General Description
The MAX7314 I2C-compatible serial interfaced periph-
eral provides microprocessors with 16 I/O ports plus one
output-only port and one input-only port. Each I/O port
can be individually configured as either an open-drain
current-sinking output rated at 50mA and 5.5V, or a logic
input with transition detection. The output-only port can
be assigned as an interrupt output for transition detec-
tion. The outputs are capable of driving LEDs, or provid-
ing logic outputs with external resistive pullup up to 5.5V.
Eight-bit PWM current control is built in for all 17 output
ports. A 4-bit global control applies to all LED outputs
and provides coarse adjustment of current from fully off
to fully on with 14 intensity steps in between. Each out-
put has an individual 4-bit control, which further divides
the globally set current into 16 more steps.
Alternatively, the current control can be configured as a
single 8-bit control that sets all outputs at once.
Each output has independent blink timing with two blink
phases. All LEDs can be individually set to be on or off
during either blink phase, or to ignore the blink control.
The blink period is controlled by a clock input (up to 1kHz)
on BLINK or by a register. The BLINK input can also be
used as a logic control to turn the LEDs on and off, or as a
general-purpose input.
The MAX7314 supports hot insertion. All port pins, the
INT output, SDA, SCL, RST, BLINK, and the slave
address input ADO remain high impedance in power-
down (V+ = 0V) with up to 6V asserted upon them.
The MAX7314 is controlled through a 2-wire serial inter-
face, and uses four-level logic to allow four I2C
addresses from only one select pin.
Applications
LCD Backlights
LED Status Indication
Relay Drivers
Keypad Backlights
RGB LED Drivers
System I/O Ports
Features
♦400kbps, 2-Wire Serial Interface, 5.5V Tolerant
♦2V to 3.6V Operation
♦Overall 8-Bit PWM LED Intensity Control
Global 16-Step Intensity Control
Individual 16-Step Intensity Controls
♦2-Phase LED Blinking
♦50mA Maximum Port Output Current
♦Supports Hot Insertion
♦Outputs are 5.5V-Rated Open Drain
♦Inputs are Overvoltage Protected to 5.5V
♦Transition Detection with Interrupt Output
♦1.2µA (typ), 3.6µA (max) Operating Current
♦Small 4mm x 4mm, Thin QFN Package
♦-40°C to +125°C Temperature Range
MAX7314
18-Port GPIO with LED Intensity Control,
Interrupt, and Hot-Insertion Protection
________________________________________________________________ Maxim Integrated Products 1
MAX7314
P8
P10
P0
P1
P2
P3
P4
P5
P6
P7
V+
3.3V
μC
SDA SDA
AD0
3.3V 5V
P11
P12
P13
P14
P15
SCL
SCL
BLINK
I/O
RST
I/O
P9
OUTPUT
OUTPUT
GND
5V
INPUT 1
INPUT 2
INPUT 3
INPUT 4
INPUT 5
0.047μF
INT INT/O16
Typical Application Circuit
19-3170; Rev 4; 4/05
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
EVALUATION KIT
AVAILABLE
Ordering Information
PART TEMP RANGE PIN-
PACKAGE
PKG
CODE
MAX7314ATG -40°C to +125°C
24 Thin QFN
4mm x 4mm
x 0.8mm
T2444-4
MAX7314AEG -40°C to +125°C 24 QSOP —
Pin Configurations continued at end of data sheet.
MAX7314
18-Port GPIO with LED Intensity Control,
Interrupt, and Hot-Insertion Protection
2 _______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
Voltage (with respect to GND)
V+ .............................................................................-0.3V to +4V
SCL, SDA, AD0, BLINK, RST, P0–P15 .....................-0.3V to +6V
INT/O16 ...................................................................-0.3V to +8V
DC Current on P0–P15, INT/O16 ........................................55mA
DC Current on SDA.............................................................10mA
Maximum GND Current ....................................................350mA
Continuous Power Dissipation (TA= +70°C)
24-Pin QSOP (derate 9.5mW/°C over +70°C)..............761mW
24-Pin QFN (derate 20.8mW/°C over +70°C) ............1666mW
Operating Temperature Range
(TMIN to TMAX) .............................................-40°C to +125°C
Junction Temperature......................................................+150°C
Storage Temperature Range .............................-65°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
ELECTRICAL CHARACTERISTICS
(Typical Operating Circuit, V+ = 2V to 3.6V, TA= TMIN to TMAX, unless otherwise noted. Typical values are at V+ = 3.3V, TA = +25°C.)
(Note 1)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
Operating Supply Voltage V+ 2 3.6 V
Output Load External Supply
Voltage VEXT 0 5.5 V
TA = +25°C 1.2 2.3
TA = -40°C to +85°C 2.8
Standby Current
(Interface Idle, PWM Disabled) I+
S C L and S D A at V + ; other
d i g i tal i np uts at V + or GN D ;
P WM i ntensi ty contr ol d i sab l ed TA = TMIN to TMAX 3.6
µA
TA = +25°C 8.5 15.1
TA = -40°C to +85°C 16.5
Supply Current
(Interface Idle, PWM Enabled) I+
S C L and S D A at V + ; other
d i g i tal i np uts at V + or GN D ;
P WM i ntensi ty contr ol d i sab l ed TA = TMIN to TMAX 17.2
µA
TA = +25°C 50 95.3
TA = -40°C to +85°C 99.2
Supply Current
(Interface Running, PWM
Disabled)
I+
fSCL = 400kHz; other digital
inputs at V+ or GND; PWM
intensity control enabled TA = TMIN to TMAX 102.4
µA
TA = +25°C 57 110.2
TA = -40°C to +85°C 117.4
Supply Current
(Interface Running, PWM
Enabled)
I+
fSCL = 400kHz; other digital
inputs at V+ or GND; PWM
intensity control enabled TA = TMIN to TMAX 122.1
µA
Input High Voltage
SDA, SCL, AD0, BLINK, P0–P15 VIH 0.7 x
V+ V
Input Low Voltage
SDA, SCL, AD0, BLINK, P0–P15 VIL 0.3 x
V+ V
Input Leakage Current
SDA, SCL, AD0, BLINK, P0–P15 IIH, IIL 0 ≤ input voltage ≤ 5.5V -0.2 +0.2 µA
Input Capacitance
SDA, SCL, AD0, BLINK, P0–P15 8pF
MAX7314
18-Port GPIO with LED Intensity Control,
Interrupt, and Hot-Insertion Protection
_______________________________________________________________________________________ 3
ELECTRICAL CHARACTERISTICS (continued)
(Typical Operating Circuit, V+ = 2V to 3.6V, TA= TMIN to TMAX, unless otherwise noted. Typical values are at V+ = 3.3V, TA= + 25°C.)
(Note 1)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
TA = +25°C 0.15 0.26
TA = -40°C to +85°C 0.3
V+ = 2V, ISINK = 20mA
TA = TMIN to TMAX 0.32
V
TA = +25°C 0.13 0.23
TA = -40°C to +85°C 0.26V+ = 2.5V, ISINK = 20mA
TA = TMIN to TMAX 0.28
V
TA = +25°C 0.12 0.23
TA = -40°C to +85°C 0.24
Output Low Voltage
P0–P15, INT/O16 VOL
V+ = 3.3V, ISINK = 20mA
TA = TMIN to TMAX 0.26
V
Output Low-Voltage SDA VOLSDA ISINK = 6mA 0.4 V
PWM Clock Frequency fPWM 32 kHz
TIMING CHARACTERISTICS
(Typical Operating Circuit, V+ = 2V to 3.6V, TA= TMIN to TMAX, unless otherwise noted. Typical values are at V+ = 3.3V, TA = +25°C.)
(Note 1)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
Serial Clock Frequency fSCL 400 kHz
Bus Free Time Between a STOP and a START
Condition tBUF 1.3 µs
Hold Time, Repeated START Condition tHD
,
STA 0.6 µs
Repeated START Condition Setup Time tSU
,
STA 0.6 µs
STOP Condition Setup Time tSU
,
STO 0.6 µs
Data Hold Time tHD
,
DAT (Note 2) 0.9 µs
Data Setup Time tSU
,
DAT 180 ns
SCL Clock Low Period tLOW 1.3 µs
SCL Clock High Period tHIGH 0.7 µs
Rise Time of Both SDA and SCL Signals, Receiving tR(Notes 3, 4) 20 +
0.1Cb300 ns
Fall Time of Both SDA and SCL Signals, Receiving tF(Notes 3, 4) 20 +
0.1Cb300 ns
Fall Time of SDA Transmitting tF.TX (Notes 3, 5) 20 +
0.1Cb250 ns
Pulse Width of Spike Suppressed tSP (Note 6) 50 ns
Capacitive Load for Each Bus Line Cb(Note 3) 400 pF
RST Pulse Width tW1µs
MAX7314
18-Port GPIO with LED Intensity Control,
Interrupt, and Hot-Insertion Protection
4 _______________________________________________________________________________________
TIMING CHARACTERISTICS (continued)
(Typical Operating Circuit, V+ = 2V to 3.6V, TA= TMIN to TMAX, unless otherwise noted. Typical values are at V+ = 3.3V, TA = +25°C.)
(Note 1)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
Interrupt Valid tIV Figure 10 6.5 µs
Interrupt Reset tIR Figure 10 1 µs
Output Data Valid tDV Figure 10 5 µs
Input Data Set-Up Time tDS Figure 10 100 ns
Input Data Hold Time tDH Figure 10 1 µs
Note 1: All parameters tested at TA= +25°C. Specifications over temperature are guaranteed by design.
Note 2: A master device must provide a hold time of at least 300ns for the SDA signal (referred to VIL of the SCL signal) to bridge
the undefined region of SCL’s falling edge.
Note 3: Guaranteed by design.
Note 4: Cb= total capacitance of one bus line in pF. tRand tFmeasured between 0.3 x VDD and 0.7 x VDD.
Note 5: ISINK ≤6mA. Cb= total capacitance of one bus line in pF. tRand tFmeasured between 0.3 x VDD and 0.7 x VDD.
Note 6: Input filters on the SDA and SCL inputs suppress noise spikes less than 50ns.
STANDBY CURRENT vs. TEMPERATURE
MAX7314 toc01
TEMPERATURE (°C)
STANDBY CURRENT (μA)
1109565 80-10 5 20 35 50-25
1
2
3
4
5
6
7
8
9
10
0
-40 125
V+ = 3.6V
PWM ENABLED
V+ = 2.7V
PWM ENABLED
V+ = 2V
PWM DISABLED
V+ = 2.7V
PWM DISABLED
V+ = 3.6V
PWM
DISABLED
V+ = 2V
PWM ENABLED
SUPPLY CURRENT vs. TEMPERATURE
(PWM DISABLED; fSCL = 400kHz)
MAX7314 toc02
TEMPERATURE (°C)
SUPPLY CURRENT (μA)
1109565 80-10 5 20 35 50-25
10
20
30
40
50
60
70
0
-40 125
V+ = 3.6V
V+ = 2.7V
V+ = 2V
5
10
15
20
25
30
35
40
45
50
55
60
65
70
0
SUPPLY CURRENT vs. TEMPERATURE
(PWM ENABLED; fSCL = 400kHz)
MAX7314 toc03
TEMPERATURE (°C)
SUPPLY CURRENT (μA)
1109565 80-10 5 20 35 50-25-40 125
V+ = 3.6V
V+ = 2.7V
V+ = 2V
__________________________________________Typical Operating Characteristics
(TA = +25°C, unless otherwise noted.)
MAX7314
18-Port GPIO with LED Intensity Control,
Interrupt, and Hot-Insertion Protection
_______________________________________________________________________________________ 5
PORT OUTPUT LOW VOLTAGE WITH 50mA
LOAD CURRENT vs. TEMPERATURE
PORT OUTPUT LOW VOLTAGE VOL (V)
0.1
0.2
0.3
0.4
0.5
0.6
0
MAX7314 toc04
TEMPERATURE (°C)
1109565 80-10 5 20 35 50-25-40 125
V+ = 3.6V
V+ = 2.7V
V+ = 2V
PORT OUTPUT LOW VOLTAGE WITH 20mA
LOAD CURRENT vs. TEMPERATURE
MAX7314 toc05
TEMPERATURE (°C)
PORT OUTPUT LOW VOLTAGE VOL (V)
1109580655035205-10-25
0.1
0.2
0.3
0.4
0.5
0.6
0
-40 125
ALL OUTPUTS LOADED
V+ = 3.6V
V+ = 2.7V
V+ = 2V
PWM CLOCK FREQUENCY
vs. TEMPERATURE
MAX7314 toc06
TEMPERATURE (°C)
PWM CLOCK FREQUENCY (kHz)
1109580655035205-10-25
0.950
1.000
1.050
0.900
0.925
0.975
1.025
-40 125
V+ = 3.6V
V+ = 2V
V+ = 2.7V
NORMALIZED TO V+ = 3.3V, TA = +25°C
SCOPE SHOT OF 2 OUTPUT PORTS
MAX7314 toc07
2ms/div
OUTPUT 1,
2V/div
OUTPUT 2,
2V/div
MASTER INTENSITY SET TO 1/15
OUTPUT 1 INDIVIDUAL INTENSITY
SET TO 1/16
OUTPUT 2 INDIVIDUAL INTENSITY
SET TO 15/16
SCOPE SHOT OF 2 OUTPUT PORTS
MAX7314 toc08
2ms/div
OUTPUT 1
2V/div
OUTPUT 2
2V/div
OUTPUT 1 INDIVIDUAL INTENSITY
SET TO 1/16
MASTER INTENSITY SET TO 14/15
OUTPUT 2 INDIVIDUAL INTENSITY
SET TO 14/15
MAX7314 toc09
SINK CURRENT vs. VOL
SINK CURRENT (mA)
VOL (V)
5040302010
0.05
0.10
0.15
0.20
0.25
0.30
0.35
0
0453525155
V+ = 2V
V+ = 2.7V
ONLY ONE OUTPUT LOADED
V+ = 3.3V
V+ = 3.6V
Typical Operating Characteristics (continued)
(TA = +25°C, unless otherwise noted.)
MAX7314
Functional Overview
The MAX7314 is a general-purpose input/output (GPIO)
peripheral that provides 16 I/O ports, P0–P15, con-
trolled through an I2C-compatible serial interface. A
17th output-only port, INT/O16, can be configured as
an interrupt output or as a general-purpose output port.
All output ports sink loads up to 50mA connected to
external supplies up to 5.5V, independent of the
MAX7314’s supply voltage. The MAX7314 is rated for a
ground current of 350mA, allowing all 17 outputs to sink
20mA at the same time. Figure 1 shows the output
structure of the MAX7314. The ports default to inputs on
power-up.
18-Port GPIO with LED Intensity Control,
Interrupt, and Hot-Insertion Protection
6 _______________________________________________________________________________________
Pin Description
Figure 1. Simplified Schematic of I/O Ports
D
CK
Q
Q
FF
DATA FROM
SHIFT REGISTER
DATA FROM
SHIFT REGISTER
WRITE
CONFIGURATION
PULSE
WRITE PULSE
READ PULSE
CONFIGURATION
REGISTER
D
CK
Q
Q
FF
INPUT PORT
REGISTER
D
CK
Q
Q
FF
OUTPUT
PORT
REGISTER
OUTPUT PORT
REGISTER DATA
I/O PIN
Q2
GND
INPUT PORT
REGISTER DATA
TO INT
PIN
QSOP QFN NAME FUNCTION
122INT/O16 Output Port. Open-drain output rated at 7V, 50mA. Configurable as interrupt
output or general-purpose output.
223RST Reset Input. Active low clears the 2-wire interface and puts the device in the
same condition as power-up reset.
3 24 AD0 Address Input. Sets device slave address. Connect to either GND, V+, SCL,
or SDA to give four logic combinations. See Table 1.
4–11, 13–20 1–8, 10–17 P0–P15 Input/Output Ports. P0–P15 are open-drain I/Os rated at 5.5V, 50mA.
12 9 GND Ground. Do not sink more than 350mA into the GND pin.
21 18 BLINK Input Port Configurable as Blink Control or General-Purpose Input
22 19 SCL I2C-Compatible Serial Clock Input
23 20 SDA I2C-Compatible Serial Data I/O
24 21 V+ Positive Supply Voltage. Bypass V+ to GND with a 0.047µF ceramic
capacitor.
— PAD Exposed Pad Exposed Pad on Package Underside. Connect to GND.
Port Inputs and Transition Detection
Input ports registers reflect the incoming logic levels of
the port pins, regardless of whether the pin is defined
as an input or an output. Reading an input ports regis-
ter latches the current-input logic level of the affected
eight ports. Transition detection allows all ports config-
ured as inputs to be monitored for changes in their
logic status. The action of reading an input ports regis-
ter samples the corresponding 8 port bits’ input condi-
tion. This sample is continuously compared with the
actual input conditions. A detected change in input
condition causes the INT/O16 interrupt output to go
low, if configured as an interrupt output. The interrupt is
cleared either automatically if the changed input
returns to its original state, or when the appropriate
input ports register is read.
The INT/O16 pin can be configured as either an inter-
rupt output or as a 17th output port with the same static
or blink controls as the other 16 ports (Table 4).
Port Output Control and LED Blinking
The two blink phase 0 registers set the output logic lev-
els of the 16 ports P0–P15 (Table 8). These registers
control the port outputs if the blink function is disabled.
A duplicate pair of registers, the blink phase 1 registers,
are also used if the blink function is enabled (Table 9).
In blink mode, the port outputs can be flipped between
using the blink phase 0 registers and the blink phase 1
registers using hardware control (the BLINK input)
and/or software control (the blink flip flag in the configu-
ration register) (Table 4). The logic level of the BLINK
input can be read back through the blink status bit in
the configuration register (Table 4). The BLINK input,
therefore, can be used as a general-purpose logic input
(GPI port) if the blink function is not required.
PWM Intensity Control
The MAX7314 includes an internal oscillator, nominally
32kHz, to generate PWM timing for LED intensity control.
PWM intensity control can be enabled on an output-by-
output basis, allowing the MAX7314 to provide any mix
of PWM LED drives and glitch-free logic outputs (Table
10). PWM can be disabled entirely, in which case all out-
put ports are static and the MAX7314 operating current
is lowest because the internal oscillator is turned off.
PWM intensity control uses a 4-bit master control and 4
bits of individual control per output (Tables 13, 14). The
4-bit master control provides 16 levels of overall intensi-
ty control, which applies to all PWM-enabled output
ports. The master control sets the maximum pulse
width from 1/15 to 15/15 of the PWM time period. The
individual settings comprise a 4-bit number, further
reducing the duty cycle to be from 1/16 to 15/16 of the
time window set by the master control.
For applications requiring the same PWM setting for all
output ports, a single global PWM control can be used
instead of all the individual controls to simplify the con-
trol software and provide 240 steps of intensity control
(Tables 10 and 13).
Standby Mode
When the serial interface is idle and the PWM intensity
control is unused, the MAX7314 automatically enters
standby mode. If the PWM intensity control is used, the
operating current is slightly higher because the internal
PWM oscillator is running. When the serial interface is
active, the operating current also increases because
the MAX7314, like all I2C slaves, has to monitor every
transmission.
MAX7314
18-Port GPIO with LED Intensity Control,
Interrupt, and Hot-Insertion Protection
_______________________________________________________________________________________ 7
Figure 2. 2-Wire Serial Interface Timing Details
SCL
SDA
tRtF
tBUF
START
CONDITION
STOP
CONDITION
REPEATED START CONDITION
START CONDITION
tSU,STO
tHD,STA
tSU,STA
tHD,DAT
tSU,DAT
tLOW
tHIGH
tHD,STA
MAX7314
Serial Interface
Serial Addressing
The MAX7314 operates as a slave that sends and
receives data through an I2C-compatible 2-wire inter-
face. The interface uses a serial data line (SDA) and a
serial clock line (SCL) to achieve bidirectional commu-
nication between master(s) and slave(s). A master (typ-
ically a microcontroller) initiates all data transfers to and
from the MAX7314 and generates the SCL clock that
synchronizes the data transfer (Figure 2).
The MAX7314 SDA line operates as both an input and
an open-drain output. A pullup resistor, typically 4.7kΩ,
is required on the SDA. The MAX7314 SCL line oper-
ates only as an input. A pullup resistor, typically 4.7kΩ,
is required on SCL if there are multiple masters on the
2-wire interface, or if the master in a single-master sys-
tem has an open-drain SCL output.
Each transmission consists of a START condition
(Figure 3) sent by a master, followed by the MAX7314
7-bit slave address plus R/Wbit, a register address
byte, one or more data bytes, and finally a STOP condi-
tion (Figure 3).
Start and Stop Conditions
Both SCL and SDA remain high when the interface is
not busy. A master signals the beginning of a transmis-
sion with a START (S) condition by transitioning SDA
from high to low while SCL is high. When the master
has finished communicating with the slave, it issues a
STOP (P) condition by transitioning SDA from low to
high while SCL is high. The bus is then free for another
transmission (Figure 3).
Bit Transfer
One data bit is transferred during each clock pulse.
The data on SDA must remain stable while SCL is high
(Figure 4).
Acknowledge
The acknowledge bit is a clocked 9th bit that the recipi-
ent uses to handshake receipt of each byte of data
(Figure 5). Thus, each byte transferred effectively
requires 9 bits. The master generates the 9th clock
pulse, and the recipient pulls down SDA during the
acknowledge clock pulse so the SDA line is stable low
during the high period of the clock pulse. When the
master is transmitting to the MAX7314, the device gen-
erates the acknowledge bit because the MAX7314 is
the recipient. When the MAX7314 is transmitting to the
master, the master generates the acknowledge bit
because the master is the recipient.
Slave Address
The MAX7314 has a 7-bit long slave address (Figure 6).
The eighth bit following the 7-bit slave address is the
R/Wbit. The R/Wbit is low for a write command, high
for a read command.
18-Port GPIO with LED Intensity Control,
Interrupt, and Hot-Insertion Protection
8 _______________________________________________________________________________________
Figure 3. Start and Stop Conditions
SDA
SCL
START
CONDITION
STOP
CONDITION
SP
Figure 4. Bit Transfer
SDA
SCL
DATA LINE STABLE;
DATA VALID
CHANGE OF DATA
ALLOWED
Figure 5. Acknowledge
SCL
SDA BY
TRANSMITTER
CLOCK PULSE
FOR ACKNOWLEDGE
START
CONDITION
SDA BY
RECEIVER
12 89
S
Figure 6. Slave Address
SDA
SCL
1
MSB LSB
ACK00A6 0 0A2 R/W
The second (A5), third (A4), fourth (A3), sixth (A1), and
last (A0) bits of the MAX7314 slave address are always
1, 0, 0, 0, and 0. Slave address bits A6 and A2 are
selected by the address input AD0. AD0 can be con-
nected to GND, V+, SDA, or SCL. The MAX7314 has four
possible slave addresses (Table 1), and therefore a
maximum of four MAX7314 devices can be controlled
independently from the same interface.
Message Format for Writing the MAX7314
A write to the MAX7314 comprises the transmission of
the MAX7314’s slave address with the R/Wbit set to
zero, followed by at least 1 byte of information. The first
byte of information is the command byte. The com-
mand byte determines which register of the MAX7314
is to be written to by the next byte, if received (Table 2).
If a STOP condition is detected after the command byte
is received, then the MAX7314 takes no further action
beyond storing the command byte.
Any bytes received after the command byte are data
bytes. The first data byte goes into the internal register
of the MAX7314 selected by the command byte (Figure
8). If multiple data bytes are transmitted before a STOP
condition is detected, these bytes are generally stored
in subsequent MAX7314 internal registers because the
command byte address autoincrements (Table 2). A
diagram of a write to the output ports registers (blink
phase 0 registers or blink phase 1 registers) is given in
Figure 10.
MAX7314
18-Port GPIO with LED Intensity Control,
Interrupt, and Hot-Insertion Protection
_______________________________________________________________________________________ 9
Table 1. MAX7314 Address Map
DEVICE ADDRESS
PIN AD0 A6 A5 A4 A3 A2 A1 A0
SCL1100000
SDA1100100
GND0100000
V+ 0100100
Figure 8. Command and Single Data Byte Received
SAAAP0SLAVE ADDRESS COMMAND BYTE DATA BYTE
1
BYTE
AUTOINCREMENT MEMORY ADDRESS
D15 D14 D13 D12 D11 D10 D9 D8 D1 D0D3 D2D5 D4D7 D6
ACKNOWLEDGE FROM MAX7314 ACKNOWLEDGE FROM MAX7314
ACKNOWLEDGE FROM MAX7314
HOW COMMAND BYTE AND DATA BYTE MAP INTO
MAX7314's REGISTERS
R/W
Figure 9. n Data Bytes Received
SAAAP0SLAVE ADDRESS COMMAND BYTE DATA BYTE
N
BYTES
AUTOINCREMENT MEMORY ADDRESS
D15 D14 D13 D12 D11 D10 D9 D8 D1 D0D3 D2D5 D4D7 D6
ACKNOWLEDGE FROM MAX7314 ACKNOWLEDGE FROM MAX7314
ACKNOWLEDGE FROM MAX7314
HOW COMMAND BYTE AND DATA BYTE MAP INTO
MAX7314's REGISTERS
R/W
Figure 7. Command Byte Received
SAAP0SLAVE ADDRESS COMMAND BYTE
ACKNOWLEDGE FROM MAX7314
D15 D14 D13 D12 D11 D10 D9 D8
COMMAND BYTE IS STORED ON RECEIPT OF
STOP CONDITION
ACKNOWLEDGE FROM MAX7314
R/W
MAX7314
Message Format for Reading
The MAX7314 is read using the MAX7314’s internally
stored command byte as an address pointer the same
way the stored command byte is used as an address
pointer for a write. The pointer autoincrements after
each data byte is read using the same rules as for a
write (Table 2). Thus, a read is initiated by first configur-
ing the MAX7314’s command byte by performing a
write (Figure 7). The master can now read n consecu-
tive bytes from the MAX7314 with the first data byte
being read from the register addressed by the initial-
ized command byte. When performing read-after-write
verification, remember to reset the command byte’s
address because the stored command byte address
has been autoincremented after the write (Table 2). A
diagram of a read from the input ports registers is
shown in Figure 10 reflecting the states of the ports.
Operation with Multiple Masters
If the MAX7314 is operated on a 2-wire interface with
multiple masters, a master reading the MAX7314 should
use a repeated start between the write, which sets the
MAX7314’s address pointer, and the read(s) that takes
the data from the location(s) (Table 2). This is because it
is possible for master 2 to take over the bus after master
1 has set up the MAX7314’s address pointer but before
master 1 has read the data. If master 2 subsequently
changes the MAX7314’s address pointer, then master
1’s delayed read can be from an unexpected location.
Command Address Autoincrementing
The command address stored in the MAX7314 circu-
lates around grouped register functions after each data
byte is written or read (Table 2).
18-Port GPIO with LED Intensity Control,
Interrupt, and Hot-Insertion Protection
10 ______________________________________________________________________________________
Figure 10. Read, Write, and Interrupt Timing Diagrams
SLAVE ADDRESS
123456789
SA6A5A4A3A2A1A00 A0 000000
COMMAND BYTE
1A A AP
START CONDITION ACKNOWLEDGE FROM SLAVE ACKNOWLEDGE FROM SLAVE ACKNOWLEDGE FROM SLAVE STOP
CONDITION
P7–P0
P15– P8
DATA1 VALID
DATA2 VALID
SLAVE ADDRESS
123456789
S A6A5A4A3A2A1A0 1 A
COMMAND BYTE
ANA
START CONDITION ACKNOWLEDGE FROM SLAVE ACKNOWLEDGE FROM MASTER
P7–P0
P15–P8
STOP CONDITION
P
NO ACKNOWLEDGE FROM
MASTER
DATA2
DATA4DATA3
tDV
tDV
SLAVE ADDRESS
123456789
SA6A5A4A3A2A1A0 1 A
COMMAND BYTE
ANA
START CONDITION ACKNOWLEDGE FROM SLAVE ACKNOWLEDGE FROM MASTER
P7–P0
P15–P8
STOP CONDITION
P
NO ACKNOWLEDGE FROM
MASTER
DATA1 DATA2 DATA3 DATA4
DATA6DATA5
tDH
tDS
DATA1
tIV
tIR tIR
tIV
SCL
SDA
SCL
SDA
SCL
SDA
WRITE TO OUTPUT PORTS REGISTERS (BLINK PHASE 0 REGISTERS/BLINK PHASE 1 REGISTERS)
READ FROM INPUT PORTS REGISTERS
INTERRUPT VALID/RESET
R/W
MSB LSBDATA1
MSB LSBDATA1
MSB LSBDATA2 MSB LSBDATA4
MSB LSBDATA6
MSB LSBDATA2
R/W
R/W
INT
Device Reset
The reset input RST is an active-low input. When taken
low, RST clears any transaction to or from the MAX7314
on the serial interface and configures the internal regis-
ters to the same state as a power-up reset (Table 3),
which resets all ports as inputs. The MAX7314 then
waits for a START condition on the serial interface.
Detailed Description
Initial Power-Up
On power-up, and whenever the RST input is pulled
low, all control registers are reset and the MAX7314
enters standby mode (Table 3). Power-up status makes
all ports into inputs and disables both the PWM oscilla-
tor and blink functionality. RST can be used as a hard-
ware shutdown input, which effectively turns off any
LED (or other) loads and puts the device into its lowest
power condition.
Configuration Register
The configuration register is used to configure the PWM
intensity mode, interrupt, and blink behavior, operate
the INT/O16 output, and read back the interrupt status
(Table 4).
Ports Configuration
The 16 I/O ports P0 through P15 can be configured to
any combination of inputs and outputs using the ports
configuration registers (Table 5). The INT/O16 output
can also be configured as an extra general-purpose
output, and the BLINK input can be configured as an
extra general-purpose input using the configuration
register (Table 4).
Input Ports
The input ports registers are read only (Table 6). They
reflect the incoming logic levels of the ports, regardless of
whether the port is defined as an input or an output by the
ports configuration registers. Reading an input ports reg-
ister latches the current-input logic level of the affected
eight ports. A write to an input ports register is ignored.
MAX7314
18-Port GPIO with LED Intensity Control,
Interrupt, and Hot-Insertion Protection
______________________________________________________________________________________ 11
Table 2. Register Address Map
REGISTER ADDRESS CODE
(hex)
AUTOINCREMENT
ADDRESS
Read input ports P7–P0 0x00 0x01
Read input ports P15–P8 0x01 0x00
Blink phase 0 outputs P7–P0 0x02 0x03
Blink phase 0 outputs P15–P8 0x03 0x02
Ports configuration P7–P0 0x06 0x07
Ports configuration P15–P8 0x07 0x06
Blink phase 1 outputs P7–P0 0x0A 0x0B
Blink phase 1 outputs P15–P8 0x0B 0x0A
Master, O16 intensity 0x0E 0x0E (no change)
Configuration 0x0F 0x0F (no change)
Outputs intensity P1, P0 0x10 0x11
Outputs intensity P3, P2 0x11 0x12
Outputs intensity P5, P4 0x12 0x13
Outputs intensity P7, P6 0x13 0x14
Outputs intensity P9, P8 0x14 0x15
Outputs intensity P11, P10 0x15 0x16
Outputs intensity P13, P12 0x16 0x17
Outputs intensity P15, P14 0x17 0x10
MAX7314
Transition Detection
All ports configured as inputs are always monitored for
changes in their logic status. The action of reading an
input ports register or writing to the configuration regis-
ter samples the corresponding 8 port bits’ input condi-
tion (Tables 4, 6). This sample is continuously
compared with the actual input conditions. A detected
change in input condition causes an interrupt condition.
The interrupt is cleared either automatically if the
changed input returns to its original state, or when the
appropriate input ports register is read, updating the
compared data (Figure 10). Randomly changing a port
from an output to an input may cause a false interrupt
to occur if the state of the input does not match the
content of the appropriate input ports register. The
interrupt status is available as the interrupt flag INT in
the configuration register (Table 4).
The input status of all ports is sampled immediately
after power-up as part of the MAX7314’s internal initial-
ization, so if all the ports are pulled to valid logic levels
at that time, an interrupt does not occur at power-up.
INT
/O16 Output
The INT/O16 output pin can be configured as either the
INT output that reflects the interrupt flag logic state or as
a general-purpose output O16. When used as a general-
purpose output, the INT/O16 pin has the same blink and
PWM intensity control capabilities as the other ports.
Set the interrupt enable I bit in the configuration register
to configure INT/O16 as the INT output (Table 4). Clear
interrupt enable to configure INT/O16 as the O16. The
O16 logic state is set by the 2 bits O1 and O0 in the
configuration register. O16 follows the rules for blinking
selected by the blink enable flag E in the configuration
register. If blinking is disabled, then interrupt output
control O0 alone sets the logic state of the INT/O16 pin.
If blinking is enabled, then both interrupt output con-
trols O0 and O1 set the logic state of the INT/O16 pin
according to the blink phase. PWM intensity control for
O16 is set by the 4 global intensity bits in the master
and O16 intensity register (Table 13).
18-Port GPIO with LED Intensity Control,
Interrupt, and Hot-Insertion Protection
12 ______________________________________________________________________________________
Table 3. Power-Up Configuration
REGISTER DATA
REGISTER FUNCTION POWER-UP CONDITION
ADDRESS
CODE
(hex) D7 D6 D5 D4 D3 D2 D1 D0
Blink phase 0 outputs P7–P0 High-impedance outputs 0x02 1 1 1 1 1 1 1 1
Blink phase 0 outputs P15–P8 High-impedance outputs 0x03 1 1 1 1 1 1 1 1
Ports configuration P7–P0 Ports P7–P0 are inputs 0x06 1 1 1 1 1 1 1 1
Ports configuration P15–P8 Ports P15–P8 are inputs 0x07 1 1 1 1 1 1 1 1
Blink phase 1 outputs P7–P0 High-impedance outputs 0x0A 1 1 1 1 1 1 1 1
Blink phase 1 outputs P15–P8 High-impedance outputs 0x0B 1 1 1 1 1 1 1 1
Master, O16 intensity PWM oscillator is disabled;
O16 is static logic output 0x0E 0 0 0 0 1 1 1 1
Configuration
INT/O16 is interrupt output;
blink is disabled;
global intensity is enabled
0x0F 0 0 0 0 1 1 0 0
Outputs intensity P1, P0 P1, P0 are static logic outputs 0x10 1 1 1 1 1 1 1 1
Outputs Intensity P3, P2 P3, P2 are static logic outputs 0x11 1 1 1 1 1 1 1 1
Outputs intensity P5, P4 P5, P4 are static logic outputs 0x12 1 1 1 1 1 1 1 1
Outputs intensity P7, P6 P7, P6 are static logic outputs 0x13 1 1 1 1 1 1 1 1
Outputs intensity P9, P8 P9, P8 are static logic outputs 0x14 1 1 1 1 1 1 1 1
Outputs intensity P11, P10 P11, P10 are static logic outputs 0x15 1 1 1 1 1 1 1 1
Outputs intensity P13, P12 P13, P12 are static logic outputs 0x16 1 1 1 1 1 1 1 1
Outputs intensity P15, P14 P15, P14 are static logic outputs 0x17 1 1 1 1 1 1 1 1
MAX7314
18-Port GPIO with LED Intensity Control,
Interrupt, and Hot-Insertion Protection
______________________________________________________________________________________ 13
Table 4. Configuration Register
REGISTER DATA
REGISTER
ADDRESS
CODE
(hex) D7 D6 D5 D4 D3 D2 D1 D0
CONFIGURATION
R/W
0x0F
INTERRUPT
STATUS
BLINK
STATUS
INTERRUPT
OUTPUT
CONTROL
AS GPO
INTERRUPT
ENABLE
GLOBAL
INTENSITY
BLINK FLIP
BLINK
ENABLE
Write device configuration
0
Read back device configuration
1
INT BLINK O1
O0 I G B E
Disable blink
—
XXXXXXX0
Enable blink
—
XXXXXXX1
—
XXXXXX01
Flip blink register (see text)
—
XXXXXX11
Disable global intensity control—intensity
is set by registers 0x10–0x17 for ports P0
through P15 when configured as outputs,
and by D3–D0 of register 0x0E for
INT/O16 when INT/O16 pin is configured
as an output port
—
XXXXX0XX
Enable global intensity control—intensity
for all ports configured as outputs is set
by D3–D0 of register 0x0E
—
XXXXX1XX
Disable data change interrupt—INT/O16
output is controlled by the O0 and O1 bits
—
XXXX0XXX
Enable data change interrupt—INT/O16
output is controlled by port input data
change
—
XXXX1XXX
INT/O16 output is low (blink is disabled)
—
XXX00XX0
INT/O16 output is high impedance (blink
is disabled)
—
XXX10XX0
INT/O16 outp ut i s l ow d ur i ng b l i nk p hase 0
—
XXX00XX1
INT/O16 output is high impedance during
blink phase 0
—
XXX10XX1
INT/O16 outp ut i s l ow d ur i ng b l i nk p hase 1
—
XX0X0XX1
INT/O16 output is high impedance during
blink phase 1
—
XX1X0XX1
X = Don’t care.
MAX7314
Blink Mode
In blink mode, the output ports can be flipped between
using either the blink phase 0 registers or the blink
phase 1 registers. Flip control is both hardware (the
BLINK input) and software control (the blink flip flag B
in the configuration register) (Table 4).
The blink function can be used for LED effects by pro-
gramming different display patterns in the two sets of
output port registers, and using the software or hard-
ware controls to flip between the patterns.
If the blink phase 1 registers are written with 0xFF, then
the BLINK input can be used as a hardware disable to,
for example, instantly turn off an LED pattern pro-
grammed into the blink phase 0 registers. This tech-
nique can be further extended by driving the BLINK
input with a PWM signal to modulate the LED current to
provide fading effects.
The blink mode is enabled by setting the blink enable flag
E in the configuration register (Table 4). When blink mode
is enabled, the states of the blink flip flag and the BLINK
input are EXOR’ed to set the phase, and the output ports
are set by either the blink phase 0 registers or the blink
phase 1 registers (Figure 11) (Table 7).
The blink mode is disabled by clearing the blink enable
flag E in the configuration register (Table 4). When blink
mode is disabled, the state of the blink flip flag is
ignored, and the blink phase 0 registers alone control
the output ports.
Blink Phase Registers
When the blink function is disabled, the two blink phase
0 registers set the logic levels of the 16 ports (P0
through P15) when configured as outputs (Table 8). A
duplicate pair of registers called the blink phase 1 reg-
isters are also used if the blink function is enabled (Table
9). A logic high sets the appropriate output port high
impedance, while a logic low makes the port go low.
18-Port GPIO with LED Intensity Control,
Interrupt, and Hot-Insertion Protection
14 ______________________________________________________________________________________
Table 4. Configuration Register (continued)
REGISTER DATA
REGISTER
ADDRESS
CODE
(hex) D7 D6 D5 D4 D3 D2 D1 D0
CONFIGURATION
R/W
INTERRUPT
STATUS
BLINK
STATUS
INTERRUPT
OUTPUT
CONTROL
AS GPO
INTERRUPT
ENABLE
GLOBAL
INTENSITY
BLINK FLIP
BLINK
ENABLE
Write device configuration
0
Read back device configuration
1
INT BLINK O1 O0
IGBE
Read back BLINK input pin status—
input is low
1
X0XXXXXX
Read back BLINK input pin status—
input is high
1
X1XXXXXX
Read b ack d ata chang e i nter r up t status
— d ata chang e i s not d etected , and
INT/O16 outp ut i s hi g h w hen i nter r up t
enab l e ( I b i t) i s set
1
0XXXXXXX
Read b ack d ata chang e i nter r up t status
—d ata chang e i s d etected , and INT/O16
outp ut i s l ow w hen i nter r up t enab l e ( I b i t) i s set
1
0x0F
1XXXXXXX
X = Don’t care.
BLINK PHASE REGISTERS
BLINK INPUT
BLINK FLIP FLAG B
BLINK ENABLE FLAG E
Figure 11. Blink Logic
Reading a blink phase register reads the value stored
in the register, not the actual port condition. The port
output itself may or may not be at a valid logic level,
depending on the external load connected.
The 17th output, O16, is controlled through 2 bits in the
configuration register, which provide the same static or
blink control as the other 16 output ports.
PWM Intensity Control
The MAX7314 includes an internal oscillator, nominally
32kHz, to generate PWM timing for LED intensity con-
trol or other applications such as PWM trim DACs.
PWM can be disabled entirely for all the outputs. In this
case, all outputs are static and the MAX7314 operating
current is lowest because the internal PWM oscillator is
turned off.
The MAX7314 can be configured to provide any combi-
nation of PWM outputs and glitch-free logic outputs.
Each PWM output has an individual 4-bit intensity con-
trol (Table 14). When all outputs are to be used with the
same PWM setting, the outputs can be controlled
together instead using the global intensity control
(Table 13). Table 10 shows how to set up the MAX7314
to suit a particular application.
PWM Timing
The PWM control uses a 240-step PWM period, divided
into 15 master intensity timeslots. Each master intensity
timeslot is divided further into 16 PWM cycles (Figure 12).
The master intensity operates as a gate, allowing the indi-
vidual output settings to be enabled from 1 to 15 timeslots
per PWM period (Figures 13, 14, 15) (Table 13).
MAX7314
18-Port GPIO with LED Intensity Control,
Interrupt, and Hot-Insertion Protection
______________________________________________________________________________________ 15
Table 5. Ports Configuration Registers
REGISTER DATA
REGISTER R/WADDRESS
CODE
(hex) D7 D6 D5 D4 D3 D2 D1 D0
Ports configuration P7–P0
(1 = input, 0 = output) 0
Read back ports configuration P7–P0 1
0x06 OP7 OP6 OP5 OP4 OP3 OP2 OP1 OP0
Ports configuration P15–P8
(1 = input, 0 = output) 0
Read back ports configuration P15–P8 1
0x07 OP15 OP14 OP13 OP12 OP11 OP10 OP9 OP8
Table 6. Input Ports Registers
REGISTER DATA
REGISTER R/WADDRESS
CODE
(hex) D7 D6 D5 D4 D3 D2 D1 D0
Read input ports P7–P0 1 0x00 IP7 IP6 IP5 IP4 IP3 IP2 IP1 IP0
Read input ports P15–P8 1 0x01 IP15 IP14 IP13 IP12 IP11 IP10 IP9 IP8
Table 7. Blink Logic
BLINK ENABLE
FLAG E
BLINK FLIP
FLAG B
BLINK INPUT
PIN
BLINK FLIP FLAG
EXOR
BLINK INPUT PIN
BLINK FUNCTION OUTPUT REGISTERS USED
0 X X X Disabled Blink phase 0 registers
0 0 0 Blink phase 0 registers
0 1 1 Blink phase 1 registers
1 0 1 Blink phase 1 registers
1
11 0
Enabled
Blink phase 0 registers
MAX7314
Each output’s individual 4-bit intensity control only
operates during the number of timeslots gated by the
master intensity. The individual controls provide 16
intensity settings from 1/16 through 16/16 (Table 14).
Figures 16, 17, and 18 show examples of individual
intensity control settings. The highest value an individ-
ual or global setting can be set to is 16/16. This setting
forces the output to ignore the master control, and fol-
low the logic level set by the appropriate blink phase
register bit. The output becomes a glitch-free static out-
put with no PWM.
Using PWM Intensity Controls with Blink Disabled
When blink is disabled (Table 7), the blink phase 0 reg-
isters specify each output’s logic level during the PWM
on-time (Table 8). The effect of setting an output’s blink
phase 0 register bit to zero or 1 is shown in Table 11.
With its output bit set to zero, an LED can be controlled
with 16 intensity settings from 1/16th duty through fully
on, but cannot be turned fully off using the PWM inten-
sity control. With its output bit set to 1, an LED can be
controlled with 16 intensity settings from fully off
through 15/16th duty.
Using PWM Intensity Controls with Blink Enabled
When blink is enabled (Table 7), the blink phase 0 regis-
ters and blink phase 1 registers specify each output’s
logic level during the PWM on-time during the respective
blink phases (Tables 8 and 9). The effect of setting an
output’s blink phase x register bit to zero or 1 is shown in
Table 12. LEDs can be flipped between either directly on
and off, or between a variety of high/low PWM intensities.
Global/O16 Intensity Control
The 4 bits used for output O16’s PWM individual inten-
sity setting also double as the global intensity control
(Table 13). Global intensity simplifies the PWM settings
when the application requires them all to be the same,
such as for backlight applications, by replacing the 17
individual settings with 1 setting. Global intensity is
enabled with the global intensity flag G in the configura-
tion register (Table 4). When global PWM control is
used, the 4 bits of master intensity and 4 bits of global
intensity effectively combine to provide an 8-bit, 240-
step intensity control applying to all outputs.
It is not possible to apply global PWM control to a sub-
set of the ports, and use the others as logic outputs. To
mix static logic outputs and PWM outputs, individual
PWM control must be selected (Table 10).
18-Port GPIO with LED Intensity Control,
Interrupt, and Hot-Insertion Protection
16 ______________________________________________________________________________________
Table 8. Blink Phase 0 Registers
REGISTER DATA
REGISTER R/WADDRESS
CODE
(hex) D7 D6 D5 D4 D3 D2 D1 D0
Write outputs P7–P0 phase 0 0
Read back outputs P7–P0 phase 0 1 0x02 OP7 OP6 OP5 OP4 OP3 OP2 OP1 OP0
Write outputs P15–P8 phase 0 0
Read back outputs P15–P8 phase 0 1 0x03 OP15 OP14 OP13 OP12 OP11 OP10 OP9 OP8
Table 9. Blink Phase 1 Registers
REGISTER DATA
REGISTER R/WADDRESS
CODE
(hex) D7 D6 D5 D4 D3 D2 D1 D0
Write outputs P7–P0 phase 1 0
Read back outputs P7–P0 phase 1 1 0x0A OP7 OP6 OP5 OP4 OP3 OP2 OP1 OP0
Write outputs P15–P8 phase 1 0
Read back outputs P15–P8 phase 1 1 0x0B OP15 OP14 OP13 OP12 OP11 OP10 OP9 OP8
MAX7314
18-Port GPIO with LED Intensity Control,
Interrupt, and Hot-Insertion Protection
______________________________________________________________________________________ 17
Table 10. PWM Application Scenarios
APPLICATION RECOMMENDED CONFIGURATION
All outputs static without PWM
Set the master, O16 intensity register 0x0E to any value 0x00 to 0xOF.
The global intensity G bit in the configuration register is don't care.
The output intensity registers 0x10 through 0x17 are don't care.
A mix of static and PWM outputs, with PWM
outputs using different PWM settings
Set the master and global intensity register 0x0E to any value from 0x10 to 0xFF.
Clear global intensity G bit to zero in the configuration register to disable global
intensity control.
For the static outputs, set the output intensity value to 0xF.
For the PWM outputs, set the output intensity value in the 0x0 to 0xE range.
A mix of static and PWM outputs, with PWM
outputs all using the same PWM setting
As above. Global intensity control cannot be used with a mix of static and PWM
outputs, so write the individual intensity registers with the same PWM value.
All outputs PWM using the same PWM
setting
Set the master, O16 intensity register 0x0E to any value from 0x10 to 0xFF.
Set global intensity G bit to 1 in the configuration register to enable global intensity
control.
The master, O16 intensity register 0x0E is the only intensity register used.
The output intensity registers 0x10 through 0x17 are don't care.
Figure 12. PWM Timing
ONE PWM PERIOD IS 240 CYCLES OF THE 32kHz PWM
OSCILLATOR. A PWM PERIOD CONTAINS 15 MASTER
INTENSITY TIMESLOTS
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 14 15 1 2
EACH MASTER INTENSITY
TIMESLOT CONTAINS 16
PWM CYCLES
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 15 16 1 2
Figure 13. Master Set to 1/15
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 14 15 2 1
.
Figure 15. Master Set to 15/15
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 14 15 2 1
.
.
Figure 14. Master Set to 14/15
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 14 15 2 1
.
.
MAX7314
18-Port GPIO with LED Intensity Control,
Interrupt, and Hot-Insertion Protection
18 ______________________________________________________________________________________
Figure 17. Individual (or Global) Set to 15/16
MASTER INTENSITY TIMESLOT
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
NEXT MASTER INTENSITY TIMESLOT
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
Figure 16. Individual (or Global) Set to 1/16
MASTER INTENSITY TIMESLOT
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
NEXT MASTER INTENSITY TIMESLOT
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
Figure 18. Individual (or Global) Set to 16/16
MASTER INTENSITY TIMESLOT CONTROL IS IGNORED
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
Table 11. PWM Intensity Settings (Blink Disabled)
PWM DUTY CYCLE
OUTPUT BLINK PHASE 0
REGISTER BIT = 0
PWM DUTY CYCLE
OUTPUT BLINK PHASE 0
REGISTER = 1
OUTPUT
(OR
GLOBAL)
INTENSITY
SETTING LOW TIME HIGH TIME
LED BEHAVIOR WHEN
OUTPUT BLINK PHASE 0
REGISTER BIT = 0
(LED IS ON WHEN
OUTPUT IS LOW) LOW TIME HIGH TIME
LED BEHAVIOR WHEN
OUTPUT BLINK PHASE 0
REGISTER BIT = 1
(LED IS ON WHEN
OUTPUT IS LOW)
0x0 1/16 15/16 Lowest PWM intensity 15/16 1/16 Highest PWM intensity
0x1 2/16 14/16 14/16 2/16
0x2 3/16 13/16 13/16 3/16
0x3 4/16 12/16 12/16 4/16
0x4 5/16 11/16 11/16 5/16
0x5 6/16 10/16 10/16 6/16
0x6 7/16 9/16 9/16 7/16
0x7 8/16 8/16 8/16 8/16
0x8 9/16 7/16 7/16 9/16
0x9 10/16 6/16 6/16 10/16
0xA 11/16 5/16 5/16 11/16
0xB 12/16 4/16 4/16 12/16
0xC 13/16 3/16 3/16 13/16
0xD 14/16 2/16
Increasing PWM intensity
2/16 14/16
Increasing PWM intensity
0xE 15/16 1/16 Highest PWM intensity 1/16 15/16 Lowest PWM intensity
0xF Static low Static low Full intensity, no PWM
(LED on continuously)
Static high
impedance
Static high
impedance LED off continuously
Applications Information
Hot Insertion
I/O ports P0–P15, interrupt output INT/O16, RST input,
BLINK input, and serial interface SDA, SCL, AD0 remain
high impedance with up to 6V asserted on them when
the MAX7314 is powered down (V+ = 0V). The MAX7314
can therefore be used in hot-swap applications.
Output Level Translation
The open-drain output architecture allows the ports to
level translate the outputs to higher or lower voltages
than the MAX7314 supply. An external pullup resistor
can be used on any output to convert the high-imped-
ance logic-high condition to a positive voltage level.
The resistor can be connected to any voltage up to
5.5V. For interfacing CMOS inputs, a pullup resistor
value of 220kΩis a good starting point. Use a lower
resistance to improve noise immunity, in applications
where power consumption is less critical, or where a
faster rise time is needed for a given capacitive load.
Driving LED Loads
When driving LEDs, a resistor in series with the LED
must be used to limit the LED current to no more than
50mA. Choose the resistor value according to the fol-
lowing formula:
RLED = (VSUPPLY - VLED - VOL) / ILED
where:
RLED is the resistance of the resistor in series with the
LED (Ω).
VSUPPLY is the supply voltage used to drive the LED (V).
VLED is the forward voltage of the LED (V).
VOL is the output low voltage of the MAX7314 when
sinking ILED (V).
ILED is the desired operating current of the LED (A).
For example, to operate a 2.2V red LED at 14mA from a
5V supply, RLED = (5 - 2.2 - 0.25) / 0.014 = 182Ω.
MAX7314
18-Port GPIO with LED Intensity Control,
Interrupt, and Hot-Insertion Protection
______________________________________________________________________________________ 19
Table 12. PWM Intensity Settings (Blink Enabled)
EXAMPLES OF LED BLINK BEHAVIOR
(LED IS ON WHEN OUTPUT IS LOW)
PWM DUTY CYCLE
OUTPUT BLINK
PHASE X
REGISTER BIT = 0
PWM DUTY CYCLE
OUTPUT BLINK
PHASE X
REGISTER = 1
OUTPUT
(OR
GLOBAL)
INTENSITY
SETTING LOW
TIME
HIGH
TIME
LOW
TIME
HIGH
TIME
BLINK PHASE 0
REGISTER BIT = 0
BLINK PHASE 1
REGISTER BIT = 1
BLINK PHASE 0
REGISTER BIT = 1
BLINK PHASE 1
REGISTER BIT = 0
0x0 1/16 15/16 15/16 1/16
0x1 2/16 14/16 14/16 2/16
0x2 3/16 13/16 13/16 3/16
0x3 4/16 12/16 12/16 4/16
0x4 5/16 11/16 11/16 5/16
0x5 6/16 10/16 10/16 6/16
0x6 7/16 9/16 9/16 7/16
P hase 0: LE D on at l ow i ntensi ty
P hase 1: LE D on at hi g h i ntensi ty
P hase 0: LE D on at hi g h i ntensi ty
P hase 1: LE D on at l ow i ntensi ty
0x7 8/16 8/16 8/16 8/16 Output is half intensity during both blink phases
0x8 9/16 7/16 7/16 9/16
0x9 10/16 6/16 6/16 10/16
0xA 11/16 5/16 5/16 11/16
0xB 12/16 4/16 4/16 12/16
0xC 13/16 3/16 3/16 13/16
0xD 14/16 2/16 2/16 14/16
0xE 15/16 1/16 1/16 15/16
P hase 0: LE D on at hi g h i ntensi ty
P hase 1: LE D on at l ow i ntensi ty
P hase 0: LE D on at l ow i ntensi ty
P hase 1: LE D on at hi g h i ntensi ty
0xF Static low Static low Static high
impedance
Static high
impedance
Phase 0: LED on continuously
Phase 1: LED off continuously
Phase 0: LED off continuously
Phase 1: LED on continuously
MAX7314
18-Port GPIO with LED Intensity Control,
Interrupt, and Hot-Insertion Protection
20 ______________________________________________________________________________________
Table 13. Master, O16 Intensity Register
REGISTER DATA
REGISTER
ADDRESS
CODE
(hex) D7 D6 D5 D4 D3 D2 D1 D0
MSB LSB MSB LSB
MASTER AND GLOBAL INTENSITY
R/W
MASTER INTENSITY O16 INTENSITY
Write master and global intensity 0
Read back master and global intensity 1 M3 M2 M1 M0 G3 G2 G1 G0
Master intensity duty cycle is 0/15 (off);
internal oscillator is disabled;
all outputs will be static with no PWM
— 0000————
Master intensity duty cycle is 1/15 — 0001————
Master intensity duty cycle is 2/15 — 0010————
Master intensity duty cycle is 3/15 — 0011————
— — ————————
Master intensity duty cycle is 13/15 — 1101————
Master intensity duty cycle is 14/15 — 1110————
Master intensity duty cycle is 15/15 (full) — 1111————
O16 intensity duty cycle is 1/16 — — — — — 0 0 0 0
O16 intensity duty cycle is 2/16 — — — — — 0 0 0 1
O16 intensity duty cycle is 3/16 — — — — — 0 0 1 0
— — ————————
O16 intensity duty cycle is 14/16 — — — — — 1 1 0 1
O16 intensity duty cycle is 15/16 — — — — — 1 1 1 0
O16 intensity duty cycle is 16/16
(static output, no PWM) —
0X0E
———— 1 1 1 1
MAX7314
18-Port GPIO with LED Intensity Control,
Interrupt, and Hot-Insertion Protection
______________________________________________________________________________________________________ 21
Table 14. Output Intensity Registers
REGISTER DATA
REGISTER
ADDRESS
CODE
(hex) D7 D6 D5 D4 D3 D2 D1 D0
MSB LSB MSB
LSB
OUTPUTS P1, P0 INTENSITY
R/W
OUTPUT P1 INTENSITY OUTPUT P0 INTENSITY
Write output P1, P0 intensity
0
Read back output P1, P0 intensity
1P1I3 P1I2 P1I1 P1I0 P0I3 P0I2 P0I1
Output P1 intensity duty cycle is 1/16
—
0000————
Output P1 intensity duty cycle is 2/16
—
0001————
Output P1 intensity duty cycle is 3/16
—
0010————
—
—
————————
Output P1 intensity duty cycle is 14/16
—
1101————
Output P1 intensity duty cycle is 15/16
—
1110————
Output P1 intensity duty cycle is 16/16
(static logic level, no PWM)
—
1111————
Output P0 intensity duty cycle is 1/16
—
———— 0 0 0 0
Output P0 intensity duty cycle is 2/16
—
———— 0 0 0 1
Output P0 intensity duty cycle is 3/16
—
———— 0 0 1 0
—
—
————————
Output P0 intensity duty cycle is 14/16
—
———— 1 1 0 1
Output P0 intensity duty cycle is 15/16
—
———— 1 1 1 0
Output P0 intensity duty cycle is 16/16
(static logic level, no PWM)
—
0X10
———— 1 1 1 1
MSB LSB MSB
LSB
OUTPUTS P3, P2 INTENSITY OUTPUT P3 INTENSITY OUTPUT P2 INTENSITY
Write output P3, P2 intensity
0
Read back output P3, P2 intensity
1
0x11
P3I3 P3I2 P3I1 P3I0 P2I3 P2I2 P2I1
MSB LSB MSB
LSB
OUTPUTS P5, P4 INTENSITY OUTPUT P5 INTENSITY OUTPUT P4 INTENSITY
Write output P5, P4 intensity
0
Read back output P5, P4 intensity
1
0x12
P5I3 P5I2 P5I1 P5I0 P4I3 P4I2 P4I1
MSB LSB MSB
LSB
OUTPUTS P7, P6 INTENSITY OUTPUT P7 INTENSITY OUTPUT P6 INTENSITY
Write output P7, P6 intensity
0
Read back output P7, P6 intensity
1
0x13
P7I3 P7I2 P7I1 P7I0 P6I3 P6I2 P6I1
MAX7314
Driving Load Currents Higher than 50mA
The MAX7314 can be used to drive loads drawing more
than 50mA, like relays and high-current white LEDs, by
paralleling outputs. Use at least one output per 50mA of
load current; for example, a 5V 330mW relay draws
66mA and needs two paralleled outputs to drive it.
Ensure that the paralleled outputs chosen are controlled
by the same blink phase register, i.e., select outputs
from the P0 through P7 range, or the P8 through P15
range. This way, the paralleled outputs are turned on
and off together. Do not use output O16 as part of a
load-sharing design. O16 cannot be switched at the
same time as any of the other outputs because it is con-
trolled by a different register.
The MAX7314 must be protected from the negative
voltage transient generated when switching off induc-
tive loads, such as relays, by connecting a reverse-
biased diode across the inductive load (Figure 19). The
peak current through the diode is the inductive load’s
operating current.
Power-Supply Considerations
The MAX7314 operates with a power-supply voltage of
2V to 3.6V. Bypass the power supply to GND with at
least 0.047µF as close to the device as possible. For
the QFN version, connect the underside exposed pad
to GND.
18-Port GPIO with LED Intensity Control,
Interrupt, and Hot-Insertion Protection
22 ______________________________________________________________________________________
Table 14. Output Intensity Registers (continued)
REGISTER DATA
REGISTER
ADDRESS
CODE
(hex) D7 D6 D5 D4 D3 D2 D1 D0
MSB LSB MSB
LSB
OUTPUTS P9, P8 INTENSITY
R/W
OUTPUT P9 INTENSITY OUTPUT P8 INTENSITY
Write output P9, P8 intensity
0
Read back output P9, P8 intensity
1
0x14
P9I3 P9I2 P9I1 P9I0 P8I3 P8I2 P8I1
P8I0
MSB LSB MSB
LSB
OUTPUTS P11, P10 INTENSITY OUTPUT P11 INTENSITY OUTPUT P10 INTENSITY
Write output P11, P10 intensity
0
Read back output P11, P10 intensity
1
0x15
P11I3 P11I2 P11I1 P11I0 P10I3 P10I2 P10I1
P10I0
MSB LSB MSB
LSB
OUTPUTS P13, P12 INTENSITY OUTPUT P13 INTENSITY OUTPUT P12 INTENSITY
Write output P13, P12 intensity
0
Read back output P13, P12 intensity
1
0x16
P13I3 P13I2 P13I1 P13I0 P12I3 P12I2 P12I1
P12I0
MSB LSB MSB
LSB
OUTPUTS P15, P14 INTENSITY OUTPUT P15 INTENSITY OUTPUT P14 INTENSITY
Write output P15, P14 intensity
0
Read back output P15, P14 intensity
1
0x17
P15I3 P15I2 P15I1 P15I0 P14I3 P14I2 P14I1
P14I0
OUTPUT O16 INTENSITY See master, O16 intensity register (Table 13).
MAX7314
18-Port GPIO with LED Intensity Control,
Interrupt, and Hot-Insertion Protection
______________________________________________________________________________________ 23
Figure 19. Diode-Protected Switching Inductive Load
MAX7314
P8
P10
P0
P1
P2
P3
P4
P5
P6
P7
V+
2V TO 3.6V
μC
SDA SDA
AD0
P11
P12
P13
P14
P15
SCL
SCL
BLINK
I/O
RST
I/O
P9
GND
0.047μF
INT INT/O16
BAS16
5V
24
23
22
21
20
19
18
17
1
2
3
4
5
6
7
8
V+
SDA
SCL
BLINKP0
AD0
RST
TOP VIEW
P15
P14
P13
P12P4
P3
P2
P1
16
15
14
13
9
10
11
12
P11
P10
P9
P8GND
P7
P6
P5
QSOP
MAX7314AEG
INT/O16
Chip Information
TRANSISTOR COUNT: 25,991
PROCESS: BiCMOS
TOP VIEW
THIN QFN
MAX7314ATG
19
20
21
22
12 3456
18 17 16 15 14 13
23
24
12
11
10
9
8
7
SCL
V+
SDA
INT/O16
AD0
P0
P1
P2
P3
P4
P5
BLINK
P15
P13
P12
P11
RST
P10
P8
P9
GND
P6
P7
P14
Pin Configurations
MAX7314
18-Port GPIO with LED Intensity Control,
Interrupt, and Hot-Insertion Protection
24 ______________________________________________________________________________________
QSOP EPS
Package Information
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information,
go to www.maxim-ic.com/packages.)
MAX7314
18-Port GPIO with LED Intensity Control,
Interrupt, and Hot-Insertion Protection
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are
implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 ____________________ 25
© 2005 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products, Inc.
24L QFN THIN.EPS
Package Information (continued)
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information,
go to www.maxim-ic.com/packages.)