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DRV2700: Output ripple problem

Anna
Intellectual 920 points
Part Number: DRV2700

Hi Dear,

Our customer uses DRV2700, the load is piezoelectric ceramics, and the hardware is made according to the reference design of DRV2700EVM-HV500.

The output scheme is selected as shown in the following figure.   After testing, the ripple at the output end is too large, even nearly 20V, may I ask if there is any way to reduce the ripple?

  • 0
    TI__Genius 17280 points

    Hi Anna, 

    By the nature of the boost converter there will be some ripple on the output. We wont be able to support optimizing the design beyond what is available on this EVM.

    The simplest solution to remove this ripple would be a low pass filter to be used on the output.

    Regards,
    Arthur

  • 0 in reply to Arthur Brown
    Intellectual 920 points

    Hi Arthur,

    The back end of the circuit is light load, working in DCM mode, requiring 0-150V adjustable, and the response should be fast, if the back end adds too many filters will cause the response speed to slow. Are there any other suggestions to improve the ripple?

  • 0 in reply to Arthur Brown
    TI__Intellectual 2675 points

    Hi Arthur,

    I'm Tess, local FAE to support this case. We understand that ripple is a tradeoff for fast response and output capacitance. But 20V is still too much for us. Do you have any suggestion for proper capacitance value on EVM?   

    If DRV2700 could not meet need, do you have other available device to recommend? Requirement: <24V input to drive 0-150 output voltage and 7uF piezo ceramic load.  Low power, small size and lower ripple are preferred. 

    Thanks a lot for the help.

    Best Regards,

    Tess Chen

  • 0 in reply to Tess Chen
    TI__Genius 17280 points

    Hi Tess, Anna, 

    The output capacitance could be increased to minimize the ripple. Id recommend reading section 8.2.5 in DRV2700 datasheet. 

    However the response time for a 7uF piezo will be quite slow. I suspect that even a 10Hz tone at 150Vp will be not possible. 

    We do not have any other devices capable of 150Vp.

    Regards,
    Arthur