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TPS23881: Power reading accuracy

Delaney Berger
Intellectual 2475 points
Part Number: TPS23881

Hi Team, 

Could you please explain the accuracy margin for the power readings of the TPS23881? From the datasheet, it is clear that TPS23881 has 2% current sensing accuracy and section 7.5 shows the min and max values for voltage and current reading accuracy margins, but I want to make sure I understand the readings. 

Using voltage scaling factor of 3662 and current scaling factor of 89500 when calculating the power being delivered on a channel. When testing a class 5 PD in Sifos and set the powered load at PSE to 45W, the calculation based on V and I from 0x30 and 0x32 registers reads ~46.3V which is >2%.

Thank you, 
Delaney

  • 0
    TI__Genius 15685 points

    Hi Delaney,

    The voltage reading accuracy is 2.5% and current reading accuracy is 2-3%, so the power accuracy should be >2%.  If you look at the datasheet, the PCUT accuracy is shown below. 

    In your system, there's also power loss on the cable. So 46.3W is reasonable to me. Thanks. 

    Best regards,

    Penny