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TAS6754-Q1: about Gain

kenji gemma
Prodigy 90 points
Part Number: TAS6754-Q1

Tool/software:

Hello, Team,

Please explain the meaning of “Gain 28V/FS” in the datasheet.

“TEST CONDITIONS” states “Peak output voltage at full scale digital input.”
Since it's “full scale digital input,” this corresponds to a 0dBFS input signal.

Simply calculating the output power at 28Vpeak yields 24.49W @ 4 ohms.
This value does not appear to match the value listed under “OUTPUT POWER”.

How should we interpret this Gain value?
Which value does 28Vpeak represent?
Is it the value before the LC filter?
Or is it the value after the LC filter?

Regards,
Kenji Gemma

  • 0
    TI__Mastermind 45085 points

    Kenji,

    Your 24.49W calculation is based on a 28Vpp voltage and not a 28Vp voltage. 

    28Vp / 1.414 = 19.8Vrns

    19.8Vrms * 19.8Vrms / 4 ohms = 98W max

    We are voltage limited, so the amplifier will voltage clip before it can reach these power values.

    Regards,
    Gregg Scott

  • 0 in reply to Gregg Scott
    Prodigy 90 points

    Hi Gregg-san,

    Thank you for your reply.

    It seems our calculation approach was incorrect.

    We assumed it was BTL based on the “TEST CONDITION” and thus judged it to be Vpp.

    From your information, we understood the measurement point to be the AMP output after the LC filter.

    Even if the Gain value changed from 28Vp to 26.3Vp, we believe the “OUTPUT POWER” specification would remain effectively unchanged due to the voltage limitation.

    26.3Vp / 1.414 = 18.6Vrms

    18.6Vrms * 18.6Vrms / 4 ohms = 86.5W max

    Thank you as always.

    Kenji Gemma

  • +1 in reply to kenji gemma
    TI__Mastermind 45085 points

    Kenji-san,

    You are correct on your statement about gain.

    Regards,
    Gregg Scott