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The PCA9621 is a monolithic CMOS integrated circuit for general purpose output drive configurable from a 2-wire bus interface (including I²C-bus, SMBus, PMBus, and other systems based on similar principles). Output ports have a 65 mA sink capability, making them ideal for driving LEDs.
The state of the outputs is determined by a programmable 8-bit register which can be read and written via signals from the 2-wire bus (e.g., I²C-bus or similar).
The 2-wire bus interface also has 30 mA Fast-mode Plus (Fm+) capability, and consequently can be run in excess of 1 MHz or up to 4000 pF capacitance. As such, the PCA9621 can be connected to other 2-wire devices across long cable connections.
It can be mixed with other Fast-mode Plus slaves in systems driven by Fm+ buffers or by the PCA9646 (fully buffered 4-channel bus switch) to build large scale systems with high-speed or high-capacitance drive capability, for example large scale LED displays or controlled lighting.