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Can DRV8662 Drive Loads in the 10uF Range?

Charles Gervasi
Expert 2270 points
Other Parts Discussed in Thread: DRV8662

Is the DRV8662 at all appropriate for driving large piezos with 10uF loads?  We want to get to the 150V range at 30kHz. 

I know DRV8662 will not do this, but I'm wondering if I can use it at all, perhaps at a lower frequency and voltage, with a 10uF load.  How can I calculate the limitations of DRV8662 driving a load this large?

  • 0
    TI__Genius 9670 points

    Charles,

    Unfortunately the DRV8662 will not support that large of load at 150V.  At 150V it can support about 50nF of capacitive load up to about 1kHz.

    The DRV8662 can deliver at it's peak about 50mA to the load. You can estimate the maximum current your load will need based on the equation below.

    Let me know if you have any questions.

    Thanks,
    Brian

  • 0 in reply to Brian Burk
    Expert 2270 points

    Brian Burk said:

    Charles,

    Unfortunately the DRV8662 will not support that large of load at 150V.  At 150V it can support about 50nF of capacitive load up to about 1kHz.

    [snip]

    Thanks for the quick reply.  That's exactly what I thought!  Do you know how people who need to drive large currents at high voltage into these piezo stacks do it?  Maybe they boost the voltage and use high-current switching transistors.

  • 0 in reply to Charles Gervasi
    TI__Genius 9670 points

    Charles,

    I have typically seen people use a discrete solution to handle large loads like 10uF.  The biggest limitation of a integrated solution is the current and resulting thermal dissipation on chip. 

    We are investigating devices that can support larger loads, but 10uF is very large at 1kHz. It makes more sense to start from a discrete solution so that you can manage the currents and thermal dissipation from a system level.

    Thanks,
    Brian