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DRV8825: 40 ohms between V3P3OUT and GND

John Turner39
Prodigy 20 points
Part Number: DRV8825

I was buzzing out a new PCB in which the DRV8825 is the main IC. I noticed that I had a "short" between the V3P3OUT and gnd so I remove the bypass cap and still had this short of ~ 40ohms. I then tested pins 28 and 15 on an unsoldered chip and noticed the ground existed in both red to V3P3OUT and black to V3P3OUT. Should this be expected as its not in the datasheet ?

  • 0
    TI__Guru** 114905 points
    Hi John,

    We will investigate and reply by Wednesday. A reading of ~40 Ohms seems low.
  • 0 in reply to Rick Duncan
    TI__Guru** 114905 points

    Hi John,

    I used a Tektronix DMM4040 to measure the resistance on the DRV8825EVM.

    In one direction (HI to V3P3OUT / LO to GND), the reading is 4.4kOhms.

    In the other direction (HI to GND / LO to V3P3OUT) the reading is 3.5kOhms.

    What equipment are you using to measure the resistance?

  • 0 in reply to Rick Duncan
    Prodigy 20 points

    I used both a Milwaukee 2216-2 DMM as well as a Klein tools MM200. This was measured on two chips one soldered to a custom PCB both with bypass cap and without bypass cap and one on an insulating foam and all pins floating.  My custom PCB is mostly a breakout board with required filter caps and resistors, all other pins are left floating to their intended breakout pin I tried reading both way as you did as well and ended up with 50 ohms (HI to V3P3OUT / LO to GND) and 40 ohms (HI to GND / LO to V3P3OUT). Thinking I had nothing to risk I powered on the circuit anyways using a breadboard and current limited supply and the device turned on fine and V3P3OUT properly read 3.3v and now with no observable short.

  • 0 in reply to John Turner39
    TI__Guru** 114905 points
    Hi John,

    We are glad to hear the device powered up properly. Limiting the current is always a good idea.

    Please let us know if you require further assistance.