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TAS5612A/14A voltage gain

Akio Ito
Genius 3595 points
Other Parts Discussed in Thread: TAS5612LA, TAS5614LA, TAS5624A, TAS5612A, TAS5614A, TAS5630B

Hi,

TAS5612LA, TAS5614LA and TAS5624A datasheet have description "The TAS56xx uses constant voltage gain" in first page.
Though TAS5612A and TAS5614A also belong to a closed loop method, their datasheet do not have the description.
Do they use constant voltage gain?

Best regards,
Akio Ito

  • 0
    TI__Genius 9175 points
    Hello Ito-san,

    Yes the TAS5612A and TAS5614A have fixed voltage gains. Since they are PWM input devices, the gain is based on the PWM modulation index which converts the PWM duty cycle into an RMS output voltage.

    These devise are designed so that with a full PWM duty cycle, the amplifier is driven into voltages clipping for full output power. Therefore, higher power (higher PVDD voltage amplifiers) have slightly more gain.

    For the TAS5612A the output voltage can be approximated by:
    (PWM Duty Cycle x 3.3) x (7.75/3.3) x 5.5 = output signal level

    3.3V = input PWM level
    7.75/3.3 = Input Voltage level translation
    5.5 = closed loop gain

    This does not account for voltage loss across the Rds-On of the output FETs or the DCR of inductors.

    Best Regards,
    Matt
  • 0 in reply to Matthew Beardsworth
    Genius 3595 points
    Hello Matthew-san,

    Thank you for the answer.
    It seems the value same as TAS5624A.
    e2e.ti.com/.../381495

    Is other TAS56xx the same gains, too?

    Best regards,
    Akio Ito
  • 0 in reply to Akio Ito
    TI__Genius 9175 points
    Hello Ito-san,

    The TAS56xx series will all have very similar gains. The TAS5630B will have the highest gain because it is the highest power TAS56xx devices. Should be around 1.5dB higher to get higher voltage with the same PWM modulation index.

    Best Regards,
    Matt