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ONET4291VA: Serial interface

Part Number: ONET4291VA

Hello,

I'm working on my first design with a ONET4291VA, and I have trouble setting the modulation and bias currents. I suspect that the issue lies with the i2c-like serial interface, since there are no other connection to the microcontroller other than the DISABLE line (which I keep low). Please take a look at the attached screen-shot of the two bus lines - I labelled them with what I expect them to do.

The datasheet mentions maximum rise and fall times of 10ns - is this correct? It seems demanding on an open-drain output.

Thank you and best regards,

Hauke 

  • Hi Hauke,

    Can you please check if the control register bit ENA (bit 7 of register 000b) has been set to 1? For the ONET4291VA to be enabled, ENA bit should be 1 along with keeping the DIS pin low.

    And yes, the clk/data rise and fall time max is 10 ns.

    Thanks,

    Sri

  • Hi Sri,

    thank you for your answer. I solved it now - the STOP-condition was not implemented correctly. In the standard i2c protocol, a rising edge of SDA while SCK is high constitutes the STOP condition. With the ONET4291VA, it seems that the rising edge of SDA must follow a rising edge of SCK (no additional falling edge of SCK is allowed)

    Best regards,

    Hauke