1 Features
• 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
• Compatible with most microcontrollers
• 400-kHz Fast I2C Bus
• Address by three hardware address pins for use of
up to eight devices
• 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 Description
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 PCA9535 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
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 PCA9535 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 PCA9535 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.