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PCA9544A: SDA pin is pull low by IC after power up in -10C ambient temperature

KevinZhang123
Expert 5750 points

Part Number: PCA9544A
Other Parts Discussed in Thread: TCA9544A

Hi, Team

My communication customer is using PCA9544A in their BBU product. The PCA9544A works correctly in room temperature.

They find that when system is power up in -10C ambient temperature, PCA9544A will pull SDA pin low. That makes communciation arbitration error in processor (I2C master). Only clock signal is sent to SCL pin, the SDA will back to normal.

Is there any suggetion on this issue? Could you help to fix this issue?

CH1 (Yellow): SCL

CH2 (Green): SDA

Thanks

Kevin

  • 0
    TI__Guru* 81641 points
    Hey Kevin,

    Can you provide waveforms of Vcc when you power on the device?

    From what it looks like, you have a stuck bus which could be related to how the device powered on (bad power on reset).

    "Is there any suggetion on this issue? Could you help to fix this issue?"
    When we see this, typically you can resolve this by sending 9 or 18 clock pulses on SCL to recover the bus. You could send this signal after each start up to ensure the bus is free.

    You may want to take a look at section 11.1 of the datasheet to see the power on requirement of this device. Another suggestion is swapping out the PCA9544A with our TCA9544A which has more relaxed timing requirements for the power on.

    -Bobby