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Original question:

DS90UB954-Q1: 914's operation when releasing clock stretch of I2C

DS90UB913A-Q1：When PCLK Mode , I2C Reverse channel update the camera firmware

Waber Huang
Prodigy 150 points
Part Number: DS90UB913A-Q1

 913 work on PCLK mode

TX:913A

RX:914A

I use DS90UB913A-Q1 I2C Reverse channel update the camera firmware,but sometimes I2C will be lost, causing the firmware update to fail.

I prepare 10 samples to test. But found 5-6 pcs I2C have Issue.

If I swap the normal module with the 913 of the exception module, the I2C problem will follow.

  • 0
    TI__Guru** 108100 points
    Hi,

    what do you mean by "If I swap the normal module with the 913 of the exception module, the I2C problem will follow."?

    Can you monitor LOCK on 914A and see if the LOCK also goes low at the same time?
    Can you monitor the power supply pins on the 913A and see if any relation?
  • 0 in reply to Hamzeh Jaradat
    Prodigy 150 points
    Hi Hamzeh
    what do you mean by "If I swap the normal module with the 913 of the exception module, the I2C problem will follow."?
    -->If I switch the 913 IC that works correctly to the abnormal camera module, this will make the I2C loss disappear.
    So,i think 913 is the source of the problem.

    Can you monitor LOCK on 914A and see if the LOCK also goes low at the same time?
    -->The LOCK Keep High

    Can you monitor the power supply pins on the 913A and see if any relation?
    -->The Power supply pins are Normal
  • 0 in reply to Waber Huang
    TI__Guru** 108100 points
    Hello Waber,

    if you believe this is a device issue, please contact you local TI sales representative.
  • 0 in reply to Hamzeh Jaradat
    TI__Genius 11635 points

    Hi Hamzeh,

    I work with Waber and confirmed the issue is cause by POC power interference to the back channel. We discuss connect the POC and use external power source. The issue disappear. Would you help review our POC circuit attached below, any improve suggestion?

  • 0 in reply to PYTsai
    TI__Guru** 108100 points

    Hello PYTsai,

    thanks for the info.
    Yes your PoC filter is not sufficient for Back channel frequency because it is messing the large Inductor. Please refer to this application note.

    Also you can remove the Common Mode Choke because you are not using differential. Also you need to replace the FB with one with higher Impedance at high frequency, 1.5K ohm @ 1GHz