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UCD3138 - Using EMeter Library under DC Input

CF.
Prodigy 150 points

Hi,

I would like to know if EMeter library works under DC input?

Do i need to modify anything in the PFC program to make it work under DC input?

CF. Lee

  • 0
    TI__Expert 7330 points

    Hi CF,

    Yes, it works for DC input also, there is no modification needed.

    Regards,

    Bosheng Sun

  • 0 in reply to Bosheng Sun
    Prodigy 150 points

    Hi Bosheng,

    Emeter library should be taking account of emi filter current in its calculation. Wouldn't it be affecting the result in DC in light low?
    And i also found that the slope of meter reading of Iin vs ADC reading of Iin is having two different slope when the PSU is under DCM and CCM.
    Could Emeter library deal with this problem??
    Thanks.

    CF.Lee

  • 0 in reply to CF.
    TI__Expert 7330 points

    Hi CF,

    The library already takes care of DC input, don't worry about that. To save calibration time in mass production, only two calibration points are required, one is at low load, the other is at heavy load, the assumption is that Iin vs ADC is linear. This assumption is true if there is no noise, however, the signal to noise ratio is bad at light load, that's why you saw the slope is different. Adding more calibration points can help the accuracy, but this will increase the calibration time. This is a tradeoff we have to make.

    Regards,

     Bosheng Sun