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ISO1541: Input/Output Problem

Brian Wang0928
Genius 11610 points
Part Number: ISO1541
Other Parts Discussed in Thread: ISO1540

My customer found the waveform with ISO1541 is not correct as below. However, when SCL2 is disconnected to uC, the waveform can become normal. it looks there is load effect with the signal outputs.

Could you help on this! Very thanks 

Ch1: SCL1, CH2: SCL2

. 

  • 0
    TI__Mastermind 49415 points

    Hi Brian,

    Sorry to hear about the issue.

    I am assuming the upper waveform is CH1:SCL1 while the lower is CH2:SCL2. This is strange and not expected to happen from ISO1541 for a good device. Could you please share a larger schematic showing the devices with part numbers & connections on both sides of ISO1541? Could you please also share the PCB layout for the same? If these details cannot be shared on E2E, then please do email them to me.

    Do you know if this happened on one board and with one device or did customer observe this on multiple boards and devices?

    Regards,
    Koteshwar Rao

  • 0 in reply to Koteshwar Rao
    TI__Genius 11610 points

    We tried to use two ISO1541 for the bidirectional CLK signals. the problem is solved. it looks customer needs to use ISO1540. 

  • 0 in reply to Brian Wang0928
    TI__Mastermind 49415 points

    Hi Brian,

    Glad to know that customer was able to fix the issue. If customer is implementing clock stretching then the ISO1541 with only one bidirectional channel will not support it, customer would be required to use ISO1540. I am not sure if that was the cause is but glad to know that it is fixed by using ISO1540. Thanks.

    Regards,
    Koteshwar Rao