Low-voltage 16-bit I²C-bus I/O Port

PCA9555A Block Diagram

PCA9555A Block Diagram

PCA9555A is an NXP I/O expanders that provide a simple solution when additional I/Os are needed while keeping interconnections to a minimum. It is a low-voltage 16-bit General Purpose Input/Output (GPIO) expander with interrupt and weak pull-up resistors for I²C-bus/SMBus applications. The wide VDD range of 1.65 V to 5.5 V allows the PCA9555A to interface with next-generation microprocessors and microcontrollers where supply levels are dropping down to conserve power, considering the device provide a flexible set of GPIOs.

The device outputs have 25 mA sink capabilities for directly driving LEDs while consuming low device current. All input/outputs pins have weak pull-up resistors connected to them to eliminate external components.

Why Used

  • 5 V tolerant I/Os
  • I²C-bus to parallel port expander
  • 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)

Where Used

  • Sensors
  • LEDs
  • ACPI Power Switches
  • Fan Control
  • Push Buttons

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