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DRV8838: PWM Input in PH/EN Pins

Daiki Noguchi
Prodigy 10 points
Part Number: DRV8838
Other Parts Discussed in Thread: DRV8837

Tool/software:

I want to test whether I can drive a piezo element using the DRV8838.

I would like to generate a driving waveform in which each cycle outputs positive voltage, negative voltage , and 0V in sequence (overall frequency: 50–100kHz).

Question: If I input PWM signals with different duty cycles to the PH and EN pins to create this waveform, will there be any issues with the IC?

  • +1
    TI__Mastermind 45425 points

    Hi Noguchi-san,

    Thanks for your question.

    Daiki Noguchi said:
    Question: If I input PWM signals with different duty cycles to the PH and EN pins to create this waveform, will there be any issues with the IC?

    Generally no issues for the IC. When both PH and EN are 0 the outputs will be in brake current recirculation mode. Ensure the recirculation current does not exceed IOCP threshold, especially if the piezo if generating a voltage output. See below tables from the datasheet. You could consider the DRV8837 for PWM inputs to both IN1 and IN2, when they both are 0 the outputs will be in HiZ.

    You mentioned driving piezo element. While the device is not meant for this load, it could be used as long as absolute maximum ratings and the recommended operating conditions are in compliance in the application. Some piezo elements may have inductor in series which could lead to induced higher voltages. Ensure this does not happen. Thank you.

    Regards, Murugavel