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Original question:

DRV8215: Motor driver for a DC brushed motor

DRV8215: Over current protection is triggered instantly - even at 1% PWM on my 13 ohm motor

Can Caglar
Prodigy 10 points
Part Number: DRV8215

Tool/software:

Hi all,

I'm using the EVAL board (DRV8215EVM) for the DRV8215.

I follow the steps on the GUI and go to the Driver Control Panel.

These are the settings:

- Set H-Bridge control to PH/EN

- Fixed off-time current regulation

- 3.3V VREF

- 4A peak current

- 25kHz PWM

- No stall detection

and press Start Drive.

If my motor is not connected, I see the PWM duty ratio going from 0 to 100% as I move the slider, correctly.

However if I repeat the test with my motor connected, I immediately get an over current protection fault. It has happened with 2 different motors (both are the AJK-B2705, datasheet below)..

If I run my motors directly from a power supply at 6V and slowly reduce the voltage to test different motor speeds, I don't get this issue.

One interesting thing I noticed though is if the motor voltage is gradually raised on the power supply when the motor is connected then the motor doesn't work still. Not sure if this is related but I thought to share.

VSUP is 6V. 

Your help is appreciated!

Datasheet (pdf) for the motor:

AJK Standard_Product_Catalog_2024 (1).pdf

  • +1
    TI__Genius 12051 points

    Hello Can,

    Thanks for your question.

    I have assigned this ticket to the device expert. Please expect some delay in response due to US holidays.

    Thanks,

    Ibinu

  • +1
    TI__Mastermind 19860 points

    Hi Can,

    It's possible the IMODE setting is causing the OCP to trip. When IMODE is 01b the device performs current regulation only during the tINRUSH time when stall detection is enabled. I would suggest try changing the IMODE setting to 10b, this will enable current regulation at all times.

    Best,

    David

  • 0 in reply to David Medis
    Prodigy 10 points

    Thank you for your help.

    It looked like it worked (the pump started pumping and obeying the speed I programmed) but the OCP was still being triggered and I noticed the signal looked really weird on the scope (never reaching ground and having large peaks). Perhaps the issue is with the pump itself... I tried a different pump and the driver is working fine with no OCP issues (the same settings).