1 Features
1• Low Standby-Current Consumption of
3.5 μA Maximum
• I2C to Parallel Port Expander
• Open-Drain Active-Low Interrupt Output
• 5-V Tolerant I/O Ports
• Compatible With Most Microcontrollers
• 400-kHz Fast I2C Bus
• Configurable Slave Address with 3 Address Pins
• Polarity Inversion Register
• Latched Outputs With High-Current Drive
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)
– 1000-V Charged-Device Model (C101)

2 Applications
. Servers
. Routers (Telecom Switching Equipment)
. Personal Computers
. Personal Electronics
. Industrial Automation Equipment
. Products with GPIO-Limited Processors

3 Description
This 16-bit I/O expander for the two-line bidirectional
bus (I2C) is designed for 1.65-V to 5.5-V VCC
operation. It provides general-purpose remote I/O
expansion for most microcontroller families via the I2C
interface.
The TCA9555 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.