TCA6424A

The TCA6424A is a 24-bit I²C-bus and SMBus expandable GPIO port expander designed for low-power applications. It features four independent 8-bit ports, each configurable as input or output with individual pull-up resistor control, enabling flexible interface expansion in space-constrained designs. The device operates over a wide supply voltage range of 1.65 V to 5.5 V, making it compatible with various system voltages including 1.8 V, 3.3 V, and 5 V logic levels. Each port includes an open-drain output driver capable of sinking up to 24 mA per pin, allowing direct drive of LEDs, relays, or other low-current peripherals without external drivers. The integrated configuration registers support programmable input filtering to reduce noise on external signals, while the interrupt output (INT) can be used to signal status changes on any configured input pin, minimizing host processor polling overhead. Communication with the TCA6424A is achieved via a standard I²C/SMBus interface operating at speeds up to 400 kHz, supporting multi-master configurations and address selection via two hardware pins for up to 16 unique devices on the same bus. This feature simplifies system design when multiple GPIO expanders are required across different subsystems. The TCA6424A also includes a power-on reset (POR) circuit that ensures a defined state upon startup, along with a watchdog timer function for enhanced reliability in embedded systems. Its low quiescent current—typically 1 μA in standby mode—makes it ideal for battery-powered or energy-efficient applications such as portable electronics, IoT devices, and industrial sensors. This IC supports both active-low and active-high interrupt signaling, offering flexibility in system integration. Additionally, its robust ESD protection (±4 kV HBM) enhances durability in harsh environments, while the 28-pin QFN package provides a compact footprint suitable for high-density PCB layouts.