Dear Team:
We have two questions.
1. TCA9548 has eight output channels. Do these output channels can work on different voltage level as shown in below topology?
2. From BMC to M.2 module, there are two I2C switch cascade on the path. Does it cause any side effect?
Here are the answers to your questions:
1) Yes these switches support level translation. Your diagram is incorrect. I have attached the image of it with correct Vcc for TCA9548A, it should be 1.8V or the lowest voltage supported on all the busses.
2) There are some potential issues when using switches in series. Problems arise when you try to turn on more than one channel at a time. For example, if you turned all 8 channels on the TCA9548A, the master device will have a hard time pulling down the node from all the pullups that are in parallel and could cause VOL issues. This gets even worse if you load all the channels and then add another series set of switches. Some people will sequence their polling of channels to avoid this.
-Francis Houde
