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TPA3251: Akira-Series: CLIP_OTW pin for power supply control

Lukas Jani
Prodigy 150 points
Part Number: TPA3251

Hey everyone,

as stated in the Datasheet of the TPA325x-Series ICs: 

10.2.1.2

Detailed Design Procedures -  The CLIP signal is indicating that the output is approaching clipping. The signal can be used to either an audio volume decrease or intelligent power supply nominally operating at a low rail adjusting to a higher supply rail.

I want to use the given signal to controll a DCDC-Boost converter in a similar manner, as the usual/suggest envelope tracking powersupplies for mobile audio do. (TI has a bunch of designs available here).

Does anyone have experience with that implmentation?

Especially interesting: when does the CLIP pin actually change state? At a given threshold from output to supply? or only, if the output would already exceed the supply? In other words --> is there time for the powersupply to react with and voltage rail increase before the amp actually goes into clipping?

Thanks a lot!

Best regards,

Lukas

  • 0
    TI__Mastermind 20830 points

    Hi Lukas,

    First it's important to define when you consider a device to actually begin clipping. Would it be at 1% THD or do you consider it sooner than that? 

    For our devices we tend to define clipping to really start at 1% since that's when the human ear is able to really detect the distortion. However with the TPA3251 device, the CLIP detection begins to trigger sooner than 1%. 

    Best Regards,

    Robert Clifton 

  • 0 in reply to Robert Clifton56
    TI__Genius 9140 points

    Lukas,

    I believe Robert's explanation is clear for you to understand how to implement envelope tracking in your application.  So i will close this topic now. If more questions, please open a new thread.

    Dylan