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ISO1228: Can't get ISO1228 operating normally.

Part Number: ISO1228

Hi Sir:

The SPI clock frequency is 500KHz and voltage level is 5V.

Waveforms measured as below.

The input SPI reads the IN1~8 values ​​according to spec..

But there is no output from SDO.

The circuit is as follow.

Please help to suggest if we can do more tests to clarify what is the root cause that it's not working properly.



  • Hi Kyle,

    Thank you for your question.

    The Schematic seems to not follow the datasheet guidelines. Please consider including Rsurge, Csurge, Rilim (unless it is 0 ohms), Cfil, Rpar, decoupling capacitor for VCC1, and others. Please refer to example schematic below:

    Please consider these changes from the guidelines in the datasheet and test again.

    Aaditya Vittal

  • Hi Aaditya:

    Thanks for your answer.

    We have tried adding the Rsurge and Cfil.

    But now the problem is that we can't read any register value from SPI interface.

    And it seems that when power on, nINT is not in high state.

    And when we send SPI commands, nINT is not responding as well.

    Now we are focusing on SPI transmitting. Not yet doing the DI test.

    We expect to see any response through SPI. But we get nothing.


  • Hi Kyle,

    Thank you for your response.

    Aside from the Rsurge, Csurge, and Cfil, the Rpar and the decoupling capacitor are extremely important for the function of the device, as mentioned in the datasheet. Please implement these components as per the datasheet and please attach an updated schematic. Once the schematic has been updated, please test again and let us know.

    Aaditya Vittal