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DRV110EVM: hold current does not change

Matthew Harding
Prodigy 20 points
Part Number: DRV110EVM
Other Parts Discussed in Thread: DRV110

I'm using the DRV110EVM that I just received, and I am having a problem. There is a pot for R_HOLD, but no matter what position it is in, the hold current does not change, it stays at 140 mA. When I turn the pot for R_Peak, the peak current is adjusted appropriately.

I've measured the resistance at pin 4 on the part to ground and it does match the resistance measured at the test point next to the resistor. So the hardware does seem in good working condition as far as I can tell

I will note that I did turn the pot all the way up to 1M at one point, and afterwards I noticed the spec sheet says that resistance should be less than 333k.

Am I doing something wrong to adjust the hold current?

Thanks,
Matt

  • 0
    TI__Intellectual 805 points

    Hi Matt,

    Appreciate your interest in using DRV110 device in your design!

    Could you share additional details to your application of the EVM? (schematic, picture of setup, etc.)

    Sounds like pots are working fine, it could be that either hold or peak pin is connected to GND. Also, I assume you've reviewed datasheet on this already, but I highly recommend this section for diagnosing the problem.

    Thanks,
    Kevin

  • 0 in reply to Kevin Waddles
    Prodigy 20 points

    Here is an image of my setup. It is very minimal. I am powered from a benchtop supply, and have the scope clamp measuring coil current. I also have several scope traces at various Rhold and Rpeak combinations. It seems that there are only 2 possible outputs

    1) ~500mA peak, ~143mA hold

    or

    2) ~50mA peak, ~30mA hold

    I was doing this from the benchtop supply toggling power on that supply. I also tried keeping the supply on and using a switch over J9 to enable/disable. I also tried this powered from a 24V battery.

    Also, just after typing the above, I removed from the circuit the small blue/yellow wire pair to which the scope voltage probe was connected, and all works as expected now. Maybe the stripped back wires were touching the ESD mat and doing something unexpected?

  • 0 in reply to Matthew Harding
    TI__Intellectual 805 points

    Hi Matthew,

    Glad to hear you've solved the problem and EVM is working properly! Please don't hesitate to reach out if you have any additional questions regarding your setup.

    And yeah, looks like you've got a yellow wire splice to connect your scope probe it possibly could've caused the issue. Cheers nonetheless!

    Regards,

    Kevin