描述 Description

The PCF8574/74A provides general-purpose remote I/O expansion via the two-wirebidirectional I2C?bus (serial clock (SCL), serial data (SDA)).
The devices consist of eight quasi-bidirectional ports, 100?kHz I2C?bus interface, threehardware address inputs and interrupt output operating between 2.5?V and 6?V. Thequasi-bidirectional port can be independently assigned as an input to monitor interruptstatus or keypads, or as an output to activate indicator devices such as LEDs. Systemmaster can read from the input port or write to the output port through a single register.
The low current consumption of 2.5?μA (typical, static) is great for mobile applications andthe latched output ports directly drive LEDs.
The PCF8574 and PCF8574A are identical, except for the different fixed portion of theslave address. The three hardware address pins allow eight of each device to be on thesame I2C?bus, so there can be up to 16 of these I/O expanders PCF8574/74A together onthe same I2C?bus, supporting up to 128 I/Os (for example, 128 LEDs).
The active LOW open-drain interrupt output (INT) can be connected to the interrupt logicof the microcontroller and is activated when any input state differs from its correspondinginput port register state. It is used to indicate to the microcontroller that an input state haschanged and the device needs to be interrogated without the microcontroller continuouslypolling the input register via the I2C?bus.
The internal Power-On Reset (POR) initializes the I/Os as inputs with a weak internalpull-up 100?μA current source.

特性 Features

I2C-bus to parallel port expander
100 kHz I2C?bus interface (Standard-mode I2C-bus)
Operating supply voltage 2.5 V to 6?V with non-overvoltage tolerant I/O held to VDD with 100?μA current source
8-bit remote I/O pins that default to inputs at power-up
Latched outputs directly drive LEDs
Total package sink capability of 80?mA
Active LOW open-drain interrupt output
Eight programmable slave addresses using three address pins
Low standby current (2.5?μA typical)
-40?°C to +85?°C operation
ESD protection exceeds 2000 V HBM per JESD22-A114 and 1000 V CDM per JESD22-C101
Latch-up testing is done to JEDEC standard JESD78 which exceeds 100?mA
Packages offered: DIP16, SO16, SSOP20

應用 Application

LED signs and displays
Servers
Key pads
Industrial control
Medical equipment
PLC
Cellular telephones
Mobile devices
Gaming machines
Instrumentation and test measurement