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TPA2029D1: Changing/ setting the gain on TPA2029D1

Peter Tentchev
Prodigy 40 points
Part Number: TPA2029D1
Other Parts Discussed in Thread: TPA2028D1, TPA2017D2

Hi,

How could I change/ set the default gain of the TPA2029D1?

What does it depend on?

Thanks in advance.

BR

Peter A. Tentchev

  • 0
    TI__Guru* 84915 points

    Hi, Peter,

    Welcome to E2E and thank you for your interest in our products!

    The TPA2029D1 has an automatic gain compensation algorithm that can be enabled based on the logic level at the AGC1 and AGC2 pins. When this feature is not enabled, the device has a 1:1 gain. Compared with other amplifiers, the gain can only be set by the AGC. As stated in the datasheet, the AGC has a fixed gain of 9dB and an output limiter of 9dBV. The gain is automatically modified when the input level is adjusted.

    https://www.ti.com/lit/ds/symlink/tpa2029d1.pdf#page=10

    Please let me know if you have additional questions or comments.

    Best regards,
    Luis Fernando Rodríguez S.

  • 0 in reply to Luis Fernando Rodriguez S.
    Prodigy 40 points

    Hi Luis,

    Thank you for your quick response. 

    We need to limit the output of the circuit with TPA2029D1 to 1Vrms. The input signal will be 1Vrms but may have peaks.

    I imagine that we have to enable AGC, but could you please suggest if necessary to put both AGC1 and AGC2 to log.1?

    If in this case if the gain = 9dB, we can lower the input signal adequately or attenuate the output signal before another power amplifier (we are thinking of using TPA6211A1DGNR) that will output the audio to large audio line similar to UIC568 (railway).

    Could you please recommend us the settings of the TPA2029D1 and/or the circuit?

    Thanks in advance.

    Best regards,

    Peter A. Tentchev

  • 0 in reply to Peter Tentchev
    TI__Guru* 84915 points

    Hi, Peter,

    Unfortunately, I think the TPA2029D1 won't be the best device for your application. The AGC settings are fixed in this device. The gain is fixed to 9dB but the limiter level is also set to 9dBV, which limits the output to a peak output voltage of ~4Vp (1W for 8ohms load).

    If you are looking for a similar device, I would recommend the TPA2028D1, which allows to configure the AGC settings through I2C.

    Please let me know if you have questions or comments on this.

    Best regards,
    Luis Fernando Rodríguez S.

  • 0 in reply to Luis Fernando Rodriguez S.
    Prodigy 40 points

    Hi Luis,

    Thank you very much.

    We are thinking of exploring TPA2028D1 and will purchase TPA2028D1YZFEVM.

    I have a question: using the TPA2028D1  Software GUI Interface would we be able to write the configuration to the EEPROM?

    I ask you that because the final circuit will not have a host MCU and should be configured from the pre-programed EEPROM.

    Thanks in advance.

    Best regards,

    Peter Tentchev

  • 0 in reply to Peter Tentchev
    TI__Guru* 84915 points

    Hi, Peter,

    Unfortunately, you would require of a host processor capable to configure the TPA2028D1 through I2C on each power up sequence.

    Do you require a full hardware controlled device? Could you share the key specifications that you require for this device so we can suggest the best device for you?

    Thank you.

    Best regards,
    Luis Fernando Rodríguez S.

  • 0 in reply to Luis Fernando Rodriguez S.
    TI__Guru* 84915 points

    Hi, Peter,

    Do you have additional details about this? Could you take a look at my previous post?

    Best regards,
    Luis Fernando Rodríguez S. 

  • 0 in reply to Luis Fernando Rodriguez S.
    Prodigy 40 points

    Hi Luis,

    Thank you for your reply,

    We need to limit the amplitude of audio signal along the analog bus to 1Vrms (0dbV).

    I send you the link pf Reference Design - AN-934 60 dB Wide Dynamic Range, Low Frequency AGC Circuit Using a Single VGA Application Note (Rev. 0):

    AN-934 60 dB Wide Dynamic Range, Low Frequency AGC Circuit Using a Single VGA Application Note (Rev. 0).pdf

    Does TI have similar devices and  Ref. Designs?

    If yes, please send me the links.

    Thanks in advance.

    BR

    Peter A. Tentchev


  • 0 in reply to Peter Tentchev
    TI__Guru* 84915 points

    Hi, Peter,

    We have multiple devices that support AGC, but the most part of them require of I2C control. The TPA2028D1 actually supports an output voltage limiter that can be from -6.5dBV to 9dBV.

    The only hardware controlled devices that support AGC are the TPA2029D1 and TPA2017D2. But they can be only limited to 9dBV.

    Best regards,
    Luis Fernando Rodríguez S.