PCA9538
REMOTE 8-BIT I2C AND SMBus LOW-POWER I/O EXPANDER
WITH INTERRUPT OUTPUT, RESET, AND CONFIGURATION REGISTERS
www.ti.com
SCPS126D–SEPTEMBER 2006–REVISED MARCH 2007
FEATURES
•
Low Standby Current Consumption of
1 µA Max
•
Power-Up With All Channels Configured as
Inputs
•
•
•
•
I2C to Parallel Port Expander
Open-Drain Active-Low Interrupt Output
Active-Low Reset Input
•
•
•
No Glitch on Power Up
Noise Filter on SCL/SDA Inputs
Latched Outputs With High-Current Drive
Maximum Capability for Directly Driving LEDs
Operating Power-Supply Voltage Range of
2.3 V to 5.5 V
•
•
Latch-Up Performance Exceeds 100 mA Per
JESD 78, Class II
•
•
•
5-V Tolerant I/O Ports
400-kHz Fast I2C Bus
ESD Protection Exceeds JESD 22
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2000-V Human-Body Model (A114-A)
200-V Machine Model (A115-A)
Two Hardware Address Pins Allow up to Four
Devices on the I2C/SMBus
•
•
Input/Output Configuration Register
Polarity Inversion Register
1000-V Charged-Device Model (C101)
RGV PACKAGE
(TOP VIEW)
DB, DBQ, DGV, DW, OR PW PACKAGE
(TOP VIEW)
RGT PACKAGE
(TOP VIEW)
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
A0
A1
V
CC
16 15 14 13
16 15 14 13
1
12
RESET
P0
SCL
INT
P7
SDA
SCL
INT
P7
P6
P5
1
12
RESET
SCL
INT
P7
RESET
P0
2
3
4
11
10
9
2
3
11
10
P0
P1
P2
P1
P1
P2
P3
4
9
P6
P2
P6
5
6
7
8
5
6
7
8
GND
P4
DESCRIPTION/ORDERING INFORMATION
This 8-bit I/O expander for the two-line bidirectional bus (I2C) is designed for 2.3-V to 5.5-V VCC operation. It
provides general-purpose remote I/O expansion for most microcontroller families via the I2C interface [serial
clock (SCL), serial data (SDA)].
The PCA9538 consists of one 8-bit Configuration (input or output selection), Input Port, Output Port, and Polarity
Inversion (active high or active low) registers. At power on, the I/Os are configured as inputs. However, the
system master can enable the I/Os as either inputs or outputs by writing to the I/O configuration bits. The data
for each input or output is kept in the corresponding Input Port or Output Port register. The polarity of the Input
Port register can be inverted with the Polarity Inversion register. All registers can be read by the system master.
The system master can reset the PCA9538 in the event of a timeout or other improper operation by asserting a
low in the RESET input. The power-on reset puts the registers in their default state and initializes the I2C/SMBus
state machine. The RESET pin causes the same reset/initialization to occur without powering down the part.
The PCA9538 open-drain interrupt (INT) output is activated when any input state differs from its corresponding
Input Port register state and is used to indicate to the system master that an input state has changed.
INT can be connected to the interrupt input of a microcontroller. By sending an interrupt signal on this line, the
remote I/O can inform the microcontroller if there is incoming data on its ports without having to communicate via
the I2C bus. Thus, the PCA9538 can remain a simple slave device.
The device outputs (latched) have high-current drive capability for directly driving LEDs. It has low current
consumption.
Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of Texas
Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
PRODUCTION DATA information is current as of publication date.
Copyright © 2006–2007, Texas Instruments Incorporated
Products conform to specifications per the terms of the Texas
Instruments standard warranty. Production processing does not
necessarily include testing of all parameters.