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TPA3251D2 Clipping

Mike Tripoli
Genius 3295 points
Other Parts Discussed in Thread: TAS5613, TPA3116D2, TPA3116D2-Q1

Hi,

I'm curious as to how the TPA3251D2 handles clipping. Another device (too small for use in this project, but a device I like very much) the TPA3116D2 uses a "compressor" style of "clipping" (using shorthand for these terms, in light of the fact that the '16D2 doesn't actually clip). How does the '51D2 handle clipping? There isn't anything in the data sheet describing what happens during clipping. I've used the TAS5613 before, and I could swear that that device used the same kind of "compressor" style clipping, but the data sheets (now?) don't mention this as well.

Thanks,

Mike T.

  • 0 in reply to Mike Tripoli
    TI__Guru** 100965 points
    Hi Mike,

    My colleague will comment later.
    TPA3116D2 has a limiter function. You set a voltage level at PLIMIT (Power Limit) which will control the maximum output voltage, it's something similar to have a lower voltage supply rail.
    TPA3251D2 has a Clipping Warning at CLIP_OTW' pin. This signal can be used by a uC or uP to reduce the volume or increase the supply voltage rail (in case the device is operating at a nominally low voltage rail) so the limiting is not implemented inside the TPA3251D2.

    Best regards,
    -Ivan Salazar
    Texas Instruments
  • 0
    TI__Prodigy 475 points

    Hi Mike,

    Clipping recovery of the TPA3251D2 is very smooth, without rail-sticking. As Ivan mentioned, a compressor (or power limiter) is not used. The plot below shows clipping at various levels of overdrive (Vin peak 2.5V, 3V, 3.5V, 4V).

    The green waveform is the pre-filter PWM switching output. The low density pulses during clipping are inaudible and perform a bootstrap refresh function.

  • 0 in reply to Jeff Berwick
    Genius 3295 points

    Hi Jeff and Ivan,

    Thanks very much for your reply. This is a great help in understanding the "clipping" characteristics of this device. "Visually" this looks very similar to the "power limit" capabilities of the TPA3116D2-Q1 device. I purchased the TPA3116D2-Q1 EVM and, though lower output power, will most likely use this device in my design. I plan to take advantage of the PLIMIT control in my design. Should I need more power I will look to the TPA3251D2. 

    Perhaps a graph as shown could be included in a next gen of the data sheet? As it stands now, there is a "mention" of clipping, but not much more.

    Thanks again,

    Mike T.

  • 0 in reply to Mike Tripoli
    TI__Prodigy 475 points

    Mike,

    I'm glad the information on clipping was helpful. I will forward your request to add clipping waveforms to the TPA3251D2 data sheet.

    If your future needs include some power level between TPA3116D2-Q1 and TPA3251D2, there is a new pad-down device in the TPA325x family called TPA3250D2  that can supply 70W per channel into 8 Ohms.

    Regards,

    Jeff Berwick