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DRV2700 driving 2 piezos out of phase

mitch meiss
Prodigy 170 points
Other Parts Discussed in Thread: DRV2700, DRV2700EVM

Is there anything similar to DRV2700 that can drive two piezo at opposite phases? I am looking to use this in the application for a piezo micro pump driver.

Thanks

  • 0
    TI__Expert 3791 points
    Mitch,

    Thank you for posting on the forums, we will look into this and get back to you.

    Best Regards,
    Javier Palomo
  • 0
    TI__Genius 10512 points
    Mitch,

    What voltage are you trying to run the piezo's at and what is the piezo capacitance?

    Regards,
    Kelly Griffin
  • 0 in reply to Kelly Griffin
    Prodigy 170 points

    Kelly,

    I am trying to run both piezos at roughly 85Vpp out of phase and at 25Hz. I am using the mp6 micropump and should cannot find the capacitance at the moment.

    mitchmp-6.pdf

  • 0 in reply to mitch meiss
    TI__Genius 10512 points
    Mitch,

    At this voltage you could hook each output (out+/out-) of the DRV2700 to each pump with the other pump terminal to ground. The output will be driven out of phase and you can achieve +/-85Vpp with the boost set to 105V. Since this is generally driven differentially, the small ripple voltage of the boost is naturally subtracted out. However, for this case there will be a small ripple voltage amplified to the outputs. Let me know if it works out or you have any issues.

    Regards,
    Kelly Griffin
    Application Engineer for Low Power Audio and Actuators
  • 0 in reply to Kelly Griffin
    Prodigy 170 points

    Perfect! I am ordering the DRV2700EVM for prototyping. So as long as I place my piezo 1 between out+ and ground and my piezo 2 between out- and ground and set the eval kit to 105V and run it at 25Hz, theoretically I should be good?

    I found out the piezos each have a capacitance of 9nF

    Thanks

  • 0 in reply to mitch meiss
    TI__Genius 10512 points
    Theoretically yes. We have not tried this, so we are excited to hear the results! Also 9nF is no problem for the DRV2700.

    Thanks,
    Kelly
  • 0 in reply to Kelly Griffin
    Prodigy 170 points

    Kelly,

    Good news. The driver works as expected and drives the mp6 micropump. From an app engineer at servoflow -- You should arrange the drive such that the drive goes negative about -10 to -20V.  This is used in actively retracting the diaphragm.  The positive voltage is used to actively compress the diaphragm.

    How would this be possible?

    Thanks!

  • 0 in reply to mitch meiss
    TI__Genius 10512 points
    Mitch,

    Great! Glad it is working. To apply a negative voltage you have to use a single driver per pump; pump hooked up across OUT+/-.
    This way the OUT+ can provide a positive voltage and then OUT- could provide a positive voltage, but since OUT- would be hooked up to the opposite terminal, the pump would see a negative voltage. Our part can't drive a purely negative voltage.

    Regards,
    Kelly Griffin