General description
The PCA9535A is a low-voltage 16-bit General Purpose Input/Output (GPIO) expander with interrupt and reset for I2C-bus/SMBus applications. NXP I/O expanders provide a simple solution when additional I/Os are needed while keeping interconnections to a minimum, for example, in ACPI power switches, sensors, push buttons, LEDs, fan control, etc.
In addition to providing a flexible set of GPIOs, the wide VDD range of 1.65 V to 5.5 V allows the PCA9535A to interface with next-generation microprocessors and microcontrollers where supply levels are dropping down to conserve power.
The PCA9535A contains the PCA9535 register set of four pairs of 8-bit Configuration, Input, Output, and Polarity Inversion registers.
The PCA9535A is a pin-to-pin replacement to the PCA9535 and other industry-standard devices. A more fully featured device, the PCAL9535A, is available with Agile I/O features. See the respective data sheet for more details.
The device outputs have 25 mA sink capabilities for directly driving LEDs while consuming low device current.
The power-on reset sets the registers to their default values and initializes the device state machine.
Three hardware pins (A0, A1, A2) select the fixed I2C-bus address and allow up to eight devices to share the same I2C-bus/SMBus.

Features and benefits
■ I2C-bus to parallel port expander
■ Pin and function compatible with PCA9535
■ Operating power supply voltage range of 1.65 V to 5.5 V
■ Low standby current consumption:
   ◆ 1.5 μA (typical at 5 V VDD)
   ◆ 1.0 μA (typical at 3.3 V VDD)
■ Schmitt-trigger action allows slow input transition and better switching noise immunity
   at the SCL and SDA inputs
   ◆ Vhys = 0.10 x VDD (typical)
■ 5 V tolerant I/Os
■ Open-drain active LOW interrupt output (INT)
■ 400 kHz Fast-mode I2C-bus
■ Internal power-on reset
■ Power-up with all channels configured as inputs
■ No glitch on power-up
■ Latched outputs with 25 mA drive maximum capability for directly driving LEDs
■ Latch-up performance exceeds 100 mA per JESD78, Class II
■ ESD protection exceeds JESD22
   ◆ 2000 V Human Body Model (A114-A)
   ◆ 1000 V Charged-Device Model (C101)
■ Packages offered: TSSOP24, HWQFN24