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DRV201: no VCM current output at mid-high current setup.

Part Number: DRV201


I just run into some trouble using the DRV201 driver to drive a VCM for a research project. 

With the DRV201 evaluation board, it worked completely fine through the full range, However, once I switched to my own DRV201 adapter board, the driver fails at ~400 normalized VCM current. Beyond that current, when I update the current output, the driver will try to raise the current and rapidly drop to 0. No error is reported from the registry. 

I have tried quite a few different things to solve the problem (soldering technique, PCB spec and capacitor location), but the error kept happening. The board is extremely simple and almost identical to the evaluation board. I have not clue how to troubleshoot. At this point, any insight or suggestions will be helpful.

Some additional comments:
I just figured that above ~400 normalized current, the driver actually reset it self whenever I setup an output current. PWM/Freq settings are all reset to default. Without any VCM connected, the device reports a no connection error at any voltage output, which indicates no short connection.

  • Hi Yehe,

    Have you monitored the VBAT voltage, looking for droops that could reset the device?
    If you do not see anything, please compare all signals at the pins between the EVM and your adapter board. Please capture any differences and provide the scope captures.
  • Hi Rick,

    This was very inspiring, and the scope connection kinda solved my problem immediately.

    It was a very silly mistake. I misconnected the ground to a empty pin (the square pin on the EVM board) on the USB-I2C, and assumed that was the ground pin throughout the time, so the drive was not grounded all the time. It was working at low current output, so I did't think about the grounding problem at all.

    Anyway, thank you very much for helping out.