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DRV2625: Input and Regulator Capacitor Values

Michael_SD
Prodigy 90 points
Part Number: DRV2625

Hi, 

We are evaluating the DRV2625 using the DRV2625EVM-MINI evaluation board.  In our initial test setup, we were encountering under-voltage errors until we increased the capacitance for C(vdd) input capacitor, which resolved the problem.  Our question is:  would there be any cautions against increasing C(vdd) from 0.1uF (the recommended value) to 1.0 uF or 2.2uF (X5R ceramic capacitor)?  Also, we have the same question for C(reg) regulator capacitor:are there any cautions against increasing C(reg) from 0.1uF (recommended) to 1.0uF or 2.2uF?

Further details on our setup:

1)  UVLO threshold is set to 2.5V (lowest setting).

2)  Vdd is connected directly to the positive terminal of the battery.

3)  Battery is a small lithium polymer cell (30mAh).

4)  Motor type is ERM.

5)  Rated Voltage = 3.0V, Overdrive Clamp Voltage = 3.3V, Closed Loop Mode.

Thanks,
Michael

  • 0
    TI__Mastermind 20085 points
    Hi Michael,

    You can increase the decoupling capacitor value of the power supply, this shouldn't cause problems, but I would recommend you to use an X7R capacitor. I recommend you to leave the 0.1uF capacitor and add an extra 1uF or 2.2uF capacitor in case that you are going to design your system.
    Why do you want to increase the regulator capacitor?

    Best Regards
    José Luis Figueroa
    Audio Applications Engineer
  • 0 in reply to José Luis
    Prodigy 90 points

    Thanks for this reply and the recommendations!  Very helpful.

    Regarding your follow-up question, we don't have any particular need to increase the regulator capacitance.  We just noticed that the recommended capacitor values for both the C(vdd) and C(regulator) had changed from 1.0uF to 0.1uF between the 2605 and 2625 chips, and wanted to clarify.

    Thanks,
    Michael