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TAS5766M: Question about volume control

Satoshi
Guru 19575 points
Part Number: TAS5766M
Other Parts Discussed in Thread: TAS5760M

Please let me check about two points below volume control for TAS5766M.

①Volume control range is described -110dB ~ 6dB by datasheet P32 and -103dB ~ 0dB by slaa653a application note P8, which is correct?

②About control register Page-0 Register-61 and Page-0 Register-62 (by slaa653a application note), are reserved bits mean over 0dB setting?

　For example, is 00101111 same as +0.5dB? 

 

【Background】

Customer want to use +24dB volume on TAS5766M.

By the way, can TAS5760M set +24dB? (by datasheet page-44)

Best regards,

Satoshi

  • 0
    TI__Expert 6985 points
    Hello Satoshi-san! Roy can help you with your question. Thanks, Jeff
  • 0
    TI__Genius 9300 points

    Hi Satoshi,

    If you take a look at the App Note "PurePath™ Smart Amp User Manual (TAS5766M/68M)" under "MySecure Software" after logging in to ti.com, you will be able to find some information that explains your questions in Section 5.4. I have also summarized it below:

    1. The range "-110 ~ +6 dB" belongs to the "Pre-processing" part and can be adjusted from the gain slider in PPC3. Although the spec show that the maximum is +6 dB, you may have found that it can be increased up to +18 dB. That is because another internal block of TAS5766M helps boosting up the gain value.

    The range "-103 ~ 0 dB" belongs to the "Post-processing" part and can be adjusted at Page 0 Register 61/62.

    2. Yes, the reserved bits are for over 0 dB settings. However, adjusting this parameter requires more attention on System Gain Calibration and you also need to make sure that the resulting peak output voltage does not exceed the supply voltage. (Please refer to P.31,32,35 of the App Note).

    3. Yes, TAS5760M can support up to +24 dB of volume. 

    Best regards,

    -Roy Hsu

    Texas Instruments

  • 0 in reply to Roy Hsu
    Guru 19575 points
    Roy-san

    Thank you for reply,

    About your answer No.2, slaa653a is described "reserved" and TAS5766M datasheet is not described Page-0 Register-61/62 in and of itself.
    Is there background (or reason) for resister-61/62 map not volume bit but above described?

    Best regards,
    Satoshi
  • 0 in reply to Satoshi
    TI__Genius 9300 points

    Hi Satoshi,

    Most customers found that setting both "DAC Fine Digital Gain Control" and "Power Stage Gain" would be enough to fulfill their requirements.

    That's why we did not include that in the datasheet.

    If you really need to adjust these registers, be sure to do the system calibration so the device will be able to know the actual gain of the system.

    Thank you.

    Best regards,

    -Roy Hsu

    Texas Instruments