1 Features
• Operating power-supply voltage range of 1.08 V to
3.6 V
• Low standby current consumption of 1 μA typical
at 1.8 V
• 1-MHz fast mode plus I2C bus
• Hardware address pin allows two devices on the
same I2C, SMBus bus
• Active-low reset input (RESET )
• Open-drain active-low interrupt output (INT )
• Input or output configuration register
• Polarity inversion register
• Configurable I/O drive strength register
• Pull-up and pull-down resistor configuration
register
• Internal power-on reset
• Noise filter on SCL or SDA inputs
• 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
– 4000-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
• Gaming consoles
• Products with GPIO-limited processors

3 Description
The TCAL9538 device provides general purpose
parallel input/output (I/O) expansion for the two-line
bidirectional I2C bus (or SMBus) protocol and is
designed for 1.08-V to 3.6-V VCC operation.
The device supports 100-kHz (Standard-mode), 400-
kHz (Fast-mode), and 1-MHz (fast-mode-plus) I2C
clock frequencies. I/O expanders such as the
TCAL9538 provide a simple solution when additional
I/Os are needed for switches, sensors, push-buttons,
LEDs, fans, and so on.
The TCAL9538 has Agile I/O ports which include
additional features designed to enhance the I/O
performance in terms of speed, power consumption
and EMI. The additional features are: programmable
output drive strength, programmable pull-up and pulldown
resistors, latchable inputs, maskable interrupt,
interrupt status register, and programmable opendrain
or push-pull outputs.