• State TI Thinks Resolved
  • Locked Locked
  • Replies 3 replies
  • Answers 2 answers
  • Subscribers 31 subscribers
  • Views 469 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

TAS5624A: Dynamic PVDD

TBK
Prodigy 120 points

Part Number: TAS5624A
Other Parts Discussed in Thread: TAS5624, , TAS5825P

Hi,

I am using dynamically control PVDD supply to TAS5624 ( class G supply method). This dynamic PVDD is controlled by output of AMP CLIP signal of TAS5624 to control the feedback of boost converter that supply TAS5624 PVDD. My lower PVDD is around 17V and higher PVDD is 36V.

When the output signal reach near clipping, the AMP CLIP will start to turn "LOW", then my PVDD move to higher voltage. My amp configuration is 2.1. 2CH for front speaker which is single ended(SE) configuration and woofer as BTL. 

During the supply from low supply switch to higher supply, the SE channel output will clip for about 23ms. After some study,  I found out that the output clip during supply switching is due to TAS5624A output bias level( PVDD /2 )  react slowly compare to the PVDD.  PVDD takes 2-3ms to raise from Low to High, but the AMP output takes 20 ~ 30ms to raise the bias to PVDD/2 which cause clipping at low side of signal.

 

May I know the why the Bias of AMP output raising slowly as compared to the PVDD raising speed?

Besides, do you have recommend High power class d amp (150W above per BTL) that support dynamic PVDD ( whether is Class H or Class G supply) without happen any clipping during supply switching?

Thank you

  • 0
    TI__Mastermind 19080 points

    Hi,

    First of all, the ramping rate of the audio output depends on the audio input. You may also monitor your input to verify. 

    Secondly, we don't have high power audio amp that could support class-H or G. You may build an external control loop to sense the audio output and dynamically change the supply voltage. Another approach is using TAS5825P which supports class H, while still using TAS5624 to output the audio power.

    Thanks!

    Regards,

    Sam

  • 0 in reply to Sam(MPAA) Zhang
    Prodigy 120 points

    Hi , Sam,

    I have tried using AMP output signal to pass through some attenuate resistor to drive my boost converter feedback to achieve dynamically change the PVDD. However the result still the same, which is the output bias of the TAS5624 react slowly cause some clipping at one side for some millisecond.

    Could you advise how to combine 2 Class D Chip( TAS5825P + TAS5624) to achieve Class-H design? do you have any application note?

    Thanks

  • 0 in reply to TBK
    TI__Mastermind 19080 points

    Hi,

    We don't have app note to introduce this idea. 

    Basically, the audio signal is accepted by the TAS5825P. The PVDD could be 5V. You may use its output to drive the TAS5624A, which accepts the PWM type audio input. Be careful with the input range of INPUT_X pin, which only supports 3.3V voltage level. So a level shifter may be required here. Also, BD modulation should be used on TAS5825P.

    TAS5825P could generate a PWM output based on the look-ahead audio content, so there won't be any clipping in the Class H control, improving your listening experience.

    Thanks!

    Regards,

    Sam