TCA9548A-Q1

The TCA9548A-Q1 device has eight bidirectional translating switches that can be controlled through the I 2C bus. The SCL/SDA upstream pair fans out to eight downstream pairs, or channels. Any individual SCn/SDn channel or combination of channels can be selected, determined by the contents of the programmable control register. These downstream channels can be used to resolve I 2C target address conflicts. For example, if eight identical digital temperature sensors are needed in the application, one sensor can be connected at each channel: 0-7.

The system controller can reset the TCA9548A-Q1 in the event of a time-out or other improper operation by asserting a low in the RESET input. Similarly, the power-on reset deselects all channels and initializes the I 2C/SMBus state machine. Asserting RESET causes the same reset and initialization to occur without powering down the part. This allows recovery should one of the downstream I 2C buses get stuck in a low state.

The pass gates of the switches are constructed so that the VCC pin can be used to limit the maximum high voltage, which is passed by the TCA9548A-Q1. Limiting the maximum high voltage allows the use of different bus voltages on each pair, so that 1.8 V, 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.