NXP Semiconductors PCA96xx 2-wire Bus Switch & Output Port are monolithic CMOS integrated circuits for 2-wire bus interfaces, including I2C-bus, SMBus, PMBus, and other systems based on similar principles. The NXP Semiconductors PCA9646 Buffered 4-channel 2-wire Bus Switch has four outputs which may be independently enabled in any combination as determined by the contents of the programmable control register. Each I/O is impedance isolated from all others, thus allowing a total of five branches of 2-wire bus with the maximum specified load. The PCA9646 has excellent application to 2-wire bus address expansion and increasing of maximum load capacitance, such as in very large LED displays.
The NXP Semiconductors PCA9621 8-bit 2-wire Bus Output Port has a 65mA sink capability, making it also 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. The 2-wire bus interface also has 30mA Fast-mode Plus (Fm+) capability, and consequently can be run in excess of 1MHz or up to 4000pF capacitance. As such, the PCA9621 can be connected to other 2-wire devices across long cable connections.