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DRV5032: DRV5032FA - 0.35V max output

David McDermott
Prodigy 20 points
Part Number: DRV5032


Tool/software:

I'm using a DRV5032FA (specifically a DRV5032FALPGM) and if I'm reading the datasheet right then it should be a push-pull output with a minimum high-level output of VCC-0.35V, however I consistently get an output of around 0.34-0.35V with VCCs from 3.3V to 5V. When I bring a magnet to the chip the output drops to 0V, as expected, and returns to 0.35V when the magnet is removed. This is in a simple setup with the power rails connected directly to power and ground and with the output connected to an oscilloscope. This behaviour is still observed after swapping out multiple different DRV5032FAs. Are all my chips broken? Am I doing something wrong or missing something?

  • 0
    TI__Mastermind 22400 points

    David,

    Thanks for reaching out on E2E.  Hopefully I'll be able to help to sort out what is happening here.  Is it possible to get a photo of the device markings on the individual unit under test?  

    Can you try to attach a weak pull-up on the OUT pin? Does the part function as we might expect with an open-drain output? 

    I assume your o-scope connection on OUT is referenced to GND and not VCC?

    Thanks,

    Scott

  • 0 in reply to Scott Bryson
    Prodigy 20 points

    This is a photo of one of the units I tested.

    With a 4.7kΩ pull-up resistor on the output the voltage was around 0.65V, and dropped to 0V when a magnet was brought to the chip. This was with a VCC of 5V, so not quite what would be expected with an open-drain output, but it is curious how the voltage increased. Also, with no pull-up resistor present there are regular spikes in the output of the chip with a period of about 100µs, which was also observed in the other units I tested and with a frequency that depended on the supply voltage. I had originally assumed that this was normal and an artifact of the internal sampling in the chip, but it was not present when the pull-up was used (or if it was its effect was greatly reduced).

    The oscilloscope probe is indeed referenced to ground and appears to be giving correct readings otherwise.

  • 0 in reply to David McDermott
    TI__Mastermind 22400 points

    David,

    This is curious.  I would have expected with the pull-up resistor to see the output run all the way up to your Vcc voltage.  Have you confirmed that your supply voltage is at the programmed level? The scope is DC coupled?  

    Thanks,

    Scott

  • 0 in reply to Scott Bryson
    Prodigy 20 points

    The supply voltage is indeed at the set level and scope is DC coupled. My suspicion is that the parts are defective, but these chips are unused I've tested a couple of the ones in this pack and they all exhibit this same behaviour, so either they're all defective or I'm just doing something wrong

  • +1 in reply to David McDermott
    TI__Mastermind 22400 points

    David,

    Do you have packing information for the units you received?  There should be a label with lot trace information.  We test devices leaving the factory, so I would expect that this behavior should have been detected. I can try to see if there was anything unusual with the batch of units you received. 

    Just to be sure, can you confirm your connection to the device pins?  The pin numbering is shown here:

    Where pin 1 (Vcc) is the left-most in the photo you sent.

  • 0 in reply to Scott Bryson
    Prodigy 20 points

    Uh... I might have accidentally swapped the ground and out pins -__- I guess that explains things lol. Thanks