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DRV8432 Noise problem

Frank Shieh
Prodigy 200 points
Other Parts Discussed in Thread: TAS5261, TAS5086

HI,  I am using DRV8432 as in following ckt. But I always got a 0.5Vpp 384k Hz noise at OUT-A and OUT-B, even I fed the DRV8432 with 50% duty cycle PWM signal form a signal generator(The PWM generator IC used is TAS5086). If I increase the capacitance of C20,C77 to 470uF then the noise level will down to less then 100mv. The problem is that when the C20/C77 value is increased, the current drawn by C20/C77 also increase when the AMP frequency increases. I need to drive this AMP up to 10Khz. I use TAS5261 in another project using similar paralleled output   and it does not have the 384Khz noise. And suggestions to  minimize the noise?

  • TI__Guru 55605 points

    Frank,

    What is your application for this circuit?  Is it a high inductance motor load or something else? 

    I am asking since this switching frequency, 384kHz, is extreme for a motor application and will certainly lead to higher switching losses as you noted.  The noise you are seeing is just the ripple in the filter. 

    The inductance is larger on the TAS5261EVM board, so maybe that is why you are not seeing as much ripple there.

  • in reply to Ryan Kehr
    Prodigy 200 points

    HI, Yes, it's a high inductance motor about 1mH  and 2.5 ohm load. I'm trying to increase the L1,L3~5 to see how much the noise can be cut down.