PCA9555
www.ti.com ......................................................................................................................................................... SCPS131E–AUGUST 2005–REVISED MAY 2008
REMOTE 16-BIT I2C AND SMBus I/O EXPANDER
WITH INTERRUPT OUTPUT AND CONFIGURATION REGISTERS
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FEATURES
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Low Standby-Current Consumption of
1 µA Max
I2C to Parallel Port Expander
Open-Drain Active-Low Interrupt Output
5-V Tolerant I/O Ports
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Polarity Inversion Register
Latched Outputs With High-Current Drive
Capability for Directly Driving LEDs
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•
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Latch-Up Performance Exceeds 100 mA Per
JESD 78, Class II
ESD Protection Exceeds JESD 22
Compatible With Most Microcontrollers
400-kHz Fast I2C Bus
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2000-V Human-Body Model (A114-A)
200-V Machine Model (A115-A)
Address by Three Hardware Address Pins for
Use of up to Eight Devices
1000-V Charged-Device Model (C101)
DB, DBQ, DGV, DW, OR PW PACKAGE
(TOP VIEW)
RGE PACKAGE
(TOP VIEW)
1
24
23
22
21
20
19
18
17
16
15
14
13
INT
A1
V
CC
2
SDA
SCL
A0
24 23 22 21 20 19
3
A2
1
2
3
4
5
6
18 A0
P00
P01
P02
P03
P04
P05
4
P00
P01
P02
P03
P04
P05
P06
P07
GND
17 P17
16 P16
15 P15
14 P14
5
P17
P16
P15
P14
P13
P12
P11
P10
6
7
8
P13
13
9
7
8 9 10 11 12
10
11
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DESCRIPTION/ORDERING INFORMATION
This 16-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 PCA9555 consists of two 8-bit Configuration (input or output selection), Input Port, Output Port, and Polarity
Inversion (active high or active low operation) registers. At power on, the I/Os are configured as inputs. 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 PCA9555 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 I2C/SMBus state machine.
The PCA9555 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 PCA9555 can remain a simple slave device.
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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 © 2005–2008, 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.