1.

General description

The PCF8574/74A provides general-purpose remote I/O expansion via the two-wire

hardware address inputs and interrupt output operating between 2.5 V and 6 V. The

quasi-bidirectional port can be independently assigned as an input to monitor interrupt

status or keypads, or as an output to activate indicator devices such as LEDs. System

master can read from the input port or write to the output port through a single register.

The low current consumption of 2.5

A (typical, static) is great for mobile applications and

the latched output ports directly drive LEDs.

The PCF8574 and PCF8574A are identical, except for the different fixed portion of the

slave address. The three hardware address pins allow eight of each device to be on the

The active LOW open-drain interrupt output (INT) can be connected to the interrupt logic

of the microcontroller and is activated when any input state differs from its corresponding

input port register state. It is used to indicate to the microcontroller that an input state has

changed and the device needs to be interrogated without the microcontroller continuously

The internal Power-On Reset (POR) initializes the I/Os as inputs with a weak internal

pull-up 100

A current source.

2.

Features and benefits

with 100

A current source

A typical)



40 C to +85 C operation

JESD22-C101

PCF8574; PCF8574A

Rev. 5 — 27 May 2013

Product data sheet