Embedded Interface – PCF8574 and PCF8574A I/O Expender


  • Two wire i2c Bus Interface
  • 8-Bit Parallel Bus Ex-panders
  • Operating Voltage VCC -2.5v to 6v
  • Up-to 8 Addressed by three hardware-address pins
  • Low standby current consumption 10mA maximum 
  • LED Driving (Latched output with high-current drive capability)

Typical Applications

  • Fan Control
  •  LED Driver
  • Cost effective method to monitor and several peripheral signals
  • Temperature Sensor Monitoring
  • 8-Bit Bidirectional  expansion

Block Diagram


Functional Description


Multiple PCF8574 and PCF8574A

Bi-Directional I/O Expander

High Current-Drive Load


What is the difference between PCF8574 and PCF8574A ?

   Main difference between the PCF8574 and PCF8574A is the i2c address

  • PCF8574 Address range (0x20 to 0x27 – up-to 8 device)
  • PCF8574A Address range (0x38 to 0x3F – up-to 8 device) 

 What is the difference between Ti-PCF8574 and Philips PCF8574?

  • Package 20 Pin TVSOP (23% smaller than 20 pin TSSOP)
  • Package 20 Pin QFN Package (62% smaller than 20-pin TSSOP)

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