Two-wire remote I/O expansion chip CH423


The CH423 is a universal remote I/O expansion chip with a two-wire serial interface. CH423 provides 8 bidirectional input and output pins and 16 general-purpose output pins to support input level change interrupt. CH423 built-in current drive circuit can statically drive 24 LED tubes or dynamically drive 128 LEDs (equivalent to 16 digital) Tube); CH423 exchanges data with a single-chip microcomputer through a 2-wire serial interface.


  • 8 general-purpose input and output pins GPIO and 16 general-purpose output pin GPOs are remotely extended through a two-wire serial interface.
  • Built-in current drive stage, continuous drive current is not less than 15mA, OC pin output 1/16 pulse sink current is not less than 120mA.
  • The static display drive mode supports 24 LEDs or 3 LEDs.
  • The time-sharing dynamic scanning display drive mode supports 128 LEDs or 16-bit common cathode digital tubes, and supports brightness control.
  • The bidirectional I/O pin has an interrupt function when the input level changes in the input mode, and the interrupt output is active low.
  • The 16 general-purpose output pins can be selected for push-pull output or open-drain output.
  • Supports 3V ~ 5V power supply voltage, supports low-power sleep, can be awakened by input level changes.
  • High-speed 2-wire serial interface with clock speeds from 0 to 1MHz, compatible with two-wire I2C bus, saving pins.
  • Available in SOP28 and SOP28 lead-free packages, compatible with RoHS.

relation files

file name file content
CH422DS1.PDF CH422 datasheet. Remote I/O expander chip of two-wire serial interface, used for display of 4 digital tubes and I/O expansion application. The input is a two-wire interface compatible with I2C, and the output is an 8-bit bidirectional I/O port and 4-bit large-current output port.