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TAS5751M: Some questions about TAS5751M(settings and tuning)

Gary Guo
Prodigy 240 points
Part Number: TAS5751M

Hi audio folks,

      One of my customer want to use the TAS5751M as the PA in TV. we showed the Demo how to use it yesterday. But customer have few questions. the question is as below.

1. TAS5751M has four bands AGL in processing. So if the power is limited by AGL4, how can I change the volume? I mean, if I change the master volume much bigger, that will cause the power over limitation. So how can I control the volume in safety way?

2. I'm not sure what's the difference between the Pre-Scale and Post-Scale? what function can I achieve by using it? do you have any documents which explain it clearly.

3. we have a feature 'Preset' in Multiband AGL. So, if I choose the "10W 19.6V PVDD 6ohm Load", does it means, no matter what I change the volume, the output power will be always limited at 10W?

4. For tuning aspect, do you have any documents which could share me?

    Thanks for your help in advance.

  • 0
    TI__Expert 6985 points
    Hello Gary! Good to hear from you and I hope you have settled into your new role?

    Also, I assume you are using the EVM with the motherboard? You should be able to control what is needed graphically simply by using the GUI, and you will be able to visualize limits. Also, much of what you may be trying to do, or avoid, is very also dependent on what level of PVDD you are applying as well as the load and its configuration. DO you have more information on that?

    For any follow on questions Zhawn can help you out, and as he is based in China he can help you during your Thursday. Thanks, Jeff
  • 0
    TI__Mastermind 24835 points

    Hi Gary,

    I can't see your pictures, pleaes click 'Use Rich Formating' to paste the pictures. Please find my answers below:

    1. TAS5751M has four bands AGL in processing. So if the power is limited by AGL4, how can I change the volume? I mean, if I change the master volume much bigger, that will cause the power over limitation. So how can I control the volume in safety way? [Shawn] With the ALG is enabled, the output amplitude is limitied when the imput level exceeds THR. I think you could refer to detailed explanation in the section 7.4.4 in TAS5751M datasheet. http://www.ti.com/lit/ds/symlink/tas5751m.pdf

    2. I'm not sure what's the difference between the Pre-Scale and Post-Scale? what function can I achieve by using it? do you have any documents which explain it clearly. [Shawn] Basically, pre-scale and post-scale blocks are used together as a function called THD manager. The THD manager can be used to achieve digitally specified THD levels without voltage clipping. This allows user to achieve the same THD (for example, 10% THD) for different power levels (15 W/10 W/5W) with same PVCC level. Please refer to the attached documents.Prescalar-Postscalar Setting.ppt

    3. we have a feature 'Preset' in Multiband AGL. So, if I choose the "10W 19.6V PVDD 6ohm Load", does it means, no matter what I change the volume, the output power will be always limited at 10W? [Shawn] In 'Preset' option, you can find some examples for AGL programming. The output power is limited by AGL THR configuration. Please refer to the introduction in TAS5751M EVM user's guide. http://www.ti.com/lit/ug/slou440/slou440.pdf

    4. For tuning aspect, do you have any documents which could share me? [Shawn] We don't have official document. Please contact me offline, I could show you some material.

    Best regards,

    Shawn Zheng

  • 0 in reply to Shawn Zheng
    TI__Mastermind 24835 points
    Gary,
    As we are communicating off-line, could you please close this question on E2E?
    Best regards,
    Shawn Zheng
  • 0 in reply to Shawn Zheng
    TI__Prodigy 240 points
    Hi Shawn,
    thanks for your kind help, your help have solved my question, really appreciate.