• State Resolved
  • Locked Locked
  • Replies 3 replies
  • Subscribers 34 subscribers
  • Views 529 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

TCA9548A: Question about pull-up voltage

Silvia Gao
Prodigy 170 points
Part Number: TCA9548A

Hi team,

In the customer's application, there are two common-ground 3V3 power supplies in the system. They are "P3V3"(main power supply) and "P3V3_STBY".

For TCA9548APWR, VCC is connected to "P3V3_STBY", input channel SDA and SCL are pulled up to "P3V3_STBY", but 8 output channels SD [0:7] and SC [0:7] are pulled up to "P3V3"(main power supply).

They are wondering does the input pin leak to the output pin. (Does "P3V3_STBY" leak to "P3V3" through TCA9548APWR?)

Best Regards

Silvia Gao

  • 0
    TI__Guru 73181 points

    Hi Silvia,

    You mean if Vcc of our device is unpowered and other pins like SDx/SCx or SDA/SCL are pulled up to a voltage? If so, no back biasing should occur. leakage current will be limited.

    -Bobby

  • 0 in reply to BOBBY
    TI__Prodigy 170 points

    Hi Bobby,

    I mean if Vcc and SDA/SCL (input pin) are connected and pulled up to a same voltage(P3V3_STBY), and SDx/SCx(output pin) are pulled up to another voltage(P3V3), is there any leakage current from P3V3_STBY to P3V3?

    Best Regards

    Silvia Gao

  • +1 in reply to Silvia Gao
    TI__Mastermind 47748 points

    Hi Silvia,

    The functional block diagram shows that back powering current would be limited. 

    Connections between I2C SCL/SDA and SCx/SDx channels would be high impedance. Input filter presents high impedance input. High impedance exists between the drain/source of the internal passFET and the gate input from the switch control logic. Back powering current would be minimal. 

    Regards,

    Tyler