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ISO1540 / Pulse skipping under noisy VCC and GND condition

S.Satoshi
Guru 21675 points
Other Parts Discussed in Thread: ISO1540

Hi All,

Now our customer has evaluated ISO1540 on their prototype, but then they confirm the abnormal behavior. Output CLK from SCL2 is skipped though CLK is input to SCL1 correctly. This behavior is confirmed when the load current at DC/DC converter on the same board is heavy, so the VCC or GND line may be noisy. 

Please see the waveform below.

5875.ISO1540 pulse sikipping.pdf

[Question]

Is it possible that the noise on VCC or GND will be the cause of such pulse skip?

 

Your advice will be appreciated.

 

Best Regards,

Sonoki / Japan Disty

  • 0
    TI__Intellectual 1815 points

    Sonoki-san,

    Which VCC and GND are noisy is it VCC1,GND1 or VCC2,GND2. Is it possible to capture and send the VCC1 and VCC2 also along with SCL1 and SCL2. How much is the ringing noise in the VCC, is it going below the rated voltage rande.

    Regards,

    Sarangan Valavan

  • 0 in reply to SaranganValavan
    Guru 21675 points

    Hi Valavan-san,

    Thank you for your response. I do not have the waveform of VCC1 and VCC2, but I have additional information as below.

    • They are using ISO1540 in the AC/DC converter, so it's used in noisy condition.
    • They tried to add 100pF between GND1 and GND2, then the behavior was resolved.

    Can you confirm that similar issue has been asked due to noise on VCC or GND?

     

    Best Regards,

    Sonoki