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TPA3112D1: What number is used for RS in eqn 1 on page 13 in the datasheet

Lauren Mayfield
Expert 7180 points
Part Number: TPA3112D1

My customer is not able to get the same answers from the equation 1 that are in Table 2. 

I am trying to replicate their calcuations - but I don't see what number was used for RS. 

Can you clarify how you arrived to the numbers in the table? It doesn't add up in our calcuations.

  • 0
    TI__Mastermind 19250 points

    Hi,

    The calculation is also considered the Rds(on) loss and trace DCR loss. And the data on the table is actual data we captured on EVM board, not only calculation.

    Since 4*PLIMIT(4*6.97V) > PVCC, so there is no limitation for output peak voltage. Vin=1Vrms, so Vout rms is 10Vrms, but considering Rds loss,(Rds=0.24ohm) , the Po on load should be (10^2/(4+0.24))*4/4.24= 22.25W if do not consider trace loss.

    And Vp should be (10*4/4.24)*1.414,if do not consider trace loss. Vpp is 2*Vp

    As I marked, the data is captured on EVM board, so trace DCR loss is considered.

    Regards,

    Derek

  • 0 in reply to Yanming Gong
    TI__Expert 7180 points

    When doing your calculations, they want to know if you used P = V^2/R to calculate your power results? Or it must be P = V*I since you accounted for trace lost, correct?

    Thanks,
    Lauren

  • 0 in reply to Lauren Mayfield
    TI__Mastermind 19250 points

    Hi Lauren,

    I used P=V^2/R to calculate the power, the V is RMS value. 

    Regards,

    Derek