CH423S

CH423 is a general-purpose remote I/O expander chip with a two-wire serial interface. It provides 8 bidirectional I/O pins and 16 general-purpose output pins, with support for input level change interrupts. The chip integrates an internal current drive circuit capable of statically driving up to 24 LEDs, or dynamically driving up to 128 LEDs (equivalent to 16-digit seven-segment displays) via multiplexed scanning. It communicates with MCUs and other devices through a two-wire serial interface.

Key features

• Remote expansion of 8 GPIO pins and 16 general-purpose output pins via two-wire serial interface.
• Built-in current driver stage with continuous sink/source current ≥15mA; open-drain output 1/16 duty cycle pulse sink current ≥120mA.
• Static display drive supports 24 LEDs or 3-digit common-anode 7-segment displays.
• Time-division multiplexed dynamic scan display drive supports 128 LEDs or 16-digit common-cathode 7-segment displays, with brightness control.
• Bidirectional I/O pins configured as inputs support interrupt generation on input level change; interrupt output is active-low.
• 16 general-purpose output pins selectable between push-pull and open-drain output modes.
• Supports 3V~5V supply voltage; low-power sleep mode with wake-up on input level change.
• High-speed two-wire serial interface with clock frequency 0 to 1MHz; I²C bus compatible, minimizing pin count.
• Available in QFN28, SOP28, and DIP28S lead-free packages, RoHS compliant.