REMOTE 8-BIT I C AND SMBus I/O EXPANDER
WITH INTERRUPT OUTPUT AND CONFIGURATION REGISTERS
2
www.ti.com
SCPS127A – SEPTEMBER 2006 – REVISED FEBRUARY 2007
FEATURES
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I
2
C to Parallel Port Expander
Open-Drain Active-Low Interrupt Output
Operating Power-Supply Voltage Range of
2.3 V to 5.5 V
5-V Tolerant I/Os
400-kHz Fast I
2
C Bus
Three Hardware Address Pins Allow up to
Eight Devices on the I
2
C/SMBus
Input/Output Configuration Register
Polarity Inversion Register
Internal Power-On Reset
DB, DBQ, DGV, DW,
OR PW PACKAGE
(TOP VIEW)
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Power-Up With All Channels Configured as
Inputs
No Glitch on Power-Up
Latched Outputs With High-Current Drive
Maximum Capability for Directly Driving LEDs
Latch-Up Performance Exceeds 100 mA Per
JESD 78, Class II
ESD Protection Exceeds JESD 22
– 2000-V Human-Body Model (A114-A)
– 200-V Machine Model (A115-A)
– 1000-V Charged-Device Model (C101)
RGT PACKAGE
(TOP VIEW)
RGV PACKAGE
(TOP VIEW)
SDA
V
CC
GND
P3
DESCRIPTION/ORDERING INFORMATION
This 8-bit I/O expander for the two-line bidirectional bus (I
2
C) is designed for 2.3-V to 5.5-V V
CC
operation. It
provides general-purpose remote I/O expansion for most microcontroller families via the I
2
C interface [serial
clock (SCL), serial data (SDA)].
The PCA9554A consists of one 8-bit Configuration (input or output selection), Input, Output, and Polarity
Inversion (active high or active low) registers. At power-on, the I/Os are configured as inputs with a weak pull up
to V
CC
. 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 or Output 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 PCA9554A in the event of a timeout or other improper operation by utilizing
the power-on reset feature which puts the registers in their default state and initializes the I
2
C/SMBus state
machine.
The PCA9554A 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 I
2
C bus. Thus, the PCA9554A can remain a simple slave device.
The device's outputs (latched) have high-current drive capability for directly driving LEDs and 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.
UNLESS OTHERWISE NOTED this document contains
PRODUCTION DATA information current as of publication date.
Products conform to specifications per the terms of Texas
Instruments standard warranty. Production processing does not
necessarily include testing of all parameters.
P4
P5
8
9
Copyright © 2006–2007, Texas Instruments Incorporated
P3
GND
P4
P5
A0
A1
A2
P0
P1
P2
P3
GND
1
2
3
4
5
6
7
16
15
14
13
12
11
10
V
CC
SDA
SCL
INT
P7
P6
P5
P4
16 15 14 13
A2
1
P0
2
P1
3
P2
4
5
6
7
8
12
SCL
11
INT
10
P7
9
P6
A2
P0
P1
P2
4
16 15 14 13
1
12
SCL
2
11
INT
10
P7
3
9
P6
5 6 7
8
A1
A0
V
CC
SDA
A1
A0
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