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TCA9803: Pull on B Side, Causes Issue

Ramakrishna Raja C
Prodigy 40 points

Part Number: TCA9803

Hi Team,

I have connected a I2C bus with 4.7k PU on A side, accidently I have mounted a 10k PU on B side as well.
As per datasheet B side has some current source.

When 10k was mounted my SoC reset/watchdog was not released many interfaces failed due to this.
After removing the 10k PU on B side my SoC returns back functional.

Was wondering why this happens?

  • 0
    TI__Guru 54671 points

    Hello,

    TCA9803 has a current mirror on B-side that helps the device to realize what direction the I2C signals are going to/from. The internal current source is sensitive to additional current sources such as pull up resistors. It is stated in the footnote of Section 9.2 Functional Block Diagram, and 9.4.1.1 B-Side Input Low (VIL/IILC/RILC)

    Regards,

    Jack