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DRV2700EVM-HV500 - high capacitance load

MARINA INNOCENTI
Prodigy 10 points
Other Parts Discussed in Thread: DRV2700EVM, DRV2700EVM-HV500, DRV2700

We did test your DRV2700EVM-HV500 and DRV2700EVM with our EAP type haptic actuator, with capacitance over 200nF and which should be driven at 212 Vpp (0 – 212V) with frequencies up to 150Hz.

By using the DRV2700EVM-HV500 we’re limited to 50% of duty-cycle at 20 Hz (see attached image).

Is it possible to use the DRV2700EVM IC on the evaluation board to drive the actuator in higher frequencies and duty-cycle? Maybe by changing some of the components present on the Evaluation board?

Thank you for your support

  • 0
    TI__Genius 13610 points

    Hello,

    I dont think your image uploaded properly could you please try to attach again in reply.

    Are you tring to have a square wave output from DRV2700 at 212vpp at 150Hz?

    Best,

    Carson

    Low Power Audio Apps

  • 0
    Prodigy 10 points

    Dear Carson,

    could you please access the image at the following link:

    https://i.ibb.co/MPvB1kT/TI-osc.png

     

    And yes, we tried the square wave with Eval. board software. The capacitive load is of 220nF and if we increase the frequency, the Vpp value decreases.

     

    Is there any way to update the sender including Vitaliy, whose email address is: vitaliyparkula@kemet.com?

  • 0 in reply to MARINA INNOCENTI
    TI__Genius 13610 points

    Hello,

    I am still unable to access image, can you please copy and paste.

    With EVM if boost voltage is max there is not much you can do about achieving Vpp at a certain frequency if it is out of range of the frequency response graphs in the DRV2700 datasheet.

    Best Regards,

    Carson

  • 0 in reply to Carson Allen
    Prodigy 10 points

    Hello Carson, thank you for your feedback.

    As specified initially, we’re using the DRV2700EVM-HV500 board which works in flyback mode up to 500V (described in section “9.2.5 Flyback Circuit” of DRV2700 IC).  We’re interested in using it at half of its voltage output capability, around 212V to drive our actuators of 220nF up to 200Hz frequency.

    It seems that the main culprit of low frequency operation (only 20Hz) for our 220nF actuator at 200Vpp (0 – 200V) is a high RC-time constant of the DRV2700EVM-HV500 board responsible for draining charge from the actuator.

    Is it possible to lower even more the existent RC-time constant on DRV2700EVM-HV500? Should we lower the values of R(FET1) and R(FET2) on the pulldown FET circuit (Figure 37 of the DRV2700 IC datasheet) for that?

  • 0 in reply to MARINA INNOCENTI
    TI__Genius 13610 points

    Hello,

    If you believe if it is the resistors of the flyback configuration itself affecting your performance you could possibly lower them at the risk of having major leakage current in the circuit, so I would not officially recommend it  especially with when high voltage is involved it could be a safety issue.

    Best Regards,

    Carson