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TCA9548A: Does TCA9548A support slave side with 5V pull up? VCC =3.3V

Part Number: TCA9548A

Hi expert,

As title, does our device support with below power domain pull up as capture below?

VCC = 3.3V

Master side = 3.3V

Slave side = 5V

I am not able to understand the sector 9.2.1 from the datasheet, could you please help me understand more?

Thanks,

Oliver

  • Hi Oliver,

    When voltage translation is needed with this device things become a little tricky. Section 9.2.1 is mainly explaining what to set VCC as when you are performing level translation. The voltage on VCC sets the VPASS voltage of the device which clamps the bus voltages. It will essential set the lower limit to the bus voltages seen on the device.

    Figure 14 shows the relationship between VCC and VPASS:

    As you can see it is linear. So when choosing VCC you want to pick one so that VPASS is equal to or less than your lowest bus voltage. In your picture the lowest bus voltage I can see is 3.3V. So the upper limit to your VCC would be around 4.6V. A VCC of 3.3V (like you chose) would lead to a VPASS of around 2V which is lower than your lowest bus voltage. So that would be correct, the setup you have shown would work.

    Let me know if you have any further questions.

    Best,

    Chris