PCA9545A

www.DataSheet4U.com PCA9545A 4-channel I2C switch with interrupt logic and reset Rev. 03 — 3 March 2005 Product data sheet 1. General description The PCA9545A is a quad bi-directional translating switch controlled via the I2C-bus. The SCL/SDA upstream pair fans out to four downstream pairs, or channels. Any individual SCx/SDx channel or combination of channels can be selected, determined by the contents of the programmable control register. Four interrupt inputs, INT0 to INT3, one for each of the downstream pairs, are provided. One interrupt output, INT, acts as an AND of the four interrupt inputs. An active LOW reset input allows the PCA9545A to recover from a situation where one of the downstream I2C-buses is stuck in a LOW state. Pulling the RESET pin LOW resets the I2C-bus state machine and causes all the channels to be deselected as does the internal Power-on reset function. The pass gates of the switches are constructed such that the VDD pin can be used to limit the maximum high voltage which will be passed by the PCA9545A. This allows the use of different bus voltages on each pair, so that 1.8 V or 2.5 V or 3.3 V parts can communicate with 5 V parts without any additional protection. External pull-up resistors pull the bus up to the desired voltage level for each channel. All I/O pins are 5 V tolerant. 2. Features s s s s s s s s s s s s s s s s s 1-of-4 bi-directional translating switches I2C-bus interface logic; compatible with SMBus standards 4 active LOW interru...