................................................................................................................... 2-8
2.12 Caller ID .................................................................................................................................................... 2-8
2.13 Worldwide Country Support ...................................................................................................................... 2-9
2.14 Diagnostics ............................................................................................................................................... 2-9
2.15 Low Power Modes ................................................................................................................................... 2-10
3. Hardware Interface ............................................................................................................... 3-1
3.1 CX86500 Hardware 28-Pin TSSOP with Serial Interface .......................................................................... 3-1
3.1.1 CX86500 Modem 28-Pin TSSOP with Serial Interface Signal Summary .................................... 3-1
3.1.1.1 LSD Interface (Through DIB) .................................................................................... 3-1
3.1.1.2 Call Progress Speaker Interface ............................................................................... 3-1
3.1.1.3 Serial DTE Interface and Indicator Outputs ............................................................... 3-1
3.1.2 CX86500 Modem 28-Pin TSSOP with Serial Interface Pin Assignments and Signal
Definitions ................................................................................................................................... 3-2
3.2 CX86500 Modem 38-Pin TSSOP with Serial or Parallel Interface Hardware Pins and Signals ................ 3-6
3.2.1 CX86500 Modem 38-Pin TSSOP with Serial Interface Signal Summary .................................... 3-6
3.2.1.1 LSD Interface (Through DIB) .................................................................................... 3-6
3.2.1.2 Call Progress Speaker Interface ............................................................................... 3-6
3.2.1.3 Serial EEPROM Interface ......................................................................................... 3-6
3.2.1.4 Serial DTE Interface and Indicator Outputs ............................................................... 3-6
3.2.2 CX86500 Modem 38-Pin TSSOP with Serial Interface Pin Assignments and Signal
Definitions ................................................................................................................................... 3-7
3.2.3 CX86500 Modem 38-Pin TSSOP with Parallel Interface Signal Summary ............................... 3-11
3.2.3.1 LSD Interface (Through DIB) .................................................................................. 3-11
3.2.3.2 Call Progress Speaker Interface ............................................................................. 3-11
3.2.3.3 Serial EEPROM Interface ....................................................................................... 3-11
3.2.3.4 Parallel Host Bus Interface ...................................................................................... 3-11
3.2.4 CX86500 Modem 38-Pin TSSOP with Parallel Interface Pin Assignments and Signal
Definitions ................................................................................................................................. 3-12
3.3 CX86500 Electrical Characteristics ......................................................................................................... 3-16
3.4 CX20493 LSD 28-Pin QFN Hardware Pins and Signals ......................................................................... 3-17
3.4.1 CX20493 LSD 28-Pin QFN Signal Summary ........................................................................... 3-17
3.4.1.1 CX86500 Interface (Through DIB) ........................................................................... 3-17
CX86500 SCXV.xx Modem Data Sheet
102287H Conexant v
3.4.1.2 Telephone Line Interface ........................................................................................ 3-17
3.4.1.3 Voltage References ................................................................................................. 3-17
3.4.1.4 General Purpose Input/Output ................................................................................ 3-18
3.4.1.5 No Connects ........................................................................................................... 3-18
3.4.2 CX20493 LSD Pin Assignments and Signal Definitions ............................................................ 3-18
3.5 CX20493 LSD 32-Pin LQFP Hardware Pins and Signals ....................................................................... 3-22
3.5.1 CX20493 LSD 32-Pin LQFP Signal Summary .......................................................................... 3-22
3.5.1.1 CX86500 Interface (Through DIB) ........................................................................... 3-22
3.5.1.2 Telephone Line Interface ........................................................................................ 3-22
3.5.1.3 Voltage References ................................................................................................. 3-22
3.5.1.4 General Purpose Input/Output ................................................................................ 3-23
3.5.1.5 No Connects ........................................................................................................... 3-23
3.5.2 CX20493 LSD 32-Pin LQFP Pin Assignments and Signal Definitions ...................................... 3-23
3.6 CX20493 LSD GPIO DC Electrical Characteristics ................................................................................. 3-27
3.7 Electrical and Environmental Specifications ............................................................................................ 3-28
3.7.1 Operating Conditions, Absolute Maximum Ratings, and Power Requirements ........................ 3-28
3.7.2 Interface and Timing Waveforms .............................................................................................. 3-30
3.7.2.1 Serial DTE Interface ................................................................................................ 3-30
3.7.2.2 Parallel Host Bus Interface ...................................................................................... 3-31
3.7.2.3 Voice Pass-Through Interface – 14-Bit PCM .......................................................... 3-33
3.8 Crystal and Clock Specifications ............................................................................................................. 3-33
4. Parallel Host Interface .......................................................................................................... 4-1
4.1 Overview ................................................................................................................................................... 4-1
4.2 Register Signal Definitions ........................................................................................................................ 4-3
4.2.1 IER - Interrupt Enable Register (Addr = 1, DLAB = 0) ................................................................ 4-3
4.2.2 FCR - FIFO Control Register (Addr = 2, Write Only) ................................................................... 4-4
4.2.3 IIR - Interrupt Identifier Register (Addr = 2) ................................................................................. 4-5
4.2.4 LCR - Line Control Register (Addr = 3) ....................................................................................... 4-6
4.2.5 MCR - Modem Control Register (Addr = 4) ................................................................................. 4-7
4.2.6 LSR - Line Status Register (Addr = 5) ........................................................................................ 4-7
4.2.7 MSR - Modem Status Register (Addr = 6) .................................................................................. 4-9
4.2.8 RBR - RX Buffer (Receiver Buffer Register) (Addr = 0, DLAB = 0) ............................................. 4-9
4.2.9 THR - TX Buffer (Transmitter Holding Register) (Addr = 0, DLAB = 0) ....................................... 4-9
4.2.10 Divisor Registers (Addr = 0 and 1, DLAB = 1) .......................................................................... 4-10
4.3 Receiver FIFO Interrupt Operation .......................................................................................................... 4-10
4.3.1 Receiver Data Available Interrupt ............................................................................................. 4-10
4.3.2 Receiver Character Timeout Interrupts ..................................................................................... 4-11
4.4 Transmitter FIFO Interrupt Operation ...................................................................................................... 4-11
4.4.1 Transmitter Empty Interrupt ...................................................................................................... 4-11
5. Package Dimensions ........................................................................................................... 5-1
6. Recommended TSSOP Surface Mount Land Pattern .......................................................... 6-1
CX86500 SCXV.xx Modem Data Sheet
vi Conexant 102287H
Figures
Figure 1-1. SCXV.xx Modem Simplified Interface Diagram .......................................................................... 1-2
Figure 3-1. CX86500 Modem 28-Pin TSSOP with Serial Interface Hardware Signals .................................. 3-2
Figure 3-2. CX86500 Modem 28-Pin TSSOP with Serial Interface Pin Signals ............................................ 3-3
Figure 3-3. CX86500 Modem 38-Pin TSSOP with Serial Interface Hardware Signals .................................. 3-7
Figure 3-4. CX86500 Modem 38-Pin TSSOP with Serial Interface Pin Signals ............................................ 3-8
Figure 3-5. CX86500 Modem 38-Pin TSSOP with Parallel Interface Hardware Signals ............................. 3-12
Figure 3-6. CX86500 Modem 38-Pin TSSOP with Parallel Interface Pin Signals ....................................... 3-13
Figure 3-7. CX20493 LSD 28-Pin QFN Hardware Interface Signals ........................................................... 3-18
Figure 3-8. CX20493 LSD 28-Pin QFN Pin Signals .................................................................................... 3-19
Figure 3-9. CX20493 LSD 32-Pin LQFP Hardware Interface Signals ......................................................... 3-23
Figure 3-10. CX20493 LSD 32-Pin LQFP Pin Signals ................................................................................ 3-24
Figure 3-11. Waveforms - Serial DTE Interface .......................................................................................... 3-30
Figure 3-12. Waveforms - Parallel Host Bus ............................................................................................... 3-32
Figure 3-13. Waveforms – 14-Bit PCM Receive and Transmit Timing ........................................................ 3-33
Figure 5-1. Package Dimensions - 28-Pin TSSOP ....................................................................................... 5-2
Figure 5-2. Package Dimensions - 38-Pin TSSOP ....................................................................................... 5-3
Figure 5-3. Package Dimensions - 28-Pin QFN: Punch Style ....................................................................... 5-4
Figure 5-4. Package Dimensions – 28-Pin QFN: Sawn Style ....................................................................... 5-5
Figure 5-5. Package Dimensions - 32-Pin LQFP ......................................................................................... 5-6
Figure 6-1. Recommended TSSOP Surface Mount Land Pattern ................................................................ 6-1
CX86500 SCXV.xx Modem Data Sheet
102287H Conexant vii
Tables
Table 1-1. SCXV.xx Modem Models and Functions ..................................................................................... 1-2
Table 1-2. Default Countries Supported ........................................................................................................ 1-6
Table 2-1. +MS Command Automode Connectivity ...................................................................................... 2-3
Table 3-1. CX86500 Modem 28-Pin TSSOP with Serial Interface Pin Signals ............................................. 3-3
Table 3-2. CX86500 Modem 28-Pin TSSOP with Serial Interface Hardware Signal Definitions ................... 3-4
Table 3-3. CX86500 Modem 38-Pin TSSOP with Serial Interface Pin Signals ............................................. 3-8
Table 3-4. CX86500 Modem 38-Pin TSSOP with Serial Interface Hardware Signal Definitions ................... 3-9
Table 3-5. CX86500 Modem 38-Pin TSSOP with Parallel Interface Pin Signals ........................................ 3-13
Table 3-6. CX86500 Modem 38-Pin TSSOP with Parallel Interface Hardware Signal Definitions .............. 3-14
Table 3-7. CX86500 Modem I/O Type Definitions ...................................................................................... 3-16
Table 3-8. CX86500 Modem DC Electrical Characteristics ......................................................................... 3-16
Table 3-9. CX20493 LSD 28-Pin QFN Pin Signals ..................................................................................... 3-19
Table 3-10. CX20493 LSD 28-Pin QFN Hardware Signal Definitions ......................................................... 3-20
Table 3-11. CX20493 LSD 32-Pin LQFP Pin Signals ................................................................................. 3-24
Table 3-12. CX20493 LSD 32-Pin LQFP Pin Signal Definitions ................................................................. 3-25
Table 3-13. CX20493 LSD GPIO DC Electrical Characteristics .................................................................. 3-27
Table 3-14. CX20493 AVdd DC Electrical Characteristics .......................................................................... 3-27
Table 3-15. Operating Conditions ............................................................................................................... 3-28
Table 3-16. Absolute Maximum Ratings ..................................................................................................... 3-28
Table 3-17. Current and Power Requirements ........................................................................................... 3-29
Table 3-18. Timing - Parallel Host Bus ....................................................................................................... 3-31
Table 3-19. Crystal Specifications .............................................................................................................. 3-33
Table 3-20. Clock Specifications ................................................................................................................. 3-33
Table 4-1. Parallel Interface Registers .......................................................................................................... 4-2
Table 4-2. Interrupt Sources and Reset Control ........................................................................................... 4-5
Table 4-3. Programmable Baud Rates ........................................................................................................ 4-10
Table 5-1. Package Dimensions: Punch Style and Sawn Style .................................................................... 5-5
CX86500 SCXV.xx Modem Data Sheet
viii Conexant 102287H
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CX86500 SCXV.xx Modem Data Sheet
102287H Conexant 1-1
1. Introduction
1.1 Overview
The Conexant SCXV.92, SCXV.34, and SCXV.32bis modems are worldwide
operational modem device sets for embedded applications that support modulations up to
V.92, V.34, and V.32bis, respectively (refer to Table 1-1). All modems also support
V.44/V.42bis/MNP 5 data compression for greater data throughput, V.42 LAPM/MNP2-
4 error correction protocol for increased data integrity and reliability.
The SCXV.92/V.34/V.32bis device set consists of a modem device and a SmartDAA 3
Line Side Device (LSD). The modem device integrates a microcontroller (MCU), a
digital signal processor (DSP), and a SmartDAA system side device (SSD) onto a single
die. The modem is available in 28-pin or 38-pin TSSOP versions. The 28-pin version is
for serial interface applications and is footprint-compatible with the CX84100
(SCXV.22bis) and CX81801-9x (SmartV.XX) modem devices. The 38-pin version is for
serial or parallel interface applications (interface type selectable by an I/O pin). Major
hardware interfaces are illustrated in Figure 1-1.
Conexant’s SmartDAA technology used in the SmartDAA 3 LSD eliminates the need for
bulky analog transformers, relays, and opto-isolators typically used in discrete DAA
implementations. The SmartDAA 3 LSD operates without drawing power from the phone
line, unlike line-powered DAAs, and is therefore not subject to variations in line voltage
conditions. The SmartDAA 3 LSD also adds enhanced telephony extension features to
the modem’s operation and other functions such as Call Waiting detection, and Caller ID
decoding. Incorporating Conexant’s proprietary Digital Isolation Barrier (DIB) design
and other innovative DAA features, the SmartDAA architecture simplifies application
design and minimizes layout area to reduce design cost. The SmartDAA 3 LSD is
available in a 28-pin Quad Flat No-lead (QFN) package or in a 32-pin Low Profile Quad
Pack (LQFP) package.
The modem operates by executing masked code from internal ROM. The modem features
internal RAM memory that enhances the modem's flexibility. The modem's internal
RAM can be used to load new country profiles, override existing country profiles or add
customized firmware code. An optional external serial NVRAM is supported by the 38-
pin version. The optional external NVRAM adds the convenience of permanent storage,
just like internal RAM, NVRAM can be used to store new country profiles, override
existing ones or add customized firmware code.
Small, low-profile packages, reduced voltage operation, and low power consumption
make this device set an ideal solution for embedded applications.
CX86500 SCXV.xx Modem Data Sheet
1-2 Conexant 102287H
Table 1-1. SCXV.xx Modem Models and Functions
Model/Order/Part Numbers*
Supported Functions
Marketing Name
Device Set Order
No.
SCXV.xx
Modem
[28-Pin
TSSOP]
Part No.
V.92 Data, QC,
MOH, PCM
V.34 Data
V.32bis Data
Device Sets with CX86500 in 28-Pin TSSOP
SCXV.92
DSCX-V92LF-025
CX86500-25
Y
Y
Y
SCXV.34
DSCX-V34LF-026
CX86500-26
-
Y
Y
SCXV.32bis
DSCX-V32LF-027
CX86500-27
-
-
Y
Marketing Name
Device Set Order
No.
SCXV.xx
Modem
[38-Pin
TSSOP]
Part No.
V.92 Data, QC,
MOH, PCM
V.34 Data
V.32bis Data
Device Sets with CX86500 in 38-Pin TSSOP
SCXV.92
DSCX-V92LF-065
CX86500-65
Y
Y
Y
SCXV.34
DSCX-V34LF-066
CX86500-66
-
Y
Y
SCXV.32bis
DSCX-V32LF-067
CX86500-67
-
-
Y
Notes:
All devices are lead (Pb) free.
Supported functions (Y=Supported; - = Not supported)
QC, MOH, PCM Quick connect, Modem-on-Hold, PCM upstream
* Contact your local Conexant sales representative for ordering information about device sets with the 32-pin LQFP CX20493 Line Side
Device
Figure 1-1. SCXV.xx Modem Simplified Interface Diagram
V.92/V.34/V.32bis Modem
28-Pin or 38-Pin TSSOP
MCU/DSP/
SmartDAA
Interface
DTE/Host
Interface
Serial or
Parallel*
Interface
102387_001
RAM TIP
RING
External
Discrete
Components
Telephone
Line
Digital Isolation
Barrier (DIB)
Components
CX20493
SmartDAA 3
Line Side Device (LSD)
28-Pin QFN or 32-Pin LQFP
Line Side
DIB
Interface
(LSDI)
Codec
Telephone
Line
Interface
DAA Hardware
ROM
Optional
NVRAM*
* 38-pin version only.
28.224 MHz
or
27.000 MHz
Crystal orClock
Source
CX86500 SCXV.xx Modem Data Sheet
102287H Conexant 1-3
1.2 Features
Modulations and protocols
ITU-T V.92
Modem-on-Hold (MOH)
Quick connect (QC)
PCM upstream
V.90/V.34/V.32bis/V.32
V.22bis/V.22/V.23/V.21
V.23 reverse, V.23 half-duplex
Bell 212A/Bell 103
V.29 FastPOS
V22bis fast connect
V.80 Synchronous Access Mode
Data compression
V.44/V.42bis/MNP5
Error correction
V.42/MNP 4/MNP 2
Call Waiting (CW) detection
Type I and Type II Caller ID (CID) decoding
DTE/host interface
Serial DTE interface
Parallel 16550 UART-compatible host interface (38-pin version)
Direct Mode
Synchronous Mode
Asynchronous Mode
No external memory required
Sixty-three embedded and upgradeable country profiles
Serial NVRAM interface for optional permanent country profile storage (38-pin
version)
Embedded AT commands
Full-duplex Voice Pass-Through Mode
Mu-Law, A-Law (serial and parallel host interface)
14-bit PCM (parallel host interface only)
SmartDAA
Extension pick-up detection
Digital line protection
Line reversal detection
Line-in-use detection
Remote hang-up detection
Worldwide compliance
CX86500 SCXV.xx Modem Data Sheet
1-4 Conexant 102287H
Selectable 28.224 MHz or 27.000 MHz frequency of operation
Low power and voltage
Single +3.3V supply
Low power consumption mode
+3.3V I/O level
Compact, robust board design
Small, low-profile modem packages
SmartDAA and DIB technologies
Reference design supports 5KV isolation
1.2.1 Applications
Set top boxes
Point-of-Sale terminals
ATM machines
Metering terminals
Video game consoles
Internet appliances
1.3 Technical Overview
1.3.1 General Description
Modem operation, including dialing, call progress, telephone line interface, telephone
handset interface, and host DTE interface functions are supported and controlled through
the V.250 and V.251-compatible command set.
The OEM adds a crystal circuit, DIB components, telephone line interface, telephone
handset/telephony extension interface, and other supporting discrete components as
supported by the modem model (Table 1-1) and required by the application to complete
the system.
1.3.2 Embedded MCU Firmware
Embedded MCU firmware performs processing of general modem control, command
sets, data modem, error correction and data compression (ECC), worldwide, V.80, and
serial DTE host interface functions according to modem models (Table 1-1).
1.3.3 Operating Modes
1.3.3.1 Data Modes
In V.92 data modem mode (V.92 models), the modem can receive data from a digital
source using a V.92-compatible central site modem at line speeds up to 56 kbps. With
PCM upstream enabled, data transmission supports sending data at line speeds up to
48 kbps. When PCM upstream is disabled, data transmission supports sending data at
line speeds up to V.34 rates. This mode can fallback to V.34 mode and to lower rates as
dictated by line conditions.
CX86500 SCXV.xx Modem Data Sheet
102287H Conexant 1-5
The following modes are also supported in V.92 models, when connected to a V.92-
compatible server supporting the feature listed.
Quick connect, which allows quicker subsequent connection to a server using stored
line parameters obtained during the initial connection. The server must support quick
connect profiles.
Modem-on-Hold, which allows detection and reporting of incoming phone calls on
the PSTN with enabled Call Waiting. If the incoming call is accepted by the user, the
user has a pre-defined amount of time of holding the data connection for a brief
conversation. The data connection resumes upon incoming call termination. The
server must support Modem-on-Hold functionality.
PCM upstream, which boosts the upstream data rates between the user and V.92
server. A maximum of 48 kbps upstream rate is supported when connected to a V.92
server that supports PCM upstream.
In V.34 data modem mode (V.92 and V.34 models), the modem can operate in 2-wire,
full-duplex, asynchronous modes at line rates up to 33.6 kbps. Data modem modes
perform complete handshake and data rate negotiations. Using V.34 modulation to
optimize modem configuration for line conditions, the modem can connect at the highest
data rate that the channel can support from 33600 bps down to 2400 bps with automatic
fallback. Automode operation in V.34 is provided in accordance with PN3320 and in
V.32 bis in accordance with PN2330. All tone and pattern detection functions required by
the applicable ITU or Bell standards are supported.
In V.32 bis data modem mode, the modem can operate at line speeds up to 14.4 kbps.
1.3.3.2 V.44 Data Compression
V.44 provides more efficient data compression than V.42 bis that significantly decreases
the download time for the types of files associated with Internet use. This significant
improvement is most noticeable when browsing and searching the web since HTML text
files are highly compressible. (The improved performance amount varies both with the
actual format and with the content of individual pages and files.)
1.3.3.3 Synchronous Access Mode (SAM) - Video Conferencing
V.80 Synchronous Access Mode between the modem and the host/DTE is provided for
host-controlled communication protocols, e.g., H.324 video conferencing applications.
1.3.3.4 Voice Pass-Through Mode
Voice Pass-Through Mode supports data transfer sampled at 8 KHz. Mu-Law and A-Law
are supported both in serial and parallel modes. 14-bit PCM is supported in parallel mode
only.
CX86500 SCXV.xx Modem Data Sheet
1-6 Conexant 102287H
1.3.3.5 Worldwide Operation
The modem operates in TBR21-compliant and other countries. Country-dependent
modem parameters for functions such as dialing, carrier transmit level, calling tone, call
progress tone detection, answer tone detection, blacklisting, caller ID, and relay control
are programmable.
SmartDAA technology allows a single PCB design and single BOM to be homologated
worldwide. Advanced features such as extension pick-up detection, remote hang-up
detection, line-in-use detection, and digital PBX line protection are supported.
Country code IDs are defined by ITU-T T.35.
Internal ROM includes default profiles for 63 countries including TBR21-compliant
profiles. An additional or modified country profile can be loaded into internal SRAM. A
duplicate country profile stored in internal SRAM will override the profile in internal
ROM firmware. Additional country profiles can be loaded into external NVRAM for
permanent storage (38-pin version only). The default countries supported are listed in
Table 1-2. Request additional country profiles from a Conexant Sales Office.
Table 1-2. Default Countries Supported
Country
Country
Code
Call Waiting Tone
Detection (CW)
Supported
On-Hook Type 1
Caller ID (CID)
Supported
Off-Hook Type 2
Caller ID (CID2)
Supported
Argentina
7
Australia
9
X
X
Austria
0A
X
X
Belgium
0F
X
Brazil
16
X
Bulgaria
1B
Canada
20
X
X
X
Chile
25
X
China
26
X
X
Colombia
27
Croatia
FA
Cyprus
2D
Czech Republic
2E
Denmark
31
X
X
Egypt
36
Estonia
F9
Finland
3C
X
X
France
3D
X
X
X
Germany
42
X
X
Greece
46
X
Hong Kong
50
X
X
X
Hungary
51
Iceland
52
India
53
X
Indonesia
54
Ireland
57
X
X
X
Israel
58
X
Italy
59
X
X
Japan
00
X
X
X
Korea
61
X
X
CX86500 SCXV.xx Modem Data Sheet
102287H Conexant 1-7
Table 1-2. Default Countries Supported (Continued)
Country
Country
Code
Call Waiting Tone
Detection (CW)
Supported
On-Hook Type 1
Caller ID (CID)
Supported
Off-Hook Type 2
Caller ID (CID2)
Supported
Kuwait
62
Lebanon
64
Luxembourg
69
Malaysia
6C
X
Mexico
73
Morocco
77
Netherlands
7B
X
New Zealand
7E
X
X
Norway
82
X
X
Pakistan
84
Philippines
89
Poland
8A
X
Portugal
8B
X
Romania
8E
Russia
B8
Saudi Arabia
98
Senegal
99
Singapore
9C
X
X
X
Slovakia
FB
Slovenia
FC
South Africa
9F
X
Spain
A0
X
X
Sri Lanka
A1
Sweden
A5
X
X
Switzerland
A6
X
Taiwan
FE
X
X
Thailand
A9
Tunisia
AD
Turkey
AE
UK
B4
X
X
X
United Arab Emirates
B3
Uruguay
B7
USA
B5
X
X
X
Reserved
FD
1.3.4 Reference Designs
A reference design is available to minimize modem design time, reduce development
cost, and accelerate market entry.
A design package is available in electronic form. This package includes schematics, bill
of materials (BOM), vendor part list (VPL), board layout files in Gerber and PADS
formats, and complete documentation.
CX86500 SCXV.xx Modem Data Sheet
1-8 Conexant 102287H
1.4 Hardware Description
1.4.1 CX86500 Modem
The CX86500 modem, packaged in a 28-pin TSSOP and 38-pin TSSOP, includes a
Microcontroller (MCU), a Modem Data Pump (MDP), internal ROM, internal RAM, and
SmartDAA interface functions.
The modem connects to host via a logical V.24 (EIA/TIA-232-E) serial DTE interface or
a parallel 16550 UART-compatible host interface (38-pin only).
The modem MCU/DSP performs the command processing, host interface functions and
telephone line signal modulation/demodulation which reduces computational load on the
host processor.
The SmartDAA Interface communicates with, and supplies power and clock to the LSD
through the DIB.
1.4.2 Digital Isolation Barrier
The OEM-supplied Digital Isolation Barrier (DIB) electrically DC isolates the CX86500
from the LSD and telephone line. The modem is connected to a fixed digital ground and
operates with standard CMOS logic levels. The LSD is connected to a floating ground
and can tolerate high voltage input (compatible with telephone line and typical surge
requirements).
The DIB transformer couples power and clock from the CX86500 to the LSD.
The DIB data channel supports bidirectional half-duplex serial transfer of data, control,
and status information between the CX86500 and the LSD over two lines.
1.4.3 CX20493 SmartDAA Line Side Device
The CX20493 SmartDAA Line Side Device (LSD) includes a Line Side DIB Interface
(LSDI), a coder/decoder (codec), and a Telephone Line Interface (TLI).
The LSDI communicates with, and receives power and clock from, the SmartDAA
interface in the CX86500 through the DIB.
LSD power is received from the MDP PWRCLKP and PWRCLKN pins via the DIB
through a full-wave rectifier bridge and capacitive power filter circuit connected to the
DIB transformer secondary winding.
The CLK input is also accepted from the DIB transformer secondary winding through a
capacitor and a resistor in series.
Information is transferred between the LSD and the CX86500 through the DIB_P and
DIB_N pins. These pins connect to the CX86500 DIB_DATAP and DIB_DATAN pins,
respectively, through the DIB.
The TLI integrates DAA and direct telephone line interface functions and connects
directly to the line TIP and RING pins, as well as to external line protection components.
Direct LSD connection to TIP and RING allows real-time measurement of telephone line
parameters, such as the telephone central office (CO) battery voltage, individual
telephone line (copper wire) resistance, and allows dynamic regulation of the off-hook
TIP and RING voltage and total current drawn from the central office (CO). This allows
the modem to maintain compliance with U.S. and worldwide regulations and to actively
control the DAA power dissipation.
CX86500 SCXV.xx Modem Data Sheet
102287H Conexant 1-9
1.5 Commands
The modem supports data modem and V.80 commands, and S Registers in accordance
with modem model options. See Doc. No. 102184 for a description of the commands.
Data Modem Operation. Data modem functions operate in response to the AT
commands when +FCLASS=0. Default parameters support U.S./Canada operation.
CX86500 SCXV.xx Modem Data Sheet
1-10 Conexant 102287H
This page is intentionally blank.
CX86500 SCXV.xx Modem Data Sheet
102287H Conexant 2-1
2. Technical Specifications
2.1 Serial DTE Interface Operation
2.1.1 Automatic Speed/Format Sensing
Command Mode and Data Mode. The modem can automatically determine the speed
and format of the data sent from the DTE. The modem can sense speeds of 300, 600,
1200, 2400, 4800, 7200, 9600, 12000, 14400, 16800, 19200, 21600, 24000, 26400,
28800, 38400, 57600, and 115200 bps and the following data formats:
Parity
Data Length
(No. of Bits)
No. of
Stop Bits
Character Length
(No. of Bits)
None
7
2
10
Odd
7
1
10
Even
7
1
10
None
8
1
10
Odd
8
1
11*
Even
8
1
11*
*11-bit characters are sensed, but the parity bit is stripped off during
data transmission in Normal and Error Correction modes.
The modem can speed sense data with mark or space parity and configures itself as
follows:
DTE Configuration
Modem Configuration
7 mark
7 none
7 space
8 none
8 mark
8 none
8 space
8 even
2.2 Parallel Host Bus Interface Operation
Command Mode and Data Mode. The modem can operate at rates up to 230.4 kbps by
programming the Divisor Latch in the parallel interface registers. Refer to Chapter 4.
CX86500 SCXV.xx Modem Data Sheet
2-2 Conexant 102287H
2.3 Establishing Data Modem Connections
2.3.1 Dialing
DTMF Dialing. DTMF dialing using DTMF tone pairs is supported in accordance with
ITU-T Q.23.
Pulse Dialing. Pulse dialing is supported in accordance with EIA/TIA-496-A.
Blind Dialing. The modem can blind dial in the absence of a dial tone if enabled by the
X0, X1, or X3 command.
2.3.2 Modem Handshaking Protocol
If a tone is not detected within the time specified in the S7 register after the last digit is
dialed, the modem aborts the call attempt.
2.3.3 Call Progress Tone Detection
Ringback, equipment busy, congested tone, warble tone, and progress tones can be
detected in accordance with the applicable standard.
2.3.4 Answer Tone Detection
Answer tone can be detected over the frequency range of 2100 ± 40 Hz in ITU-T modes
and 2225 ± 40 Hz in Bell modes.
2.3.5 Ring Detection
A ring signal can be detected from a TTL-compatible 15.3 Hz to 68 Hz square wave
input.
2.3.6 Billing Protection
When the modem goes off-hook to answer an incoming call, both transmission and
reception of data are prevented for 2 seconds to allow transmission of the billing tone
signal.
CX86500 SCXV.xx Modem Data Sheet
102287H Conexant 2-3
2.3.7 Connection Speeds
The modem functions as a data modem when the +FCLASS=0 command is active.
Line connection can be selected using the +MS command. The +MS command selects
modulation, enables/disables automode, and selects minimum and maximum line speeds
(Table 2-1).
Table 2-1. +MS Command Automode Connectivity
Modulation
<carrier>
Possible (<min_rx_rate>, <min_rx_rate>, (<min_tx_rate>),
and <max_tx_rate>) Rates (bps)
Bell 103
B103
300
Bell 212
B212
1200 Rx/75 Tx or 75 Rx/1200 Tx
V.21
V21
300
V.22
V22
1200
V.22 bis
V22B
2400 or 1200
V.23
V23C
1200
V.32
V32
9600 or 4800
V.32 bis
V32B
14400, 12000, 9600, 7200, or 4800
V.34
V34
33600, 31200, 28800, 26400, 24000, 21600, 19200, 16800,
14400, 12000, 9600, 7200, 4800, or 2400
V.90
V90
56000, 54667, 53333, 52000, 50667, 49333, 48000, 46667,
45333, 44000, 42667, 41333, 40000, 38667, 37333, 36000,
34667, 33333, 32000, 30667, 29333, 28000
V.92 downstream
V92
56000, 54667, 53333, 52000, 50667, 49333, 48000, 46667,
45333, 44000, 42667, 41333, 40000, 38667, 37333, 36000,
34667, 33333, 32000, 30667, 29333, 28000
V.92 upstream
V92
48000, 46667, 45333, 44000, 42667, 41333, 40000, 38667,
37333, 36000, 34667, 33333, 32000, 30667, 29333, 28000,
26667, 25333, 24000
2.3.8 Automode
Automode detection can be enabled by the +MS command to allow the modem to
connect to a remote modem in accordance with draft PN-3320 for V.34 (Table 2-1).
2.4 Data Mode
Data mode exists when a telephone line connection has been established between
modems and all handshaking has been completed.
2.4.1 Speed Buffering (Normal Mode)
Speed buffering allows a DTE to send data to, and receive data from, a modem at a speed
different than the line speed. The modem supports speed buffering at all line speeds.
2.4.2 Flow Control
DTE-to-Modem Flow Control. If the modem-to-line speed is less than the DTE-to-
modem speed, the modem supports XOFF/XON or RTS/CTS flow control with the DTE
to ensure data integrity.
CX86500 SCXV.xx Modem Data Sheet
2-4 Conexant 102287H
2.4.3 Escape Sequence Detection
The +++ escape sequence can be used to return control to the command mode from the
data mode. Escape sequence detection is disabled by an S2 Register value greater than
127.
2.4.4 BREAK Detection
The modem can detect a BREAK signal from either the DTE or the remote modem. The
\Kn command determines the modem response to a received BREAK signal.
2.4.5 Telephone Line Monitoring
GSTN Cleardown (V.92, V.90, V.34, V.32 bis, V.32). Upon receiving GSTN
Cleardown from the remote modem in a non-error correcting mode, the modem cleanly
terminates the call.
Loss of Carrier (V.22 bis and Below). If carrier is lost for a time greater than specified
by the S10 register, the modem disconnects.
2.4.6 Fall Forward/Fallback (V.92/V.90/V.34/V.32 bis/V.32)
During initial handshake, the modem will fallback to the optimal line connection within
V.92/V.90/V.34/V.32 bis/V.32 mode depending upon signal quality if automode is
enabled by the +MS or N1 command.
When connected in V.92/V.90/V.34/V.32 bis/V.32 mode, the modem will fall forward or
fallback to the optimal line speed within the current modulation depending upon signal
quality if fall forward/fallback is enabled by the %E2 command.
2.4.7 Retrain
The modem may lose synchronization with the received line signal under poor or
changing line conditions. If this occurs, retraining may be initiated to attempt recovery
depending on the type of connection.
The modem initiates a retrain if line quality becomes unacceptable if enabled by the %E
command. The modem continues to retrain until an acceptable connection is achieved, or
until 30 seconds elapse resulting in line disconnect.
2.4.8 Programmable Inactivity Timer
The modem disconnects from the line if data is not sent or received for a specified length
of time. In normal or error-correction mode, this inactivity timer is reset when data is
received from either the DTE or from the line. This timer can be set to a value between 0
and 255 seconds by using register S30. A value of 0 disables the inactivity timer.
2.4.9 DTE Signal Monitoring (Serial DTE Interface Only)
DTR#. When DTR# is asserted, the modem responds in accordance with the &Dn and
&Qn commands.
RTS#. RTS# is used for flow control if enabled by the &K command in normal or error-
correction mode.
CX86500 SCXV.xx Modem Data Sheet
102287H Conexant 2-5
2.4.10 Call Progress Speaker Interface
A digital speaker output (DSPKOUT) is supported. DSPKOUT is a square wave output
in Data mode used for call progress or carrier monitoring. This output can be optionally
connected to a low-cost on-board speaker, e.g., a sounducer, or to an analog speaker
circuit.
2.4.11 Serial EEPROM Interface
The 38-pin TSSOP supports a 2-line serial interface to an optional serial EEPROM.
The EEPROM can hold information such as firmware customization, and country code
parameters. Data stored in EEPROM takes precedence over the factory default settings.
A serial EEPROM is required only if additional storage is required for more country
profiles or customized firmware code.
The EEPROM size can range from 2 Kb (256 x 8) to 256 Kb (32K x 8). A 2 Kb
EEPROM must be 100 kHz or 400 kHz; higher capacity EEPROMs must be 400 kHz.
2.5 V.92 Features
Modem-on-Hold, quick connect, and PCM upstream are only available when connecting
in V.92 data mode. V.92 features are only available when the server called is a V.92
server that supports that particular feature.
2.5.1 Modem-on-Hold
The Modem-on-Hold (MOH) function (V.92 models only) enables the modem to place
an Internet data connection on hold while using the same line to accept an incoming or
place an outgoing voice call. This feature is available only with a connection to a server
supporting MOH. MOH can be executed through either of two methods:
One method is to enable MOH through the +PMH command. With Call Waiting
Detection (+PCW command) enabled, an incoming call can be detected while on-
line. Using a string of commands, the modem negotiates with the server to place the
data connection on hold while the line is released so that it can be used to conduct a
voice call. Once the voice call is completed, the modem can quickly renegotiate with
the server back to the original data call.
An alternative method is to use communications software that makes use of the
Conexant Modem-on-Hold drivers. Using this method, the software can detect an
incoming call, place the data connection on hold, and switch back to a data
connection.
2.5.2 Quick Connect
The quick connect function (V.92 models only) enables the modem to shorten the
connect time of subsequent calls to a server supporting quick connect. The quick connect
feature is supported by the +PQC command.
2.5.3 PCM Upstream
PCM upstream boosts the upstream data rates between the user and ISP to reduce upload
times for large files and email attachments. A maximum of 48 kbps upstream rate is
CX86500 SCXV.xx Modem Data Sheet
2-6 Conexant 102287H
supported with PCM upstream enabled, in contrast to a maximum of 32.2 kbps upstream
rate with PCM upstream not enabled. PCM upstream is supported by the +PCM
command. PCM upstream is disabled by default.
2.6 Error Correction and Data Compression
2.6.1 V.42 Error Correction
V.42 supports two methods of error correction: LAPM and, as a fallback, MNP 4. The
modem provides a detection and negotiation technique for determining and establishing
the best method of error correction between two modems.
2.6.2 MNP 2-4 Error Correction
MNP 2-4 is a data link protocol that uses error correction algorithms to ensure data
integrity. Supporting stream mode, the modem sends data frames in varying lengths
depending on the amount of time between characters coming from the DTE.
2.6.3 V.44 Data Compression
V.44 data compression encodes pages and files associated with Web pages more
efficiently than V.42 bis. These files include WEB pages, graphics and image files, and
document files. V.44 can provide an effective data throughput rate up to DTE rate for a
56-kbps connection. The improved performance amount varies both with the actual
format and with the content of individual pages and files.
2.6.4 V.42 bis Data Compression
V.42 bis data compression mode, enabled by the %Cn command or S46 register, operates
when a LAPM connection is established.
The V.42 bis data compression employs a “string learning” algorithm in which a string of
characters from the DTE is encoded as a fixed length codeword and stored in a
dictionary. The dictionary is dynamically updated during normal operation.
CX86500 SCXV.xx Modem Data Sheet
102287H Conexant 2-7
2.6.5 MNP 5 Data Compression
MNP 5 data compression mode, enabled by the %Cn command, operates during an MNP
connection.
In MNP 5, the modem increases its throughput by compressing data into tokens before
transmitting it to the remote modem, and by decompressing encoded received data before
sending it to the DTE.
2.7 Voice Pass-Through Mode
Voice Pass-Through Mode supports data transfer sampled at 8 KHz. Mu-Law and A-Law
are supported both in serial and parallel modes. 14-bit PCM is supported in parallel mode
only.
For 14-bit PCM, data is transmitted in 8-bit words. Bit 0 of each 8-bit word is used to
identify the most significant byte and the least significant byte (see Section 3.7.2.3).
When transmitting data, bit 0 must be set to 0 identify the most significant byte B(15:8)
or it must be set to 1 to identify the least significant byte B(7:0). During transmission, the
most significant byte must precede the least significant byte.
The 14-bit PCM data receive format is the same as the transmit format. During reception,
the most significant byte precedes the least significant byte. Bit 0 is set to 0 to identify the
most significant byte or it is set to 1 to identify the least significant byte.
2.8 Telephony Extensions
The following telephony extension features are supported and are typically implemented
in designs for set-top box applications to enhance end-user experience:
Line-in-use detection
Extension pick-up detection
Remote hang-up detection
The telephony extension features are enabled through the -STE command. The -TTE
command can be used to adjust the voltage thresholds for the telephony extension
features.
2.8.1 Line-in-Use Detection
The line-in-use detection feature can stop the modem from disturbing the phone line
when the line is already being used. When an attempt is made to dial using ATDT and the
phone line is in use, the modem will not go off hook and will respond with the message
“LINE IN USE”.
2.8.2 Extension Pick-up Detection
The extension pick-up detection feature (also commonly referred as PPD or Parallel
phone detection) allows the modem to detect when another telephony device (i.e., fax
machine, phone, satellite/cable box) is attempting to use the phone line. When an
extension pick-up has been detected, the modem will go on-hook and respond with the
message “OFF-HOOK INTRUSION”.
CX86500 SCXV.xx Modem Data Sheet
2-8 Conexant 102287H
This feature can be used to quickly drop a modem connection in the event when a user
picks up an extension phone line. For example, this feature allows set top boxes with an
integrated SCXV.xx modem to give normal voice users the highest priority over the
telephone line.
2.8.3 Remote Hang-up Detection
The remote hang-up detection feature will cause the modem to go back on-hook and
respond with the message “LINE REVERSAL DETECTED” during a data connection
when the remote modem is disconnected for abnormal termination reasons (remote phone
line unplugged, remote server/modem shutdown).
2.9 Point-of-Sales Support
Point-of-Sales (POS) terminals usually need to exchange a small amount of data in the
shortest amount of time. Low speed modulations such as Bell212A or V.22 are still
mainly used in POS applications. Additionally, new non-standard sequences have been
developed to better support POS applications.
Industry standard and shortened answer tone B103 and V.21 are supported, as well as
FastPOS (V.29) and V.22 FastConnect. POS terminal modulations are supported by the
$F command.
2.10 Tone Detectors
The modem is equipped with three tone detectors with separate signal paths from the
main received signal path thus enabling tone detection to be independent of the
configuration status.
2.11 Call Waiting Tone Detection
Call Waiting tones can be detected when in V.92, V.90, V.34, and V.32bis data modes.
2.12 Caller ID
Both Type I Caller ID (On-Hook Caller ID) and Type II Caller ID (Call Waiting Caller
ID) are supported for U.S. and many other countries (see Section 2.13). Both types of
Caller ID are enabled/disabled using the +VCID command. Call Waiting Tone detection
must be enabled using the +PCW command to detect and decode Call Waiting Caller ID.
When enabled, caller ID information (date, time, caller code, and name) can be passed to
the DTE in formatted or unformatted form. Inquiry support allows the current caller ID
mode and mode capabilities of the modem to be retrieved from the modem.
Type II Caller ID (Call Waiting Caller ID) detection operates only during data mode in
V.92, V.90, V.34, V.32bis, or V.32.
CX86500 SCXV.xx Modem Data Sheet
102287H Conexant 2-9
2.13 Worldwide Country Support
Internal modem firmware supports 63 country profiles (see Table 1-2). These country
profiles include the following country-dependent parameters:
Dial tone detection levels and frequency ranges.
DTMF dialing parameters: Transmit output level, DTMF signal duration, and DTMF
interdigit interval.
Pulse dialing parameters: Make/break times, set/clear times, and dial codes are
programmable.
Ring detection frequency range.
Type I and Type II Caller ID detection are supported for many countries. Contact
your local Conexant sales office for additional country support.
Blind dialing enabled/disable.
Carrier transmit level. The maximum, minimum, and default values can be defined to
match specific country and DAA requirements.
Calling tone is generated in accordance with V.25. Calling tone may be toggled
(enabled/disabled) by inclusion of a “^” character in a dial string. It may also be
disabled.
Frequency and cadence of tones for busy, ringback, congested, warble, dial tone 1,
and dial tone 2.
Answer tone detection period.
Blacklist parameters. The modem can operate in accordance with requirements of
individual countries to prevent misuse of the network by limiting repeated calls to
the same number when previous call attempts have failed. Call failure can be
detected for reasons such as no dial tone, number busy, no answer, no ringback
detected, voice (rather than modem) detected, and key abort (dial attempt aborted by
user). Actions resulting from such failures can include specification of minimum
inter-call delay, extended delay between calls, and maximum numbers of retries
before the number is permanently forbidden ("blacklisted").
The country profiles may be altered or customized by modifying the country-dependent
parameters. Additional profiles may also be included. Additional and modified country
profiles are supported by internal SRAM.
Please contact an FAE at the local Conexant sales office for additional and modified
country profile support.
2.14 Diagnostics
Diagnostics are performed in response to test commands.
Analog Loopback (&T1 Command). Data from the local DTE is sent to the modem,
which loops the data back to the local DTE.
DMTF Generation (%TT0 Command). Continuous DTMF tones are generated by the
DSP and output through the DAA.
Tone Generation (%TT3 Command). Continuous tones are generated by the DSP and
output through the DAA.
CX86500 SCXV.xx Modem Data Sheet
2-10 Conexant 102287H
2.15 Low Power Modes
The modem enters a low power mode when no line connection exists and no host activity
occurs for the period of time specified in the S24 register. The modem supports three low
power modes: Idle Mode, Sleep Mode, and Stop Mode. The low power mode entered
depends on the setting of the –SLP command.
In Idle Mode, the CPU and LSD run at a low frequency. The modem can detect and
qualify ring signals and process AT commands. The modem returns to normal mode upon
receiving an AT command or receiving a qualified ring.
In Sleep Mode, the CPU and LSD run at a lower frequency than Idle Mode. The modem
can detect and qualify ring signals but cannot process AT commands. The modem can be
awakened by the host sending a single (any) character (typically followed by an AT
command), or by the modem receiving a qualified ring.
In Stop Mode, the CPU runs at the same low frequency as the Sleep Mode, however, the
LSD is turned off. The modem cannot process AT commands and cannot detect and
qualify ring signals. The modem can be awakened by the host sending a single (any)
character (typically followed by an AT command).
CX86500 SCXV.xx Modem Data Sheet
102287H Conexant 3-1
3. Hardware Interface
3.1 CX86500 Hardware 28-Pin TSSOP with Serial Interface
3.1.1 CX86500 Modem 28-Pin TSSOP with Serial Interface Signal Summary
3.1.1.1 LSD Interface (Through DIB)
The DIB interface signals are:
Clock and Power Positive (PWRCLKP); output
Clock and Power Negative (PWRCLKN); output
Data Positive (DIB_DATAP); input/output
Data Negative (DIB_DATAN); input/output
3.1.1.2 Call Progress Speaker Interface
The call progress speaker interface signal is:
Digital speaker output (DSPKOUT); output
3.1.1.3 Serial DTE Interface and Indicator Outputs
The supported DTE interface signals are:
Serial Transmit Data input (TXD#)
Serial Receive Data output line (RXD#)
Clear to Send output (CTS#)
Received Line Signal Detector (RLSD#)
Ring Indicator (RI#)
Data Terminal Ready control input (DTR#)
Request to Send control input (RTS#)
Additional clock signals provided for synchronous mode are:
Receive Data Clock (RXCLK#)
Transmit Data Clock (TXCLK#)
CX86500 SCXV.xx Modem Data Sheet
3-2 Conexant 102287H
3.1.2 CX86500 Modem 28-Pin TSSOP with Serial Interface Pin Assignments
and Signal Definitions
CX86500 Modem 28-pin TSSOP hardware interface signals are shown by major
interface in Figure 3-1, are shown by pin number in Figure 3-2, and are listed by pin
number in Table 3-1.
CX86500 Modem hardware interface signals are defined in Table 3-2.
Figure 3-1. CX86500 Modem 28-Pin TSSOP with Serial Interface Hardware Signals
XTLI
XTLO
TXD#
RXD#
CTS#
RI#
DTR#
RTS#
RXCLK#
TXCLK#
RLSD#
SCLKSEL#
RESET#
LPO
1
2
5
4
11
18
12
10
6
8
17
15
3
23
SERIAL HOST
INTERFACE
PWRCLKP
PWRCLKN
DIB_DATAP
DIB_DATAN
DSPKOUT
VDD_CORE
VDD
VDD
GND
GND
RESERVED
RESERVED
RESERVED
RESERVED
26
27
20
21
28
24
7
22
9
25
13
14
16
19
102287_002
CX86500
Modem
28-Pin TSSOP
Serial
Interface
DIGITAL ISOLATION
BARRIER (DIB)
RESET CIRCUIT
SPEAKER CIRCUIT
+3.3V 240K
+3.3V
28.224 OR 27.000 MHZ
CRYSTAL OR CLOCK OSCILLATOR
FREQUENCY SELECT
CIRCUIT
CX86500 SCXV.xx Modem Data Sheet
102287H Conexant 3-3
Figure 3-2. CX86500 Modem 28-Pin TSSOP with Serial Interface Pin Signals
102287_003
1
2
3
4
5
6
7
8
9
10
11
12
13
14
XTLI
XTLO
RESET#
RXD#
TXD#
RXCLK#
VDD
TXCLK#
GND
RTS#
CTS#
DTR#
RESERVED
RESERVED
DSPKOUT
PWRCLKN
PWRCLKP
GND
VDD_CORE
LPO
VDD
DIB_DATAN
DIB_DATAP
RESERVED
RI#
RLSD#
RESERVED
SCLKSEL#
Top View
28
27
26
25
24
23
22
21
20
19
18
17
16
15
CX86500
28-Pin TSSOP
Table 3-1. CX86500 Modem 28-Pin TSSOP with Serial Interface Pin Signals
Pin No.
Signal Name
Pin No.
Signal Name
1
XTLI
15
SCLKSEL#
2
XTLO
16
RESERVED
3
RESET#
17
RLSD#
4
RXD#
18
RI#
5
TXD#
19
RESERVED
6
RXCLK#
20
DIB_DATAP
7
VDD
21
DIB_DATAN
8
TXCLK#
22
VDD
9
GND
23
LPO
10
RTS#
24
VDD_CORE
11
CTS#
25
GND
12
DTR#
26
PWRCLKP
13
RESERVED
27
PWRCLKN
14
RESERVED
28
DSPKOUT
CX86500 SCXV.xx Modem Data Sheet
3-4 Conexant 102287H
Table 3-2. CX86500 Modem 28-Pin TSSOP with Serial Interface Hardware Signal Definitions
Label
Pin
I/O
I/O Type
Signal Name/Description
System
XTLI
1
I
Ix
Crystal Oscillator Input. Connect XTLI to a 28.224 MHz or 27.000 MHz
crystal or clock oscillator circuit. (See SCLKSEL# pin description.)
XTLO
2
O
Ox
Crystal Oscillator Output If XTLI is connected to a 28.224 MHz or
27.000 MHz crystal circuit, also connect XTLO to the crystal circuit; if
XTLI is connected to a 28.224 MHz or 27.000 MHz clock oscillator
circuit, leave XTLO open.
SCLKSEL#
15
I
Ipu/O2
Clock Frequency Select. Clock frequency is selected by SCLKSEL#
during reset processing. Leave open for 27.000 MHz operation; connect
pin to digital ground (GND) for 28.224 MHz operation.
RESET#
3
I
Ipu/O2
Reset. The active low RESET# input resets the modem logic and clears
the internal SRAM.
RESET# low holds the modem in the reset state; RESET# going high
releases the modem from the reset state. After application of VDD,
RESET# must be held low for at least 15 ms after the VDD power
reaches operating range. The modem device set is ready to use 25 ms
after the low-to-high transition of RESET#.
VDD_CORE
24
O
PWR
Core Supply Voltage. Internal +1.8 V core voltage for decoupling. Do
not connect this pin to an external +1.8 V power supply.
VDD
7, 22
I
PWR
Digital Supply Voltage. Connect to +3.3V.
GND
9, 25
I
GND
Digital Ground. Connect to digital ground (GND).
LPO
23
I
Rx
Low Power Oscillator. Connect to +3.3V through 240 K.
Speaker Interface
DSPKOUT
28
O
Ipd/O2
Modem Speaker Digital Output. The DSPKOUT digital output reflects
the received analog input signal digitized to TTL high or low level by an
internal comparator.
DIB Interface
PWRCLKP
26
O
Odpc
Clock and Power Positive. Provides clock and power to the LSD.
Connect to DIB transformer primary winding non-dotted terminal.
PWRCLKN
27
O
Odpc
Clock and Power Negative. Provides clock and power to the LSD.
Connect to DIB transformer primary winding dotted terminal.
DIB_DATAP
20
I/O
Idd/Odd
Data Positive. Transfers data, control, and status information between
the CX86500 and the LSD. Connect to LSD through DIB data positive
channel components.
DIB_DATAN
21
I/O
Idd/Odd
Data Negative. Transfers data, control, and status information between
the CX86500 and the LSD. Connect to LSD through DIB data negative
channel components.
CX86500 SCXV.xx Modem Data Sheet
102287H Conexant 3-5
Table 3-2. CX86500 Modem 28-Pin TSSOP with Serial Interface Hardware Signal Definitions (Continued)
Label
Pin
I/O
I/O Type
Signal Name/Description
V.24 (EIA/TIA-232-E) DTE Serial Interface
TXD#
5
I
Ipu/O2
Transmitted Data (EIA BA/ITU-T CT103). The DTE uses the TXD# line
to send data to the modem for transmission over the telephone line or to
transmit commands to the modem.
RXD#
4
O
Ipu/O2
Received Data (EIA BB/ITU-T CT104). The modem uses the RXD# line
to send data received from the telephone line to the DTE and to send
modem responses to the DTE. During command mode, RXD# data
represents the modem responses to the DTE.
CTS#
11
O
Ipu/O2
Clear To Send (EIA CB/ITU-T CT106). CTS# output ON (low) indicates
that the modem is ready to accept data from the DTE. In error correction
or normal mode, CTS# is always ON (low) unless RTS/CTS flow control
is selected by the &Kn command.
RLSD#
17
O
Ipu/O2
Received Line Signal Detector (EIA CF/ITU-T CT109). During normal
operation, when AT&C0 command is not in effect, RLSD#/CLKSEL#
output is ON when a carrier is detected on the telephone line or OFF
when carrier is not detected.
RI#
18
O
Ipu/O2
Ring Indicator (EIA CE/ITU-T CT125). RI# output ON (low) indicates
the presence of an ON segment of a ring signal on the telephone line.
DTR#
12
I
Ipu/O2
Data Terminal Ready (EIA CD/ITU-T CT108). The DTR# input is turned
ON (low) by the DTE when the DTE is ready to transmit or receive data.
DTR# ON prepares the modem to be connected to the telephone line,
and maintains the connection established by the DTE (manual
answering) or internally (automatic answering). DTR# OFF places the
modem in the disconnect state under control of the &Dn and &Qn
commands.
RTS#
10
I
Ipu/O2
Request To Send (EIA CA/ITU-T CT105). RTS# input ON (low)
indicates that the DTE is ready to send data to the modem. In the
command state, the modem ignores RTS#.
The modem ignores RTS# unless RTS/CTS flow control is selected by
the &Kn command.
RXCLK#
6
O
Ipu/O2
Receive Data Clock. RXCLK# is output in synchronous mode. The
RXCLK# frequency is the data rate (±0.01%) with a duty cycle of 50±1%.
Leave open if not used.
TXCLK#
8
O
Ipu/O2
Transmit Data Clock. TXCLK# is output in synchronous mode. The
TXCLK frequency is the data rate (±0.01%) with a duty cycle of 50±1%.
Leave open if not used.
RESERVED
RESERVED
19
Reserved. Connect to digital ground (GND).
RESERVED
13, 14, 16
Reserved. Leave open or connect to digital ground (GND).
Note:
I/O Types: See Table 3-7.
CX86500 SCXV.xx Modem Data Sheet
3-6 Conexant 102287H
3.2 CX86500 Modem 38-Pin TSSOP with Serial or Parallel
Interface Hardware Pins and Signals
3.2.1 CX86500 Modem 38-Pin TSSOP with Serial Interface Signal Summary
3.2.1.1 LSD Interface (Through DIB)
The DIB interface signals are:
Clock and Power Positive (PWRCLKP); output
Clock and Power Negative (PWRCLKN); output
Data Positive (DIB_DATAP); input/output
Data Negative (DIB_DATAN); input/output
3.2.1.2 Call Progress Speaker Interface
The call progress speaker interface signal is:
Digital speaker output (DSPKOUT); output
3.2.1.3 Serial EEPROM Interface
The 2-line serial interface signals to an optional serial EEPROM are:
Bidirectional Data input/output (NVMDATA)
Clock output (NVMCLK)
3.2.1.4 Serial DTE Interface and Indicator Outputs
The supported DTE interface signals are:
Serial Transmit Data input (TXD#)
Serial Receive Data output line (RXD#)
Clear to Send output (CTS#)
Data Set Ready output (DSR#)
Received Line Signal Detector (RLSD#)
Ring Indicator (RI#)
Data Terminal Ready control input (DTR#)
Request to Send control input (RTS#)
Additional clock signals provided for synchronous mode are:
Receive Data Clock (RXCLK#)
Transmit Data Clock (TXCLK#)
CX86500 SCXV.xx Modem Data Sheet
102287H Conexant 3-7
3.2.2 CX86500 Modem 38-Pin TSSOP with Serial Interface Pin Assignments
and Signal Definitions
CX86500 Modem 38-pin TSSOP hardware interface signals are shown by major
interface in Figure 3-3 are shown by pin number in Figure 3-4, and are listed by pin
number in Table 3-3.
CX86500 Modem hardware interface signals are defined in Table 3-4.
Figure 3-3. CX86500 Modem 38-Pin TSSOP with Serial Interface Hardware Signals
XTLI
XTLO
TXD#
RXD#
CTS#
RI#
DTR#
RTS#
DSR#
RXCLK#
TXCLK#
RLSD#/CLKSEL#
SCLKSEL#
RESET#
LPO
3
4
7
6
16
23
17
15
27
8
12
22
20
5
31
PWRCLKP
PWRCLKN
DIB_DATAP
DIB_DATAN
DSPKOUT
NVMDATA
NVMCLK/PARIF
VDD_CORE
VDD
VDD
VDD
GND
GND
GND
GND
NC
NC
RESERVED
RESERVED
RESERVED
RESERVED
RESERVED
RESERVED
34
35
25
26
36
29
13
32
9
10
30
1
14
33
38
2
37
11
18
19
21
28
24
102287_004
CX86500
Modem
38-Pin TSSOP
Serial
Interface
DIGITAL ISOLATION
BARRIER (DIB)
RESET CIRCUIT
SPEAKER CIRCUIT
+3.3V 240K
+3.3V
NC
SERIAL EEPROM
28.224 OR 27.000 MHZ
CRYSTAL OR CLOCK OSCILLATOR
SERIAL HOST
INTERFACE
FREQUENCY SELECT
CIRCUIT
10K
CX86500 SCXV.xx Modem Data Sheet
3-8 Conexant 102287H
Figure 3-4. CX86500 Modem 38-Pin TSSOP with Serial Interface Pin Signals
102287_005
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
GND
NC
XTLI
XTLO
RESET#
RXD#
TXD#
RXCLK#
VDD
VDD
RESERVED
TXCLK#
NVMCLK/PARIF
GND
RTS#
CTS#
DTR#
RESERVED
RESERVED
GND
NC
DSPKOUT
PWRCLKN
PWRCLKP
GND
VDD_CORE
LPO
VDD
NVMDATA
RESERVED
DSR#
DIB_DATAN
DIB_DATAP
RESERVED
RI#
RLSD#
RESERVED
SCLKSEL#
Top View
38
37
36
35
34
33
32
31
30
29
28
27
26
25
24
23
22
21
20
CX86500
38-Pin TSSOP
Table 3-3. CX86500 Modem 38-Pin TSSOP with Serial Interface Pin Signals
Pin No.
Signal Name
Pin No.
Signal Name
1
GND
20
SCLKSEL#
2
NC
21
RESERVED
3
XTLI
22
RLSD#
4
XTLO
23
RI#
5
RESET#
24
RESERVED
6
RXD#
25
DIB_DATAP
7
TXD#
26
DIB_DATAN
8
RXCLK#
27
DSR#
9
VDD
28
RESERVED
10
VDD
29
NVMDATA
11
RESERVED
30
VDD
12
TXCLK#
31
LPO
13
NVMCLK/PARIF
32
VDD_CORE
14
GND
33
GND
15
RTS#
34
PWRCLKP
16
CTS#
35
PWRCLKN
17
DTR#
36
DSPKOUT
18
RESERVED
37
NC
19
RESERVED
38
GND
CX86500 SCXV.xx Modem Data Sheet
102287H Conexant 3-9
Table 3-4. CX86500 Modem 38-Pin TSSOP with Serial Interface Hardware Signal Definitions
Label
Pin
I/O
I/O Type
Signal Name/Description
System
XTLI
3
I
Ix
Crystal Oscillator Input. Connect XTLI to a 28.224 MHz or 27.000 MHz
crystal or clock oscillator circuit. (See SCLKSEL# pin description.)
XTLO
4
O
Ox
Crystal Oscillator Output If XTLI is connected to a 28.224 MHz or
27.000 MHz crystal circuit, also connect XTLO to the crystal circuit; if
XTLI is connected to a 28.224 MHz or 27.000 MHz clock oscillator
circuit, leave XTLO open.
SCLKSEL#
20
I
Ipu/O2
Clock Frequency Select. Clock frequency is selected by SCLKSEL#
during reset processing. Leave open for 27.000 MHz operation; connect
pin to digital ground (GND) for 28.224 MHz operation.
RESET#
5
I
Ipu/O2
Reset. The active low RESET# input resets the modem logic and clears
the internal SRAM.
RESET# low holds the modem in the reset state; RESET# going high
releases the modem from the reset state. After application of VDD,
RESET# must be held low for at least 15 ms after the VDD power
reaches operating range. The modem device set is ready to use 25 ms
after the low-to-high transition of RESET#.
VDD_CORE
32
O
PWR
Core Supply Voltage. Internal +1.8 V core voltage for decoupling. Do
not connect this pin to an external +1.8 V power supply.
VDD
9, 10, 30
I
PWR
Digital Supply Voltage. Connect to +3.3V.
GND
1, 14, 33,
38
I
GND
Digital Ground. Connect to digital ground (GND).
LPO
31
I
Rx
Low Power Oscillator. Connect to +3.3V through 240 K.
Speaker Interface
DSPKOUT
36
O
Ipd/O2
Modem Speaker Digital Output. The DSPKOUT digital output reflects
the received analog input signal digitized to TTL high or low level by an
internal comparator.
DIB Interface
PWRCLKP
34
O
Odpc
Clock and Power Positive. Provides clock and power to the LSD.
Connect to DIB transformer primary winding non-dotted terminal.
PWRCLKN
35
O
Odpc
Clock and Power Negative. Provides clock and power to the LSD.
Connect to DIB transformer primary winding dotted terminal.
DIB_DATAP
25
I/O
Idd/Odd
Data Positive. Transfers data, control, and status information between
the CX86500 and the LSD. Connect to LSD through DIB data positive
channel components.
DIB_DATAN
26
I/O
Idd/Odd
Data Negative. Transfers data, control, and status information between
the CX86500 and the LSD. Connect to LSD through DIB data negative
channel components.
NVRAM Interface
NVMCLK/PARIF
13
I/O
Ipu/O2
NVRAM Clock. During normal operation, NVMCLK/PARIF output high
enables the EEPROM. Connect to EEPROM SCL pin.
Parallel/Serial Interface Select. During reset processing: parallel host
interface is selected by NVMCLK/PARIF high (by internal pullup when no
external pullup is connected to the pin); serial host interface is selected
by NVMCLK/PARIF low (pin connected to GND through a 10 K
pulldown resistor).
NVMDATA
29
I/O
Ipu/O2
NVRAM Data. The NVMDATA pin supplies a serial data interface to the
EEPROM. Connect to EEPROM SDA pin and to +3.3V through 10 K.
CX86500 SCXV.xx Modem Data Sheet
3-10 Conexant 102287H
Table 3-4. CX86500 Modem 38-Pin TSSOP with Serial Interface Hardware Signal Definitions (Continued)
Label
Pin
I/O
I/O Type
Signal Name/Description
V.24 (EIA/TIA-232-E) DTE Serial Interface
TXD#
7
I
Ipu/O2
Transmitted Data (EIA BA/ITU-T CT103). The DTE uses the TXD# line
to send data to the modem for transmission over the telephone line or to
transmit commands to the modem.
RXD#
6
O
Ipu/O2
Received Data (EIA BB/ITU-T CT104). The modem uses the RXD# line
to send data received from the telephone line to the DTE and to send
modem responses to the DTE. During command mode, RXD# data
represents the modem responses to the DTE.
CTS#
16
O
Ipu/O2
Clear To Send (EIA CB/ITU-T CT106). CTS# output ON (low) indicates
that the modem is ready to accept data from the DTE. In error correction
or normal mode, CTS# is always ON (low) unless RTS/CTS flow control
is selected by the &Kn command.
RLSD#
22
O
Ipu/O2
Received Line Signal Detector (EIA CF/ITU-T CT109). During normal
operation, when AT&C0 command is not in effect, RLSD#/CLKSEL#
output is ON when a carrier is detected on the telephone line or OFF
when carrier is not detected.
Clock Frequency Select. During reset processing: 28.224 MHz
operation is selected by RLSD#/CLKSEL# high (by internal pullup when
no external pullup is connected to the pin); 27.000 MHz operation is
selected by RLSD#/CLKSEL# low (pin connected to GND through a
10 K pulldown resistor).
RI#
23
O
Ipu/O2
Ring Indicator (EIA CE/ITU-T CT125). RI# output ON (low) indicates the
presence of an ON segment of a ring signal on the telephone line.
DTR#
17
I
Ipu/O2
Data Terminal Ready (EIA CD/ITU-T CT108). The DTR# input is turned
ON (low) by the DTE when the DTE is ready to transmit or receive data.
DTR# ON prepares the modem to be connected to the telephone line,
and maintains the connection established by the DTE (manual
answering) or internally (automatic answering). DTR# OFF places the
modem in the disconnect state under control of the &Dn and &Qn
commands.
RTS#
15
I
Ipu/O2
Request To Send (EIA CA/ITU-T CT105). RTS# input ON (low)
indicates that the DTE is ready to send data to the modem. In the
command state, the modem ignores RTS#.
The modem ignores RTS# unless RTS/CTS flow control is selected by
the &Kn command.
DSR#
27
O
Ipu/O2
Data Set Ready (EIA CC/ITU-T CT107). DSR# indicates modem status
to the DTE. DSR# OFF (high) indicates that the DTE is to disregard all
signals appearing on the interchange circuits except Ring Indicator (RI#).
DSR# output is controlled by the AT&Sn command.
RXCLK#
8
O
Ipu/O2
Receive Data Clock. RXCLK# is output in synchronous mode. The
RXCLK# frequency is the data rate (±0.01%) with a duty cycle of 50±1%.
Leave open if not used.
TXCLK#
12
O
Ipu/O2
Transmit Data Clock. TXCLK# is output in synchronous mode. The
TXCLK frequency is the data rate (±0.01%) with a duty cycle of 50±1%.
Leave open if not used.
Reserved
RESERVED
24
Reserved. Connect to digital ground (GND).
RESERVED
11, 18, 19,
21, 28
Reserved. Leave open or connect to digital ground (GND).
No Connect
NC
2, 37
No Internal Connection. Leave open.
Note:
I/O Types: See Table 3-7.
CX86500 SCXV.xx Modem Data Sheet
102287H Conexant 3-11
3.2.3 CX86500 Modem 38-Pin TSSOP with Parallel Interface Signal Summary
3.2.3.1 LSD Interface (Through DIB)
The DIB interface signals are:
Clock and Power Positive (PWRCLKP); output
Clock and Power Negative (PWRCLKN); output
Data Positive (DIB_DATAP); input/output
Data Negative (DIB_DATAN); input/output
3.2.3.2 Call Progress Speaker Interface
The call progress speaker interface signal is:
Digital speaker output (DSPKOUT); output
3.2.3.3 Serial EEPROM Interface
The 2-line serial interface signals to an optional serial EEPROM are:
Bidirectional Data input/output (NVMDATA)
Clock output (NVMCLK)
3.2.3.4 Parallel Host Bus Interface
The parallel host interface signals are:
Host Reset control input line (RESET#)
Host Chip Select control input (HCS#)
Host Read control input (HRD#) and Host Write control input (HWT#)
Host Interrupt output line (HINT)
Three Host Address input lines (HA0-HA2)
Eight Host Data lines (HD0-HD7)
CX86500 SCXV.xx Modem Data Sheet
3-12 Conexant 102287H
3.2.4 CX86500 Modem 38-Pin TSSOP with Parallel Interface Pin Assignments
and Signal Definitions
CX86500 Modem 38-pin TSSOP hardware interface signals are shown by major
interface in Figure 3-5 are shown by pin number in Figure 3-6, and are listed by pin
number in Table 3-5.
CX86500 Modem hardware interface signals are defined in Table 3-6.
Figure 3-5. CX86500 Modem 38-Pin TSSOP with Parallel Interface Hardware Signals
XTLI
XTLO
HA0
HA1
HA2
HD0
HD1
HD2
HD3
HD4
HD5
HD6
HD7
HCS#
HRD#
HWT#
HINT
PCLKSEL#
RESET#
LPO
3
4
6
7
8
12
15
16
17
22
23
27
28
18
21
20
19
11
5
31
PARALLEL HOST
INTERFACE
PWRCLKP
PWRCLKN
DIB_DATAP
DIB_DATAN
DSPKOUT
NVMDATA
NVMCLK/PARIF
VDD_CORE
VDD
VDD
VDD
GND
GND
GND
GND
NC
NC
RESERVED
34
35
25
26
36
29
13
32
9
10
30
1
14
33
38
2
37
24
102287_006
CX86500
Modem
38-Pin TSSOP
Parallel
Interface
DIGITAL ISOLATION
BARRIER (DIB)
RESET CIRCUIT
SPEAKER CIRCUIT
+3.3V 240K
+3.3V
NC
SERIAL EEPROM
28.224 MHZ OR 27.000 MHZ
CRYSTAL OR CLOCK OSCILLATOR
FREQUENCY SELECT
CIRCUIT
CX86500 SCXV.xx Modem Data Sheet
102287H Conexant 3-13
Figure 3-6. CX86500 Modem 38-Pin TSSOP with Parallel Interface Pin Signals
102287_007
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
GND
NC
XTLI
XTLO
RESET#
HA0
HA1
HA2
VDD
VDD
PCLKSEL#
HD0
NVMCLK/PARIF
GND
HD1
HD2
HD3
HCS#
HINT
GND
NC
DSPKOUT
PWRCLKN
PWRCLKP
GND
VDD_CORE
LPO
VDD
NVMDATA
HD7
HD6
DIB_DATAN
DIB_DATAP
RESERVED
HD5
HD4
HRD#
HWT#
Top View
38
37
36
35
34
33
32
31
30
29
28
27
26
25
24
23
22
21
20
CX86500
38-Pin TSSOP
Table 3-5. CX86500 Modem 38-Pin TSSOP with Parallel Interface Pin Signals
Pin No.
Signal Name
Pin No.
Signal Name
1
GND
20
HWT#
2
NC
21
HRD#
3
XTLI
22
HD4
4
XTLO
23
HD5
5
RESET#
24
RESERVED
6
HA0
25
DIB_DATAP
7
HA1
26
DIB_DATAN
8
HA2
27
HD6
9
VDD
28
HD7
10
VDD
29
NVMDATA
11
PCLKSEL#
30
VDD
12
HD0
31
LPO
13
NVMCLK/PARIF
32
VDD_CORE
14
GND
33
GND
15
HD1
34
PWRCLKP
16
HD2
35
PWRCLKN
17
HD3
36
DSPKOUT
18
HCS#
37
NC
19
HINT
38
GND
CX86500 SCXV.xx Modem Data Sheet
3-14 Conexant 102287H
Table 3-6. CX86500 Modem 38-Pin TSSOP with Parallel Interface Hardware Signal Definitions
Label
Pin
I/O
I/O Type
Signal Name/Description
System
XTLI
3
I
Ix
Crystal Oscillator Input. Connect XTLI to a 28.224 MHz or 27.000 MHz
crystal or clock oscillator circuit. (See PCLKSEL# pin description.)
XTLO
4
O
Ox
Crystal Oscillator Output If XTLI is connected to a 28.224 MHz or
27.000 MHz crystal circuit, also connect XTLO to the crystal circuit; if
XTLI is connected to a 28.224 MHz or 27.000 MHz clock oscillator
circuit, leave XTLO open.
PCLKSEL#
11
I
Ipu/O2
Clock Frequency Select. Clock frequency is selected by PCLKSEL#
during reset processing. Leave open for 27.000 MHz operation; connect
pin to digital ground (GND) for 28.224 MHz operation.
RESET#
5
I
Ipu/O2
Reset. The active low RESET# input resets the modem logic and clears
the internal SRAM.
RESET# low holds the modem in the reset state; RESET# going high
releases the modem from the reset state. After application of VDD,
RESET# must be held low for at least 15 ms after the VDD power
reaches operating range. The modem device set is ready to use 25 ms
after the low-to-high transition of RESET#.
VDD_CORE
32
O
PWR
Core Supply Voltage. Internal +1.8 V core voltage for decoupling. Do
not connect this pin to an external +1.8 V power supply.
VDD
9, 10, 30
I
PWR
Digital Supply Voltage. Connect to +3.3V.
GND
1, 14, 33,
38
I
GND
Digital Ground. Connect to digital ground (GND).
LPO
31
I
Rx
Low Power Oscillator. Connect to +3.3V through 240 K.
Speaker Interface
DSPKOUT
36
O
Ipd/O2
Modem Speaker Digital Output. The DSPKOUT digital output reflects
the received analog input signal digitized to TTL high or low level by an
internal comparator.
DIB Interface
PWRCLKP
34
O
Odpc
Clock and Power Positive. Provides clock and power to the LSD.
Connect to DIB transformer primary winding non-dotted terminal.
PWRCLKN
35
O
Odpc
Clock and Power Negative. Provides clock and power to the LSD.
Connect to DIB transformer primary winding dotted terminal.
DIB_DATAP
25
I/O
Idd/Odd
Data Positive. Transfers data, control, and status information between
the CX86500 and the LSD. Connect to LSD through DIB data positive
channel components.
DIB_DATAN
26
I/O
Idd/Odd
Data Negative. Transfers data, control, and status information between
the CX86500 and the LSD. Connect to LSD through DIB data negative
channel components.
NVRAM Interface
NVMCLK/PARIF
13
I/O
Ipu/O2
NVRAM Clock. During normal operation, NVMCLK/PARIF output high
enables the EEPROM. Connect to EEPROM SCL pin.
Parallel/Serial Interface Select. During reset processing: parallel host
interface is selected by NVMCLK/PARIF high (by internal pullup when no
external pullup is connected to the pin); serial host interface is selected
by NVMCLK/PARIF low (pin connected to GND through a 10 K
pulldown resistor).
NVMDATA
29
I/O
Ipu/O2
NVRAM Data. The NVMDATA pin supplies a serial data interface to the
EEPROM. Connect to EEPROM SDA pin and to +3.3V through 10 K.
CX86500 SCXV.xx Modem Data Sheet
102287H Conexant 3-15
Table 3-6. CX86500 Modem 38-Pin TSSOP with Parallel Interface Hardware Signal Definitions (Continued)
Label
Pin
I/O
I/O Type
Signal Name/Description
Parallel Host Interface
HCS#
18
I
Ipu/O2
Host Bus Chip Select. HCS# input low enables the MCU host bus
interface.
HWT#
20
I
Ipu/O2
Host Bus Write. HWT# is an active low, write control input. When HCS#
is low, HWT# low allows the host to write data or control words into a
selected MCU register.
HRD#
21
I
Ipu/O2
Host Bus Read. HRD# is an active low, read control input. When HCS#
is low, HRD# low allows the host to read status information or data from
a selected MCU register.
HINT
19
O
Ipd/O2
Host Bus Interrupt. HINT output is set high when the receiver error flag,
received data available, transmitter holding register empty, or modem
status interrupt is asserted. HINT is reset low upon the appropriate
interrupt service or master reset operation.
HA0-HA2
6-8
I
Ipu/O2
Host Bus Address Lines 0-2. During a host read or write operation with
HCS# low, HA0-HA2 select an internal MCU 16550A-compatible
register.
HD0-HD7
12, 15-17,
22, 23, 27,
28
I/O
Ippu/O2
Host Bus Data Lines 0-7. HD0-HD7 are three-state input/output lines
providing bidirectional communication between the host and the MCU.
Data, control words, and status information are transferred over HD0-
HD7.
Reserved
RESERVED
24
Reserved. Connect to digital ground (GND).
No Connect
NC
2, 37
No Internal Connection. Leave open.
Note:
I/O Types: See Table 3-7.
CX86500 SCXV.xx Modem Data Sheet
3-16 Conexant 102287H
3.3 CX86500 Electrical Characteristics
CX86500 I/O types are defined in Table 3-7.
CX86500 DC electrical characteristics are listed in Table 3-8.
Table 3-7. CX86500 Modem I/O Type Definitions
I/O Type
Description
Idd/Odd
Digital input/output, DIB data transceiver
Ix/Ox
I/O, wire
Ipd/O2
Digital input, 310 k pull-down / Digital output, 2 mA
Ipu/O2
Digital input, 30 k pull-up / Digital output, 2 mA
Ippu/O2
Digital input, Programmable 30 k pull-up / Digital output, 2 mA
Odpc
Digital output with adjustable drive, DIB clock and power
Rx
Oscillator Pad, place 240 k resistor from pad to VDD
PWR
VCC Power
GND
Ground
NOTES:
1. See DC characteristics in Table 3-8.
2. I/O Type corresponds to the device Pad Type. The I/O column in signal interface tables refers to signal I/O direction used in
the application.
Table 3-8. CX86500 Modem DC Electrical Characteristics
Parameter
Symbol
Min.
Max.
Units
Test Conditions
Input Voltage Low
VIL
0
0.3 *VDD
V
Input Voltage High
VIH
0.7 * VDD
VDD
V
Input Current (no Pull-Down
or Pull-Up)
IIL
-1
+1
uA
OEN = 1
Input Current (Pull-Down)
IPD
+6
+30
uA
VIN = VDD
Input Current (Pull-Up)
IPU
-300
-60
uA
VIN = GND
Output Voltage Low
VOL
0
0.4
V
IOL = +2 mA
Output Voltage High
VOH
VDD-0.4
VDD
V
IOL = -2 mA
Output Impedance
Z
25
95
Pull-Up Resistance
Rpu
12
50
k
VIN = GND
Pull-Down Resistance
Rpd
120
500
k
VIN = VDD
Test Conditions unless otherwise stated: VDD = +3.3 ± 0.3 VDC; TA = 0°C to 70°C; external load = 50 pF.
CX86500 SCXV.xx Modem Data Sheet
102287H Conexant 3-17
3.4 CX20493 LSD 28-Pin QFN Hardware Pins and Signals
3.4.1 CX20493 LSD 28-Pin QFN Signal Summary
3.4.1.1 CX86500 Interface (Through DIB)
The DIB interface, power, and ground signals are:
Clock (CLK, pin 26); input
Digital Power (PWR+, pin 7); unregulated input power
Regulated Digital Voltage Supply (DVdd, pin 24)
Digital Ground (DGnd, pin 23); digital ground
Regulated Analog Voltage Supply (AVdd, pin 2)
Analog Ground (AGnd, pin 6); analog ground
Data Positive (DIB_P, pin 27); input/output
Data Negative (DIB_N, pin 28); input/output
3.4.1.2 Telephone Line Interface
The telephone line interface signals are:
RING 1 AC Coupled (RAC1, pin 21); input
TIP 1 AC Coupled (TAC1, pin 20); input
RING 2 AC Coupled (RAC2, pin 19); input
TIP 2 AC Coupled (TAC2, pin 18); input
TIP and RING DC Measurement (TRDC, pin 12); input
Electronic Inductor Capacitor (EIC, pin 11)
Electronic Inductor Output (EIO, pin 17)
Electronic Inductor Feedback (EIF, pin 16)
Receive Analog Input (RXI, pin 9); input
Transmit Output (TXO, pin 14); output
Transmit Feedback (TXF, pin 13); input
Virtual Impedance 0 (VZ, pin 10); input
Electronic Inductor Ground (DC_GND, pin 15)
3.4.1.3 Voltage References
There are three reference voltage pins:
Output Middle (Center) Reference Voltage (Vc, pin 3); output for decoupling
Output Reference Voltage (VRef, pin 4); output for decoupling
Bias Resistor (RBias, pin 5); input
CX86500 SCXV.xx Modem Data Sheet
3-18 Conexant 102287H
3.4.1.4 General Purpose Input/Output
There is one unassigned general purpose input/output pin:
General Purpose Input/Output 1 (GPIO1, pin 1); input/output
3.4.1.5 No Connects
Three pins are not used:
No Connect 1 (NC1, pin 8); no internal connection
No Connect 2 (NC2, pin 22); no internal connection
No Connect 3 (NC3, pin 25); no internal connection
3.4.2 CX20493 LSD Pin Assignments and Signal Definitions
CX20493 LSD hardware interface signals are shown by major interface in Figure 3-7, are
shown by pin number in Figure 3-8, and are listed by pin number in Table 3-9.
CX20493 LSD hardware interface signals are defined in Table 3-10.
Figure 3-7. CX20493 LSD 28-Pin QFN Hardware Interface Signals
RAC2
TAC2
RAC1
TAC1
EIC
TRDC
EIO
EIF
RXI
VZ
TXO
TXF
RBias
VRef
Vc
GPIO1
NC1
NC2
NC3
19
18
21
20
11
12
17
16
9
10
14
13
5
4
3
1
8
22
25
101701_006
CX20493
SmartDAA 3
Line Side
Device
(LSD)
28-Pin QFN
Electronic
Inductor,
Off-Hook,
Pulse Dial,
and TIP and
RING VI
Control
AGND_LSD
Safety
and EMI
Protection
Ring
Filter
AGND_LSD
C944
Receive
Coupling
Impedance
Matching
and
Transmitter
NC
NC
NC
NC
R954
AGND_LSD
DVdd
CLK
PWR+
AVdd
AGnd
DIB_P
DIB_N
PADDLE
DC_GND
DGND
24
26
7
2
6
27
28
29
15
23
C930 C928
AGND_LSD
DIGITAL
ISOLATION
BARRIER
(DIB)
PWRCLKN
PWRCLKP
DIB_DATAP
DIB_DATAN
DATA
CHANNEL
POWER AND
CLOCK
CHANNEL
R922
C922
C924
Telephone
Line
Connector TIP
RING
C926
R932
Vdd
C952
C950
NOTE:
Consult applicable reference design for exact
component placement and values, and for layout guidelines.
C962
C974 C976
R990
C970
C978
DGND_LSD
Vdd
AGND_LSD DGND_LSD
GND_TIE
U908
C940
FB906
On-hook
Monitor
(Optional)
R950
R952
AGND_LSD
BR908
BR908 CC
BR908 AC1
PCLK2 CLK2
+ -
R924
R926
CX86500 SCXV.xx Modem Data Sheet
102287H Conexant 3-19
Figure 3-8. CX20493 LSD 28-Pin QFN Pin Signals
101701A_007
1
2
3
4
5
6
7
8
9
10
11
12
13
14
28
27
26
25
24
23
22
21
20
19
18
17
16
15
GPIO1
AVdd
Vc
Vref
RBias
AGnd
PWR+
RAC1
TAC1
RAC2
TAC2
EIO
EIF
DC_GND
NC1
RXI
VZ
EIC
TRDC
TXF
TXO
DIB_N
DIB_P
CLK
NC3
DVdd
DGnd
NC2
CX20493
Table 3-9. CX20493 LSD 28-Pin QFN Pin Signals
Pin
Signal Label
Pin
Signal Label
1
GPIO1
15
DC_GND
2
AVdd
16
EIF
3
Vc
17
EIO
4
VRef
18
TAC2
5
RBias
19
RAC2
6
AGnd
20
TAC1
7
PWR+
21
RAC1
8
NC1
22
NC2
9
RXI
23
DGnd
10
VZ
24
DVdd
11
EIC
25
NC3
12
TRDC
26
CLK
13
TXF
27
DIB_P
14
TXO
28
DIB_N
CX86500 SCXV.xx Modem Data Sheet
3-20 Conexant 102287H
Table 3-10. CX20493 LSD 28-Pin QFN Hardware Signal Definitions
Label
Pin
I/O
I/O Type
Signal Name/Description
System Signals
AVdd
2
PWR
PWR
Regulated Power Output. Provides external power for LSD digital
circuits and a connection point for external decoupling. (AVdd is routed
internally to LSD analog circuits.) See PWR+ pin description. Connect to
LSD DVdd pin and connect to AGND_LSD through C928 and C930 in
parallel. C928 and C930 must be placed close to pins 2 and 6. C930
must have ESR < 2 .
AGnd
6
AGND_LSD
AGND_LSD
Analog Ground. Connect to minus (-) terminal of full wave rectifier
(FWR). Connect FWR BR980 terminal to DIB transformer secondary
winding undotted terminal through R922.
VRef
4
REF
REF
Output Reference Voltage. Connect to AGND_LSD through C940 and
C976, which must be placed close to pin 4. Ensure a very close proximity
between C940 and the VRef pin. C940 must have a maximum ESR of
2 .
Vc
3
REF
REF
Output Middle Reference Voltage. Connect to AGND_LSD through
C944 and C974, which must be placed close to pin 3. Ensure a very
close proximity between C944 and the Vc pin. Use a short path and a
wide trace to AGND_LSD pin.
PWR+
7
PWR
PWR
Unregulated Power Input. Provides unregulated input power to the
LSD. PWR+ pin is an input which takes unregulated +3.2V to +4.5V from
the DIB power supply made up of the transformer, full-wave rectifier, and
filter capacitors. The PWR+ input is regulated by an internal linear
regulator to +3.3V 5% which is routed to the AVdd pin. If PWR+ is less
than +3.4V, then AVdd is equal to the unregulated PWR+ input value
minus 150 mV (Table 3-14).
Connect to plus (+) terminal of FWR. Connect terminal BR908 AC1 to
DIB transformer secondary winding dotted terminal through R990.
Connect transformer side of FB906 to AGND_LSD though C970. Place
FB906 and C970 close to pin 7 and pin 6 (AGnd).
DVdd
24
PWR
PWR
Digital Power Input. Input power for LSD digital circuits. Connect to LSD
AVdd pin and connect to DGND_LSD through C978. Place C978 near
pin 24.
DGnd
23
DGND_LSD
DGND_LSD
LSD Digital Ground. Connect to DGND_LSD, and to AGND_LSD at the
DGND_LSD/AGND_LSD tie point (U908).
PADDLE
—
AGND_LSD
AGND_LSD
Paddle Ground. Referred to as pin 29 in schematics. Connect to
AGND_LSD.
DIB Interface Signals
CLK
26
I
I
Clock. Provides input clock, AC coupled to the LSD. Connect to DIB
transformer secondary winding undotted terminal through C926 (closest
to the CX20493), R932, then R922 in series. Connect the R932 and
R922 node to LSD AGND pin through full-wave rectifier BR908. Place
C926 near pin 26 and place R932 near C926.
DIB_P
27
I/O
I/O
Data and Control Positive. Connect to DIBDAT_P through R924 in
series with C922. DIB_P and DIB_N signals are differential and half-
duplex bidirectional.
DIB_N
28
I/O
I/O
Data and Control Negative. Connect to DIBDAT_N through R926 in
series with C924. DIB_P and DIB_N signals are differential and half-
duplex bidirectional.
CX86500 SCXV.xx Modem Data Sheet
102287H Conexant 3-21
Table 3-10. CX20493 LSD 28-Pin QFN Hardware Signal Definitions (Continued)
Label
Pin
I/O
I/O Type
Signal Name/Description
TIP and RING Interface
RAC1
TAC1
21
20
I
I
Ia
Ia
RING1 AC Coupled and TIP1 AC Coupled. AC-coupled voltage from
telephone line used to detect ring.
Connect RAC1 to the diode bridge AC node (RING) through R902
(connects to pin 21) and C902 in series.
Connect TAC1 to the diode bridge AC node (TIP) through R904
(connects to pin 20) and C904 in series.
RAC2
TAC2
19
18
I
I
Ia
Ia
RING2 AC Coupled and TIP2 AC Coupled. AC-coupled voltage from
telephone line used to optionally detect signal while on-hook.
Connect RAC2 to the diode bridge AC node (RING) through R948
(connects to pin 19) and C948. Leave open if not used.
Connect TAC2 to the diode bridge AC node (TIP) through R946
(connects to pin 21) and C946. Leave open if not used.
EIC
11
O
Oa
Electronic Inductor Capacitor Switch. Internally switched to TRDC
when pulse dialing. Connect to AGND_LSD through C958.
TRDC
12
I
Ia
TIP and RING DC Measurement. Input on-hook voltage (from a resistive
divider). Used internally to extract TIP and RING DC voltage and Line
Polarity Reversal (LPR) information. R906 and C918 must be placed
very close to pin 12.
EIO
17
O
Oa
Electronic Inductor Output. Calculated voltage is applied to this output
to control off-hook and DC VI mask operation. Connect to base of Q902.
DC_GND
15
GND
AGND_LSD
LSD Electronic Inductor Ground. Connect to AGND_LSD and to the
GND_LSD/AGND_LSD tie point (U908).
EIF
16
I
Ia
Electronic Inductor Feedback. Connect to emitter of Q904 through
R968.
RXI
9
I
Ia
Receive Analog Input. Receiver operational amplifier inverting input.
AC coupled to the Bridge CC node through R910 (connects to pin 9) and
C912 in series. R910 and C912 must be placed very close to pin 9. The
length of the PCB trace connecting R910 to the RXI pin must be kept at
an absolute minimum.
RBias
5
I
Ia
Receiver Bias. Connect to AGND_LSD through R954, which must be
placed close to pin 5.
VZ
10
I
Ia
Virtual Impedance. Input signal used to provide line complex
impedance matching for worldwide countries. AC coupled to Bridge CC
node through R908 (connects to pin 10) and C910 in series. R908 and
C910 must be placed very close to pin 10. The length of the PCB trace
connecting R908 to the VZ pin must be kept at an absolute minimum.
TXO
14
O
Oa
Transmit Output. Outputs transmit signal and impedance matching
signal; connect to base of transmitter transistor Q906.
TXF
13
I
Ia
Transmit Feedback. Connect to emitter of transmitter transistor Q906.
Not Used
GPIO1
1
I/O
It/Ot12
General Purpose I/O 1. Leave open if not used.
NC1
8
No Connect. No internal connection. Leave open.
NC2
22
No Connect. No internal connection. Leave open.
NC3
25
No Connect. No internal connection. Leave open.
Notes:
1. I/O types*:
Ia Analog input
It Digital input, TTL-compatible
Oa Analog output
Ot12 Digital output, TTL-compatible, 12 mA, ZINTERNAL = 32
AGND_LSD Isolated LSD Analog Ground
GND_LSD Isolated LSD Digital Ground
*See CX20493 LSD GPIO DC Electrical Characteristics (Table 3-13).
2. Refer to applicable reference design for exact component placement and values.
CX86500 SCXV.xx Modem Data Sheet
3-22 Conexant 102287H
3.5 CX20493 LSD 32-Pin LQFP Hardware Pins and Signals
3.5.1 CX20493 LSD 32-Pin LQFP Signal Summary
3.5.1.1 CX86500 Interface (Through DIB)
The DIB interface, power, and ground signals are:
Clock (CLK, pin 29); input
Digital Power (PWR+, pin 8); unregulated input power
Regulated Digital Voltage Supply (DVdd, pin 28)
Digital Ground (DGnd, pin 26 and pin 27); digital ground
Regulated Analog Voltage Supply (AVdd, pin 2 and pin 3)
Analog Ground (AGnd, pin 7); analog ground
Data Positive (DIB_P, pin 30); input/output
Data Negative (DIB_N, pin 31); input/output
3.5.1.2 Telephone Line Interface
The telephone line interface signals are:
RING 1 AC Coupled (RAC1, pin 24); input
TIP 1 AC Coupled (TAC1, pin 23); input
RING 2 AC Coupled (RAC2, pin 22); input
TIP 2 AC Coupled (TAC2, pin 21); input
TIP and RING DC Measurement (TRDC, pin 13); input
Electronic Inductor Capacitor (EIC, pin 12)
Electronic Inductor Output (EIO, pin 20)
Electronic Inductor Feedback (EIF, pin 19)
Receive Analog Input (RXI, pin 10); input
Transmit Output (TXO, pin 15); output
Transmit Feedback (TXF, pin 14); input
Virtual Impedance 0 (VZ, pin 11); input
Electronic Inductor Ground (DC_GND, pins 1, 9, 16, 18, and 25)
3.5.1.3 Voltage References
There are three reference voltage pins:
Output Middle (Center) Reference Voltage (Vc, pin 4); output for decoupling
Output Reference Voltage (VRef, pin 5); output for decoupling
Bias Resistor (RBias, pin 6); input
CX86500 SCXV.xx Modem Data Sheet
102287H Conexant 3-23
3.5.1.4 General Purpose Input/Output
There is one unassigned general purpose input/output pin:
General Purpose Input/Output 1 (GPIO1, pin 32); input/output
3.5.1.5 No Connects
There is one No Connect pin:
No Connect (NC, pin 17); no internal connection
3.5.2 CX20493 LSD 32-Pin LQFP Pin Assignments and Signal Definitions
CX20493 LSD hardware interface signals are shown by major interface in Figure 3-7, are
shown by pin number in Figure 3-8, and are listed by pin number in Table 3-11.
CX20493 LSD hardware interface signals are defined in Table 3-12.
Figure 3-9. CX20493 LSD 32-Pin LQFP Hardware Interface Signals
RAC2
TAC2
RAC1
TAC1
EIC
TRDC
EIO
EIF
RXI
VZ
TXO
TXF
RBias
VRef
Vc
GPIO1
NC
22
21
24
23
12
13
20
19
10
11
15
14
6
5
4
32
17
102247_007
CX20493
SmartDAA 3
Line Side
Device
(LSD)
32-Pin LQFP
Electronic
Inductor,
Off-Hook,
Pulse Dial,
and TIP and
RING VI
Control
AGND_LSD
Safety
and EMI
Protection
Ring
Filter
AGND_LSD
C944
Receive
Coupling
Impedance
Matching
and
Transmitter
NC
NC
R954
AGND_LSD
DVdd
CLK
PWR+
AVdd
AGnd
DIB_P
DIB_N
DC_GND
DGnd
28
29
8
2, 3
7
30
31
1, 9, 16, 18, 25
26, 27
C930 C928
AGND_LSD
DIGITAL
ISOLATION
BARRIER
(DIB)
PWRCLKN
PWRCLKP
DIB_DATAP
DIB_DATAN
DATA
CHANNEL
POWER AND
CLOCK
CHANNEL
R922
C922
C924
Telephone
Line
Connector TIP
RING
C926
R932
Vdd
C952
C950
NOTE:
Consult applicable reference design for exact component
placement and values, and for layout guidelines.
C962
C974 C976
R990
C970
C978
DGND_LSD
Vdd
AGND_LSD DGND_LSD
GND_TIE
U908
C940
FB906
On-hook
Monitor
(Optional)
R950
R952
BR908
BR908 CC
BR908 AC1
PCLK2 CLK2
+ -
R924
R926
CX86500 SCXV.xx Modem Data Sheet
3-24 Conexant 102287H
Figure 3-10. CX20493 LSD 32-Pin LQFP Pin Signals
102247_008
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
32
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
DC_GND
AVdd
AVdd
Vc
VRef
RBias
AGnd
PWR+
RAC1
TAC1
RAC2
TAC2
EIO
EIF
DC_GND
NC
DC_GND
RXI
VZ
EIC
TRDC
TXF
TXO
DC_GND
GPIO1
DIB_N
DIB_P
CLK
DVdd
DGnd
DGnd
DC_GND
CX20493
Table 3-11. CX20493 LSD 32-Pin LQFP Pin Signals
Pin
Signal Label
Pin
Signal Label
1
DC_GND
17
NC
2
AVdd
18
DC_GND
3
AVdd
19
EIF
4
Vc
20
EIO
5
VRef
21
TAC2
6
RBias
22
RAC2
7
AGnd
23
TAC1
8
PWR+
24
RAC1
9
DC_GND
25
DC_GND
10
RXI
26
DGnd
11
VZ
27
DGnd
12
EIC
28
DVdd
13
TRDC
29
CLK
14
TXF
30
DIB_P
15
TXO
31
DIB_N
16
DC_GND
32
GPIO1
CX86500 SCXV.xx Modem Data Sheet
102287H Conexant 3-25
Table 3-12. CX20493 LSD 32-Pin LQFP Pin Signal Definitions
Label
Pin
I/O
I/O Type
Signal Name/Description
System Signals
AVdd
2, 3
PWR
PWR
Regulated Power Output. Provides external power for LSD digital
circuits and a connection point for external decoupling. (AVdd is routed
internally to LSD analog circuits.) See PWR+ pin description. Connect to
LSD DVdd pin and connect to AGND_LSD through C928 and C930 in
parallel. C928 and C930 must be placed close to pin 3 (AVdd) and pin 7
(AGnd). C930 must have ESR < 2 .
AGnd
7
AGND_LSD
AGND_LSD
Analog Ground. Connect to minus (-) terminal of full wave rectifier
(FWR). Connect FWR BR980 terminal to DIB transformer secondary
winding undotted terminal through R922.
VRef
5
REF
REF
Output Reference Voltage. Connect to AGND_LSD through C940 and
C976, which must be placed close to pin 5 (VRef). Ensure a very close
proximity between C940 and pin 5. C940 must have a maximum ESR of
2 .
Vc
4
REF
REF
Output Middle Reference Voltage. Connect to AGND_LSD through
C944 and C974, which must be placed close to pin 4 (Vc). Ensure a very
close proximity between C944 and pin 4. Use a short path and a wide
trace to AGND_LSD pin.
PWR+
8
PWR
PWR
Unregulated Power Input. Provides unregulated input power to the
LSD. PWR+ pin is an input which takes unregulated +3.2V to +4.5V from
the DIB power supply made up of the transformer, full-wave rectifier, and
filter capacitors. The PWR+ input is regulated by an internal linear
regulator to +3.3V 5% which is routed to the AVdd pin. If PWR+ is less
than +3.4V, then AVdd is equal to the unregulated PWR+ input value
minus 150 mV (Table 3-14).
Connect to plus (+) terminal of FWR. Connect terminal BR908 AC1 to
DIB transformer secondary winding dotted terminal through R990.
Connect transformer side of FB906 to AGND_LSD though C970. Place
FB906 and C970 close to pin 8 (PWR+) and pin 7 (AGnd).
DVdd
28
PWR
PWR
Digital Power Input. Input power for LSD digital circuits. Connect to LSD
AVdd pin and connect to DGND_LSD through C978. Place C978 near
pin 27 (DVdd).
DGnd
26, 27
DGND_LSD
DGND_LSD
LSD Digital Ground. Connect to DGND_LSD, and to AGND_LSD at the
DGND_LSD/AGND_LSD tie point (U908).
DIB Interface Signals
CLK
29
I
I
Clock. Provides input clock, AC coupled to the LSD. Connect to DIB
transformer secondary winding undotted terminal through C926 (closest
to the CX20493), R932, then R922 in series. Connect the R932 and
R922 node to LSD AGND pin through full-wave rectifier BR908. Place
C926 near pin 29 (CLK) and place R932 near C926.
DIB_P
30
I/O
I/O
Data and Control Positive. Connect to DIBDAT_P through R924 in
series with C922. DIB_P and DIB_N signals are differential and half-
duplex bidirectional.
DIB_N
31
I/O
I/O
Data and Control Negative. Connect to DIBDAT_N through R926 in
series with C924. DIB_P and DIB_N signals are differential and half-
duplex bidirectional.
CX86500 SCXV.xx Modem Data Sheet
3-26 Conexant 102287H
Table 3-12. CX20493 LSD Pin Signal Definitions (Continued)
Label
Pin
I/O
I/O Type
Signal Name/Description
TIP and RING Interface
RAC1
TAC1
24
23
I
I
Ia
Ia
RING1 AC Coupled and TIP1 AC Coupled. AC-coupled voltage from
telephone line used to detect ring.
Connect RAC1 to the diode bridge AC node (RING) through R902
(connects to pin 24) and C902 in series.
Connect TAC1 to the diode bridge AC node (TIP) through R904
(connects to pin 23) and C904 in series.
RAC2
TAC2
22
21
I
I
Ia
Ia
RING2 AC Coupled and TIP2 AC Coupled. AC-coupled voltage from
telephone line used to optionally detect signal while on-hook.
Connect RAC2 to the diode bridge AC node (RING) through R948
(connects to pin 22) and C948. Leave open if not used.
Connect TAC2 to the diode bridge AC node (TIP) through R946
(connects to pin 21) and C946. Leave open if not used.
EIC
12
O
Oa
Electronic Inductor Capacitor Switch. Internally switched to TRDC
when pulse dialing. Connect to AGND_LSD through C958.
TRDC
13
I
Ia
TIP and RING DC Measurement. Input on-hook voltage (from a resistive
divider). Used internally to extract TIP and RING DC voltage and Line
Polarity Reversal (LPR) information. R906 and C918 must be placed
very close to pin 13 (TRDC).
EIO
20
O
Oa
Electronic Inductor Output. Calculated voltage is applied to this output
to control off-hook and DC VI mask operation. Connect to base of Q902.
DC_GND
1, 9,
16, 18,
25
GND
AGND_LSD
LSD Electronic Inductor Ground. Connect to AGND_LSD and to the
GND_LSD/AGND_LSD tie point (U908).
EIF
19
I
Ia
Electronic Inductor Feedback. Connect to emitter of Q904 through
R968.
RXI
10
I
Ia
Receive Analog Input. Receiver operational amplifier inverting input.
AC coupled to the Bridge CC node through R910 (connects to pin 10)
and C912 in series. R910 and C912 must be placed very close to pin 10.
The length of the PCB trace connecting R910 to the RXI pin must be
kept at an absolute minimum.
RBias
6
I
Ia
Receiver Bias. Connect to AGND_LSD through R954, which must be
placed close to pin 6.
VZ
11
I
Ia
Virtual Impedance. Input signal used to provide line complex
impedance matching for worldwide countries. AC coupled to Bridge CC
node through R908 (connects to pin 11) and C910 in series. R908 and
C910 must be placed very close to pin 11. The length of the PCB trace
connecting R908 to the VZ pin must be kept at an absolute minimum.
TXO
15
O
Oa
Transmit Output. Outputs transmit signal and impedance matching
signal; connect to base of transmitter transistor Q906.
TXF
14
I
Ia
Transmit Feedback. Connect to emitter of transmitter transistor Q906.
Not Used
GPIO1
32
I/O
It/Ot12
General Purpose I/O 1. Leave open if not used.
NC
17
No Connect. No internal connection. Leave open.
Notes:
1. I/O types*:
Ia Analog input
It Digital input, TTL-compatible
Oa Analog output
Ot12 Digital output, TTL-compatible, 12 mA, ZINTERNAL = 32
AGND_LSD Isolated LSD Analog Ground
GND_LSD Isolated LSD Digital Ground
*See CX20493 LSD GPIO DC Electrical Characteristics (Table 3-13).
2. Refer to applicable reference design for exact component placement and values.
CX86500 SCXV.xx Modem Data Sheet
102287H Conexant 3-27
3.6 CX20493 LSD GPIO DC Electrical Characteristics
CX20493 LSD GPIO DC electrical characteristics are specified in Table 3-13.
CX20493 LSD AVdd DC electrical characteristics are listed in Table 3-14.
Table 3-13. CX20493 LSD GPIO DC Electrical Characteristics
Parameter
Symbol
Min.
Typ.
Max.
Units
Test Conditions
Input Voltage
VIN
-0.30
–
3.465
V
DVdd = +3.465V
Input Voltage Low
VIL
–
–
1.0
V
Input Voltage High
VIH
1.6
–
–
V
Output Voltage Low
VOL
0
–
0.33
V
Output Voltage High
VOH
2.97
–
–
V
Input Leakage Current
–
-10
–
10
µA
Output Leakage Current (High Impedance)
–
-10
–
10
µA
GPIO Output Sink Current at 0.33 V maximum
–
2.4
–
-
mA
GPIO Output Source Current at 2.97 V minimum
–
2.4
–
-
mA
GPIO Rise Time/Fall Time
20
100
ns
Test Conditions unless otherwise stated: DVdd = +3.3V +5%; TA = 0°C to 70°C; external load = 50 pF
Table 3-14. CX20493 AVdd DC Electrical Characteristics
PWR+ Input
AVdd Output
+3.4V < PWR+ < +4.5V
+3.3V 5%
+3.2V < PWR+ < +3.39V
3.05V < AVdd < 3.24V
See PWR+, AVdd, and DVdd descriptions in Table 3-10.
CX86500 SCXV.xx Modem Data Sheet
3-28 Conexant 102287H
3.7 Electrical and Environmental Specifications
3.7.1 Operating Conditions, Absolute Maximum Ratings, and Power
Requirements
The operating conditions are specified in Table 3-15.
The absolute maximum ratings are listed in Table 3-16.
The current and power requirements are listed in Table 3-17.
Table 3-15. Operating Conditions
Parameter
Symbol
Limits
Units
Supply Voltage
VDD
+3.0 to +3.6
VDC
Operating Ambient Temperature
TA
0 to +70
°C
Table 3-16. Absolute Maximum Ratings
Parameter
Symbol
Limits
Units
Supply Voltage
VDD
-0.5 to +4.0
VDC
Input Voltage
VIN
-0.5 to VDD + 0.5
VDC
Storage Temperature Range
TSTG
-55 to +125
°C
Voltage Applied to Outputs in High
Impedance (Off) State
VHZ
-0.5 to +5.5
VDC
DC Input Clamp Current
IIK
±20
mA
DC Output Clamp Current
IOK
±20
mA
Static Discharge Voltage (25°C)
VESD
±2500
VDC
Latch-up Current (25°C)
ITRIG
±400
mA
Handling CMOS Devices
The device contains circuitry to protect the inputs against damage due to high static
voltages. However, it is advised that normal precautions be taken to avoid application of
any voltage higher than maximum rated voltage.
An unterminated input can acquire unpredictable voltages through coupling with stray
capacitance and internal cross talk. Both power dissipation and device noise immunity
degrades. Therefore, all inputs should be connected to an appropriate supply voltage.
Input signals should never exceed the voltage range from -0.5V to (VDD + 0.5) V. This
prevents forward biasing the input protection diodes and possibly entering a latch up
mode due to high current transients.
CX86500 SCXV.xx Modem Data Sheet
102287H Conexant 3-29
Table 3-17. Current and Power Requirements
Mode
Typical
Current
(Ityp)
(mA)
Maximum
Current
(Imax)
(mA)
Typical
Power
(Ptyp)
(mW)
Maximum
Power
(Pmax)
(mW)
Normal Mode: On-hook, idle, waiting for ring
125
140
413
504
Normal Mode: Off-hook, normal data connection
130
145
429
522
Idle Mode
28
33
92
119
Sleep Mode
18
23
60
83
Stop Mode
10
13
33
47
Notes:
1. Operating voltage: VDD = +3.3V ± 0.3V.
2. Test conditions: VDD = +3.3V for typical values; VDD = +3.6V for maximum values.
3. Input Ripple 0.1 Vpeak-peak.
4. Typical power (Ptyp) computed from Ityp: Ptyp = Ityp * 3.3V;
Maximum power (Pmax) computed from Imax: Pmax = Imax * 3.6V.
CX86500 SCXV.xx Modem Data Sheet
3-30 Conexant 102287H
3.7.2 Interface and Timing Waveforms
3.7.2.1 Serial DTE Interface
The serial DTE interface waveforms for 4800 and 9600 bps are illustrated in Figure 3-11.
Figure 3-11. Waveforms - Serial DTE Interface
CX86500 SCXV.xx Modem Data Sheet
102287H Conexant 3-31
3.7.2.2 Parallel Host Bus Interface
The parallel host bus timing is listed in Table 3-18 and illustrated in Figure 3-12.
Table 3-18. Timing - Parallel Host Bus
Symbol
Parameter
Max
Units
WRITE
tAS
Address Setup
–
ns
tAH
Address Hold
–
ns
tCS
Chip Select Setup
–
ns
tCH
Chip Select Hold
–
ns
tWWH
Write Pulse Width High
ns
tWWL
Write Pulse Width Low
ns
tDS
Write Data Setup
–
ns
tDWH
Write Data Hold
–
ns
READ
tAS
Address Setup
–
ns
tAH
Address Hold
–
ns
tCS
Chip Select Setup
–
ns
tCH
Chip Select Hold
–
ns
tRRH
Read Pulse Width High
ns
tRRL
Read Pulse Width Low
ns
tDD
Read Data Delay
9
ns
tDRH
Read Data Hold
–
ns
CX86500 SCXV.xx Modem Data Sheet
3-32 Conexant 102287H
Figure 3-12. Waveforms - Parallel Host Bus
HA[2:0]
HCS#
HWT#
HD[7:0] Valid
Valid
tWWL
a. Host Bus Write
tAS tAH
tCS tCH
tDWH
tDS
HA[2:0]
HCS#
HRD#
HD[7:0] Valid
Valid
tRRL
b. Host Bus Read
tAS tAH
tCS tCH
tDD tDRH
tRRH
tWWH
102287_009
CX86500 SCXV.xx Modem Data Sheet
102287H Conexant 3-33
3.7.2.3 Voice Pass-Through Interface – 14-Bit PCM
The Voice Pass-Through 14-bit PCM receive and transmit serial interface waveforms are
illustrated in Figure 3-13.
Figure 3-13. Waveforms – 14-Bit PCM Receive and Transmit Timing
D7
B1 D8
B2 D9
B3
D10
B4 D11
B5 D12
B6
D13
B7 D0
B1 D1
B2 D2
B3 D3
B4 D4
B5 D5
B6
D6
B7 Stop
Stop
Start B0
RXD/TXD Start
102287_010
Most Significant Byte Least Significant Byte
3.8 Crystal and Clock Specifications
Crystal specifications are listed in Table 3-19. Clock specifications are listed in
Table 3-20.
Table 3-19. Crystal Specifications
Characteristic
Value
Frequency
28.224 or 27.000 MHz nominal
Calibration Tolerance
±50 ppm at 25°C (CL = 16.5 and 19.5 pF)
Frequency Stability vs. Temperature
±35 ppm (0°C to 70°C)
Frequency Stability vs. Aging
±20 ppm/5 years
Oscillation Mode
Fundamental
Calibration Mode
Parallel resonant
Load Capacitance, CL
18 pF nom.
Shunt Capacitance, CO
7 pF max.
Series Resistance, R1
35-60 max. @20 nW drive level
Drive Level
100 µW correlation; 500 µW max.
Operating Temperature
0°C to 70°C
Storage Temperature
–40°C to 85°C
Table 3-20. Clock Specifications
Characteristic
Value
Type
Square wave
Frequency
28.224 or 27.000 MHz nominal
Level
3.3 Vp-p ± 0.3 V zero offset
Duty Cycle
50 ± 10 %
Stability
±50 ppm
CX86500 SCXV.xx Modem Data Sheet
3-34 Conexant 102287H
This page is intentionally blank.
CX86500 SCXV.xx Modem Data Sheet
102287H Conexant 4-1
4. Parallel Host Interface
The modem supports a 16550A interface in parallel interface versions. The 16550A
interface can operate in FIFO mode or non-FIFO mode. Non-FIFO mode is the same as
16450 interface operation. FIFO mode unique operations are identified.
4.1 Overview
The parallel interface registers and the corresponding bit assignments are shown in
Table 4-1.
The modem emulates the 16450/16550A interface and includes both a 16-byte receiver
data first-in first-out buffer (RX FIFO) and a 16-byte transmit data first-in first-out buffer
(TX FIFO). When FIFO mode is selected in the FIFO Control Register (FCR0 = 1), both
FIFOs are operative. Furthermore, when FIFO mode is selected, DMA operation of the
FIFO can also be selected (FCR3 = 1). When FIFO mode is not selected, operation is
restricted to 16450 interface operation.
The received data is read by the host from the Receiver Buffer (RX Buffer). The RX
Buffer corresponds to the Receiver Buffer Register in a 16550A device. In FIFO mode,
the RX FIFO operates transparently behind the RX Buffer. Interface operation is
described with reference to the RX Buffer in both FIFO and non-FIFO modes.
The transmit data is loaded by the host into the Transmit Buffer (TX Buffer). The TX
Buffer corresponds to the Transmit Holding Register in a 16550A device. In FIFO mode,
the TX FIFO operates transparently behind the TX Buffer. Interface operation is
described with reference to the TX Buffer in both FIFO and non-FIFO modes.
CX86500 SCXV.xx Modem Data Sheet
4-2 Conexant 102287H
Table 4-1. Parallel Interface Registers
Register
Register
Bit No.
No.
Name
7
6
5
4
3
2
1
0
7
Scratch Register (SCR)
Scratch Register
6
Modem Status Register (MSR)
Data Carrier
Detect
(DCD)
Ring
Indicator (RI)
Data Set
Ready
(DSR)
Clear to
Send
(CTS)
Delta Data
Carrier
Detect
(DDCD)
Trailing
Edge of Ring
Indicator
(TERI)
Delta Data
Set Ready
(DDSR)
Delta Clear
to Send
(DCTS)
5
Line Status Register (LSR)
RX FIFO
Error
Transmitter
Empty
(TEMT)
Transmitter
Buffer
Register
Empty
(THRE)
Break
Interrupt (BI)
Framing
Error
(FE)
Parity
Error
(PE)
Overrun
Error
(OE)
Receiver
Data Ready
(DR)
4
Modem Control Register (MCR)
0
0
0
Local
Loopback
Out 2
Out 1
Request to
Send
(RTS)
Data
Terminal
Ready
(DTR)
3
Line Control Register (LCR)
Divisor Latch
Access Bit
(DLAB)
Set Break
Stick Parity
Even Parity
Select (EPS)
Parity
Enable
(PEN)
Number of
Stop Bits
(STB)
Word Length
Select Bit 1
(WLS1)
Word Length
Select Bit 0
(WLS0)
2
Interrupt Identify Register (IIR)
(Read Only)
FIFOs
Enabled
FIFOs
Enabled
0
0
Pending
Interrupt ID
Bit 2
Pending
Interrupt ID
Bit 1
Pending
Interrupt ID
Bit 0
―0" if
Interrupt
Pending
2
FIFO Control Register (FCR)
(Write Only)
Receiver
Trigger MSB
Receiver
Trigger
LSB
Reserved
Reserved
DMA Mode
Select
TX FIFO
Reset
RX FIFO
Reset
FIFO Enable
1
(DLAB = 0)
Interrupt Enable Register (IER)
0
0
0
0
Enable
Modem
Status
Interrupt
(EDSSI)
Enable
Receiver
Line Status
Interrupt
(ELSI)
Enable
Transmitter
Holding
Register
Empty
Interrupt
(ETBEI)
Enable
Received
Data
Available
Interrupt
(ERBFI)
0
(DLAB = 0)
Transmitter Buffer Register
(THR)
Transmitter FIFO Buffer Register (Write Only)
0
(DLAB = 0)
Receiver Buffer Register (RBR)
Receiver FIFO Buffer Register (Read Only)
1
(DLAB = 1)
Divisor Latch MSB Register
(DLM)
Divisor Latch MSB
0
(DLAB = 1)
Divisor Latch LSB Register
(DLL)
Divisor Latch LSB
CX86500 SCXV.xx Modem Data Sheet
102287H Conexant 4-3
4.2 Register Signal Definitions
4.2.1 IER - Interrupt Enable Register (Addr = 1, DLAB = 0)
The IER enables five types of interrupts that can separately assert the HINT output signal
(Table 4-2). A selected interrupt can be enabled by setting the corresponding enable bit to
a 1, or disabled by setting the corresponding enable bit to a 0. Disabling an interrupt in
the IER prohibits setting the corresponding indication in the IIR and assertion of HINT.
Disabling all interrupts (resetting IER0 - IER3 to a 0) inhibits setting of any Interrupt
Identifier Register (IIR) bits and inhibits assertion of the HINT output. All other system
functions operate normally, including the setting of the Line Status Register (LSR) and
the Modem Status Register (MSR).
Bits 7-4 Not used.
Always 0.
Bit 3 Enable Modem Status Interrupt (EDSSI).
This bit, when a 1, enables assertion of the HINT output whenever the Delta CTS
(MSR0), Delta DSR (MSR1), Delta TER (MSR2), or Delta DCD (MSR3) bit in the
Modem Status Register (MSR) is a 1. This bit, when a 0, disables assertion of HINT
due to setting of any of these four MSR bits.
Bit 2 Enable Receiver Line Status Interrupt (ELSI).
This bit, when a 1, enables assertion of the HINT output whenever the Overrun Error
(LSR1), Parity Error (LSR2), Framing Error (LSR3), or Break Interrupt (LSR4)
receiver status bit in the Line Status Register (LSR) changes state. This bit, when a 0,
disables assertion of HINT due to change of the receiver LSR bits 1-4.
Bit 1 Enable Transmitter Holding Register Empty Interrupt (ETBEI).
This bit, when a 1, enables assertion of the HINT output when the Transmitter Empty
bit in the Line Status Register (LSR5) is a 1. This bit, when a 0, disables assertion of
HINT due to LSR5.
Bit 0 Enable Receiver Data Available Interrupt (ERBFI) and Character
Timeout in FIFO Mode.
This bit, when a 1, enables assertion of the HINT output when the Receiver Data Ready
bit in the Line Status Register (LSR0) is a1 or character timeout occurs in the FIFO
mode. This bit, when a 0, disables assertion of HINT due to the LSR0 or character
timeout.
CX86500 SCXV.xx Modem Data Sheet
4-4 Conexant 102287H
4.2.2 FCR - FIFO Control Register (Addr = 2, Write Only)
The FCR is a write-only register used to enable FIFO mode, clear the RX FIFO and TX
FIFO, enable DMA mode, and set the RX FIFO trigger level.
Bits 7-6 RX FIFO Trigger Level.
FCR7 and FCR6 set the trigger level for the RX FIFO (Receiver Data Available)
interrupt.
FCR7
FCR6
RX FIFO Trigger Level (Bytes)
0
0
01
0
1
04
1
0
08
1
1
14
Bits 5-4 Not used.
Bit 3 DMA Mode Select.
When FIFO mode is selected (FCR0 = 1), FCR3 selects non-DMA operation (FCR3 =
0) or DMA operation (FCR3 = 1). When FIFO mode is not selected (FCR0 = 0), this
bit is not used (the modem operates in non-DMA mode in 16450 operation).
DMA operation in FIFO mode.
RXRDY will be asserted when the number of characters in the RX FIFO is equal to or
greater than the value in the RX FIFO Trigger Level (IIR0-IIR3 = 4h) or the received
character timeout (IIR0-IIR3 = Ch) has occurred. RXRDY will go inactive when there
are no more characters in the RX FIFO.
TXRDY will be asserted when there are one or more empty (unfilled) locations in the
TX FIFO. TXRDY will go inactive when the TX FIFO is completely full.
Non-DMA operation in FIFO mode.
RXRDY will be asserted when there are one or more characters in the RX FIFO.
RXRDY will go inactive when there are no more characters in the RX FIFO.
TXRDY will be asserted when there are no characters in the TX FIFO. TXRDY will go
inactive when the first character is loaded into the TX FIFO Buffer.
Bit 2 TX FIFO Reset.
When FCR2 is a 1, all bytes in the TX FIFO are cleared. This bit is cleared
automatically by the modem.
Bit 1 RX FIFO Reset.
When FCR1 is a 1, all bytes in the RX FIFO are cleared. This bit is cleared
automatically by the modem.
Bit 0 FIFO Enable.
When FCR0 is a 0, 16450 mode is selected and all bits are cleared in both FIFOs.
When FCR0 is a 1, FIFO mode (16550A mode) is selected and both FIFOs are
enabled. FCR0 must be a 1 when other bits in the FCR are written or they will not be
acted upon.
CX86500 SCXV.xx Modem Data Sheet
102287H Conexant 4-5
4.2.3 IIR - Interrupt Identifier Register (Addr = 2)
The Interrupt Identifier Register (IIR) identifies the existence and type of up to five
prioritized pending interrupts. Four priority levels are set to assist interrupt processing in
the host. The four levels, in order of decreasing priority, are: Highest: Receiver Line
Status, 2: Receiver Data Available or Receiver Character Timeout, 3: TX Buffer Empty,
and 4: Modem Status.
When the IIR is accessed, the modem freezes all interrupts and indicates the highest
priority interrupt pending to the host. Any change occurring in interrupt conditions are
not indicated until this access is complete.
Bits 7-6 FIFO Mode.
These two bits copy FCR0.
Bits 5-4 Not Used.
Always 0.
Bits 3-1 Highest Priority Pending Interrupt.
These three bits identify the highest priority pending interrupt (Table 4-2). Bit 3 is
applicable only when FIFO mode is selected, otherwise bit 3 is a 0.
Bit 0 Interrupt Pending.
When this bit is a 0, an interrupt is pending; IIR bits 1-3 can be used to determine the
source of the interrupt. When this bit is a1, an interrupt is not pending.
Table 4-2. Interrupt Sources and Reset Control
Interrupt Identification Register
Interrupt Set and Reset Functions
Bit
31
Bit 2
Bit 1
Bit 0
Priority
Level
Interrupt Type
Interrupt Source
Interrupt Reset Control
0
0
0
1
—
None
None
—
0
1
1
0
Highest
Receiver Line
Status
Overrun Error OE (LSR1),
Parity Error (PE) (LSR2),
Framing Error (FE) (LSR3),
or Break Interrupt (BI) (LSR4)
Reading the LSR
0
1
0
0
2
Received Data
Available
Received Data Available (LSR0) or
RX FIFO Trigger Level (FCR6-
FCR7) Reached1
Reading the RX Buffer or the RX
FIFO drops below the Trigger
Level
1
1
0
0
3
Character Time-out
Indication 1
The RX FIFO contains at least 1
character and no characters have
been removed from or input to the
RX FIFO during the last 4 character
times.
Reading the RX Buffer
0
0
1
0
4
TX Buffer Empty
TX Buffer Empty
Reading the IIR or writing to the
TX Buffer
0
0
0
0
5
Modem Status
Delta CTS (DCTS) (MSR0),
Delta DSR (DDSR) (MSR1),
Trailing Edge Ring Indicator (TERI)
(MSR3), or Delta DCD (DCD)
(MSR4)
Reading the MSR
Notes:
1. FIFO Mode only.
CX86500 SCXV.xx Modem Data Sheet
4-6 Conexant 102287H
4.2.4 LCR - Line Control Register (Addr = 3)
The Line Control Register (LCR) specifies the format of the asynchronous data
communications exchange.
Bit 7 Divisor Latch Access Bit (DLAB).
This bit must be set to a 1 to access the Divisor latch registers during a read or write
operation. It must be reset to a 0 to access the Receiver Buffer, the Transmitter Buffer,
or the Interrupt Enable Register.
Bit 6 Set Break.
When bit 6 is a 1, the transmit data is forced to the break condition, i.e., space (0) is
sent. When bit 6 is a 0, break is not sent. The Set Break bit acts only on the transmit
data and has no effect on the serial in logic.
Bit 5 Stick Parity.
When parity is enabled (LCR3 = 1) and stick parity is selected (LCR5 = 1), the parity
bit is transmitted and checked by the receiver as a 0 if even parity is selected (LCR4 =
1) or as a 1 if odd parity is selected (LCR4 = 0). When stick parity is not selected
(LCR3 = 0), parity is transmit and checked as determined by the LCR3 and LCR4 bits.
Bit 4 Even Parity Select (EPS).
When parity is enabled (LCR3 = 1) and stick parity is not selected (LCR5 = 0), the
number of 1s transmitted or checked by the receiver in the data word bits and parity bit
is either even (LCR4 = 1) or odd (LCR4 = 0).
Bit 3 Enable Parity (PEN).
When bit 3 is a 1, a parity bit is generated in the serial out (transmit) data stream and
checked in the serial in (receive) data stream as determined by the LCR 4 and LCR5
bits. The parity bit is located between the last data bit and the first stop bit.
Bit 2 Number of Stop Bits (STB).
This bit specifies the number of stop bits in each serial out character. If bit 2 is a 0, one
stop bit is generated regardless of word length. If bit 2 is a 1 and 5-bit word length is
selected, one and one-half stop bits are generated. If bit 2 is a 1 and a 6-, 7-, or 8-bit
word length is selected, two stop bits are generated. The serial in logic checks the first
stop bit only, regardless of the number of stop bits selected.
Bits 1-0 Word Length Select (WLS0 and WLS1).
These two bits specify the number of bits in each serial in or serial out character. The
encoding of bits 0 and 1 is:
Bit 1
Bit 0
Word Length
0
0
5 Bits
0
1
6 Bits
1
0
7 Bits
1
1
8 Bits
CX86500 SCXV.xx Modem Data Sheet
102287H Conexant 4-7
4.2.5 MCR - Modem Control Register (Addr = 4)
The Modem Control Register (MCR) controls the interface with the modem or data set.
Bit 7-5 Not used.
Always 0.
Bit 4 Local Loopback.
When this bit is set to a 1, the diagnostic mode is selected and the following occurs:
Data written to the Transmit Buffer is looped back to the Receiver Buffer.
The DTS (MCR0), RTS (MCR1), Out1 (MCR2), and Out2 (MCR3) modem control
register bits are internally connected to the DSR (MSR5), CTS (MSR4), RI (MSR6), and
DCD (MSR7) modem status register bits, respectively.
Bit 3 Output 2.
When this bit is a 1, HINT is enabled. When this bit is a 0, HINT is in the high
impedance state.
Bit 2 Output 1.
This bit is used in local loopback (see MCR4).
Bit 1 Request to Send (RTS).
This bit controls the Request to Send (RTS) function. When this bit is a 1, RTS is on.
When this bit is a 0, RTS is off.
Bit 0 Data Terminal Ready (DTR).
This bit controls the Data Terminal Ready (DTR) function. When this bit is a 1, DTR is
on. When this bit is a 0, DTR is off.
4.2.6 LSR - Line Status Register (Addr = 5)
This 8-bit register provides status information to the host concerning data transfer.
Bit 7 RX FIFO Error.
In the 16450 mode, this bit is not used and is always 0.
In the FIFO mode, this bit is set if there are one or more characters in the RX FIFO
with a parity error, framing error, or break indication detected. This bit is reset to a 0
when the host reads the LSR and none of the above conditions exist in the RX FIFO.
Bit 6 Transmitter Empty (TEMT).
This bit is set to a 1 whenever the TX Buffer (THR) and equivalent of the Transmitter
Shift Register (TSR) are both empty. It is reset to a 0 whenever either the THR or the
equivalent of the TSR contains a character.
In the FIFO mode, this bit is set to a 1 when ever the TX FIFO and the equivalent of
the TSR are both empty.
CX86500 SCXV.xx Modem Data Sheet
4-8 Conexant 102287H
Bit 5 Transmitter Holding Register Empty (THRE) [TX Buffer Empty].
This bit, when set, indicates that the TX Buffer is empty and the modem can accept a
new character for transmission. In addition, this bit causes the modem to issue an
interrupt to the host when the Transmit Holding Register Empty Interrupt Enable bit
(IIR1) is set to 1. The THRE bit is set to a 1 when a character is transferred from the
TX Buffer. The bit is reset to 0 when a byte is written into the TX Buffer by the host.
In the FIFO mode, this bit is set when the TX FIFO is empty; it is cleared when at least
one byte is in the TX FIFO.
Bit 4 Break Interrupt (BI).
This bit is set to a 1 whenever the received data input is a space (logic 0) for longer
than two full word lengths plus 3 bits. The BI bit is reset when the host reads the LSR.
Bit 3 Framing Error (FE).
This bit indicates that the received character did not have a valid stop bit. The FE bit is
set to a 1 whenever the stop bit following the last data bit or parity bit is detected as a
logic o (space). The FE bit is reset to a 0 when the host reads the LSR.
In the FIFO mode, the error indication is associated with the particular character in the
FIFO it applies to; the FE bit is set to a 1 when this character is loaded into the RX
Buffer.
Bit 2 Parity Error (PE).
This bit indicates that the received data character in the RX Buffer does not have the
correct even or odd parity, as selected by the Even Parity Select bit (LCR4) and the
Stick Parity bit (LCR5). The PE bit is reset to a 0 when the host reads the LSR.
In the FIFO mode, the error indication is associated with the particular character in the
it applies to; the PE bit is set to a 1 when this character is loaded into the RX Buffer.
Bit 1 Overrun Error (OE).
This bit is set to a 1 whenever received data is loaded into the RX Buffer before the
host has read the previous data from the RX Buffer. The OE bit is reset to a 0 when the
host reads the LSR.
In the FIFO mode, if data continues to fill beyond the trigger level, an overrun
condition will occur only if the RX FIFO is full and the next character has been
completely received.
Bit 0 Receiver Data Ready (DR).
This bit is set to a 1 whenever a complete incoming character has been received and
has been transferred into the RX Buffer. The DR bit is reset to a 0 when the host reads
the RX Buffer.
In the FIFO mode, the DR bit is set when the number of received data bytes in the RX
FIFO equals or exceeds the trigger level specified in FCR0-FCR1.
CX86500 SCXV.xx Modem Data Sheet
102287H Conexant 4-9
4.2.7 MSR - Modem Status Register (Addr = 6)
The Modem Status Register (MSR) reports current state and change information of the
modem. Bits 4-7 supply current state and bits 0-3 supply change information. The change
bits are set to a 1 whenever a control input from the modem changes state from the last
MSR read by the host. Bits 0-3 are reset to 0 when the host reads the MSR or upon reset.
Whenever bits 0, 1, 2, or 3 are set to a 1, a Modem Status Interrupt (IIR0-IIR3 = 0) is
generated.
Bit 7 Data Carrier Detect (DCD).
This bit indicates the logic state of the DCD# (RLSD#) output. If Loopback is selected
(MCR4 = 1), this bit reflects the state of the Out2 bit in the MCR (MCR3).
Bit 6 Ring Indicator (RI).
This bit indicates the logic state of the RI# output. If Loopback is selected (MCR4 = 1),
this bit reflects the state of the Out1 bit in the MCR (MCR2).
Bit 5 Data Set Ready (DSR).
This bit indicates the logic state of the DSR# output. If Loopback is selected (MCR4 =
1), this bit reflects the state of the DTR bit in the MCR (MCR0).
Bit 4 Clear to Send (CTS).
This bit indicates the logic state of the CTS# output. If Loopback is selected (MCR4 =
1), this bit reflects the state of the RTS bit in the MCR (MCR1).
Bit 3 Delta Data Carrier Detect (DDCD).
This bit is set to a 1 when the DCD bit changes state since the MSR was last read by
the host.
Bit 2 Trailing Edge of Ring Indicator (TERI).
This bit is set to a 1 when the RI bit changes from a 1 to a 0 state since the MSR was
last read by the host.
Bit 1 Delta Data Set Ready (DDSR).
This bit is set to a 1 when the DSR bit has changed since the MSR was last read by the
host.
Bit 0 Delta Clear to Send (DCTS).
This bit is set to a 1 when the CTS bit has changed since the MSR was last read by the
host.
4.2.8 RBR - RX Buffer (Receiver Buffer Register) (Addr = 0, DLAB = 0)
The RX Buffer (RBR) is a read-only register at location 0 (with DLAB = 0). Bit 0 is the
least significant bit of the data, and is the first bit received.
4.2.9 THR - TX Buffer (Transmitter Holding Register) (Addr = 0, DLAB = 0)
The TX Buffer (THR) is a write-only register at address 0 when DLAB = 0. Bit 0 is the
least significant bit and the first bit sent.
CX86500 SCXV.xx Modem Data Sheet
4-10 Conexant 102287H
4.2.10 Divisor Registers (Addr = 0 and 1, DLAB = 1)
The Divisor Latch LS (least significant byte) and Divisor Latch MS (most significant
byte) are two read-write registers at locations 0 and 1 when DLAB = 1, respectively.
The baud rate is selected by loading each divisor latch with the appropriate hex value.
Programmable values corresponding to the desired baud rate are listed in Table 4-3.
1. SCR - Scratch Register (Addr = 7)
The Scratchpad Register is a read-write register at location 7. This register is not used by
the modem and can be used by the host for temporary storage.
Table 4-3. Programmable Baud Rates
Divisor Latch (Hex)
MS
LS
Divisor (Decimal)
Baud Rate
06
00
1536
75
04
17
1047
110
03
00
768
150
01
80
384
300
00
C0
192
600
00
60
96
1200
00
30
48
2400
00
18
24
4800
00
0C
12
9600
00
06
6
19200
00
04
4
28800
00
03
3
38400
00
02
2
57600
00
01
1
115200
00
00
NA
230400
4.3 Receiver FIFO Interrupt Operation
4.3.1 Receiver Data Available Interrupt
When the FIFO mode is enabled (FCR0 = 1) and receiver interrupt (RX Data Available)
is enabled (IER0 = 1), receiver interrupt operation is as follows:
The Receiver Data Available Flag (LSR0) is set as soon as a received data character is
available in the RX FIFO. LSR0 is cleared when the RX FIFO is empty.
The Receiver Data Available interrupt code (IIR0-IIR4 = 4h) is set whenever the number
of received data bytes in the RX FIFO reaches the trigger level specified by FCR6-FCR7
bits; it is cleared whenever the number of received data bytes in the RX FIFO drops
below the trigger level specified by FCR6-FCR7 bits.
The HINT interrupt is asserted whenever the number of received data bytes in the RX
FIFO reaches the trigger level specified by FCR6-FCR7 bits. HINT interrupt is de-
asserted when the number of received data bytes in the RX FIFO drops below the trigger
level specified by FCR6-FCR7 bits.
CX86500 SCXV.xx Modem Data Sheet
102287H Conexant 4-11
4.3.2 Receiver Character Timeout Interrupts
When the FIFO mode is enabled (FCR0 = 1) and receiver interrupt (Receiver Data
Available) is enabled (IER0 = 1), receiver character timeout interrupt operation is as
follows:
1. A Receiver character timeout interrupt code (IIR0-IIR3 = Ch) is set if at least one
received character is in the RX FIFO, the most recent received serial character was
longer than four continuous character times ago (if 2 stop bits are specified, the
second stop bit is included in this time period), and the most recent host read of the
RX FIFO was longer than four continuous character times ago.
4.4 Transmitter FIFO Interrupt Operation
4.4.1 Transmitter Empty Interrupt
When the FIFO mode is enabled (FCR0 = 1) and transmitter interrupt (TX Buffer Empty)
is enabled (IER0 = 1), transmitter interrupt operation is as follows:
The TX Buffer Empty interrupt code (IIR0-IIR3 = 2h) will occur when the TX Buffer is
empty; it is cleared when the TX Buffer is written to (1 to 16 characters) or the IIR is
read.
The TX Buffer Empty indications will be delayed 1 character time minus the last stop bit
time whenever the following occur: THRE = 1 and there have not been at least two bytes
at the same time in the TX FIFO Buffer since the last setting of THRE was set. The first
transmitter interrupt after setting FCR0 will be immediate.
CX86500 SCXV.xx Modem Data Sheet
4-12 Conexant 102287H
This page is intentionally blank.
CX86500 SCXV.xx Modem Data Sheet
102287H Conexant 5-1
5. Package Dimensions
The 28-pin TSSOP package dimensions are shown in Figure 5-1.
The 38-pin TSSOP package dimensions are shown in Figure 5-2.
The 28-QFN package comes in two packages, either punch or sawn style. Both are
electrically equivalent and share the same footprint. The punch-style package is shown in
Figure 5-3, and the sawn-style package is shown in Figure 5-4. Package dimensions for
both styles are listed in Table 5-1.
The 32-pin LQFP package dimensions are shown in Figure 5-5.
CX86500 SCXV.xx Modem Data Sheet
5-2 Conexant 102287H
Figure 5-1. Package Dimensions - 28-Pin TSSOP
CX86500 SCXV.xx Modem Data Sheet
102287H Conexant 5-3
Figure 5-2. Package Dimensions - 38-Pin TSSOP
CX86500 SCXV.xx Modem Data Sheet
5-4 Conexant 102287H
Figure 5-3. Package Dimensions - 28-Pin QFN: Punch Style
CX86500 SCXV.xx Modem Data Sheet
102287H Conexant 5-5
Figure 5-4. Package Dimensions – 28-Pin QFN: Sawn Style
Table 5-1. Package Dimensions: Punch Style and Sawn Style
CX86500 SCXV.xx Modem Data Sheet
5-6 Conexant 102287H
Figure 5-5. Package Dimensions - 32-Pin LQFP
CX86500 SCXV.xx Modem Data Sheet
102287H Conexant 5-7
This page is intentionally blank.
CX86500 SCXV.xx Modem Data Sheet
102287H Conexant 6-1
6. Recommended TSSOP Surface Mount Land
Pattern
The recommended TSSOP surface mount land pattern based on the IPC-SM-782 standard
for board layout is shown in Figure 6-1.
Figure 6-1. Recommended TSSOP Surface Mount Land Pattern
CX86500 SCXV.xx Modem Data Sheet
6-2 Conexant 102287H
This page is intentionally blank.
NOTES
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