PCA9548A: Level translation between 1v8 and 3v3. what Vcc is suggested?

Hey Jason,

The issue with this is the Vcc of the PCA9548A is connected to 3.3V (pin 24). Looking at the main SDA/SCL, it is 1.8V. Doing the math to calculate the ViH for the switch comes out to be 2.3V (3.3V * 0.7) therefore 1.8V is lower than 2.3V so the device will never actually see a logic high and the switch will never be enabled. This means with how you currently have it set up, it will NOT work.

Is it possible for you to change to TCA9548A? The PCA version supports only up to 2.3V on Vcc (pin 24) while TCA9548A supports 1.65V which means you can switch Vcc from 3.3V to 1.8V and this switch would work (TCA will work with 1.8V on pin 24).

If you need to use the PCA for whatever reason, then you will need to supply a lower Vcc (pin 24) such as 2.3V. {2.3* 70%=1.6V which is lower than 1.8V so this will work}

Thanks,
-Bobby