The PCA9646 is a monolithic CMOS integrated circuit for 2-wire bus buffering and switching in applications including I2C-bus, SMBus, PMBus, and other systems based on similar principles. Each of the four outputs 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 (e.g., 5 400 pF for Fm+ I2C-bus at 1 MHz, or 5 4 nF at lower frequencies) (Ref. 1). More than one PCA9646 may be used in series, providing a substantial fan-out capability. As per the PCA9525 and PCA9605 simple bus buffers, the PCA9646 includes a unidirectional buffer for the clock signal, and a bidirectional buffer for the data signal. The direction of the clock signal may also be set by the contents of the programmable control register. Clock stretching and timing must always be under control of the master device. The PCA9646 has excellent application to 2-wire bus address expansion and increasing of maximum load capacitance. Very large LED displays are a perfect example.
The PCA9646 is a monolithic CMOS integrated circuit that provides buffered 4‑channel 2‑wire bus switching for I²C‑bus, SMBus, PMBus and similar systems. Each channel can be independently enabled and isolated, allowing up to five bus branches with high capacitance loads.
The document includes a functional description, pin‑out tables, electrical characteristics, ordering information and handling guidelines, making it a complete reference for designers integrating the device into LED displays, power‑management or other high‑load bus applications.
| Supply voltage (operating) | 2.7 V – 5.5 V |
|---|---|
| Static sink capability per port | 30 mA |
| Maximum power dissipation | 300 mW |
The device operates from 2.7 V up to 5.5 V.
All four channels (SC0‑SC3 and SD0‑SD3) can be enabled independently.
Each port can sink up to 30 mA.
No, the part is non‑automotive qualified unless explicitly stated otherwise.