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PCA9546A output dissable issue

daniel
Genius 5095 points
Other Parts Discussed in Thread: PCA9546A

Hi,

My customer use PCA9546A to do a I2C bus switch, and the channel will be disabled when the channel is non-used after 1s.

Customer used the same control code to the other factory IC, and won't happen this issue. Please help to clarify it. Thanks.

Below picture shows, they switching the PCA9546A to enalbe ch2.  (G2_SDA/SCL: input,  Riser2_SDA/SCL: ouput,  and Mux addr: 0xE0)

After 1s, there is no input data changed but output data will pull low 2s. And the channel will be disabled.

Schematic

  • 0
    TI__Intellectual 2175 points

    Hi Daniel,

    From the description of the issue it seems like the PCA9546A is resetting and going into default register state of all channels disabled. 

    Do you know what causes the RISER2 to pull-down after 1s? Is it a possibility that the VCC also pulls/glitches down at that instant? A glitch on the VCC below the power-on reset threshold can reset the PCA9546.

    Thanks,

    Rajan