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DRV8350H-EVM: I have referenced the DRV8350 EVM and have a new design , now it indicated my HALL SENSOR error.

Part Number: DRV8350H-EVM
Other Parts Discussed in Thread: DRV8350, DRV5021, MSP430F5529, DRV835X

I have referenced the DRV8350 EVM and have a new design ,  now it indicated my HALL SENSOR error.  I have used the oscilloscope and measured the Connection end of Hall sensor and PCB board.It just like the picture below.HALL A  high level is 10mv,low level is almost 0v, HALL B high level is 120mv, low level is 20 mv, HALL C is same with HALL B.

It indicated that HALL A not worked well. So I have changed the HALL A and HALL B , but it stil indicated that the signal on the end of the hall A connection is wrong. So the motor hall fault was eliminated, and it was determined that it should be PCB problem.

The below picture is my PCB design.

But HALL B and HALL C connection are same like that ,Why HALL A was error? what's the problem?

  • Hello user6190682,

    +100mV for a single ended hall sensor is far too low. It looks like you didn't use an external pull up on the output of each of the hall signals. The DRV8350 expects 3.3V - 5V logic for the INx pins when using it in 1x PWM mode, or what ever the GPIO voltage logic is needed if the MCU is going to be receiving the hall sensor signals.

    As an example, see how the DRV5021 has a pull up on the output of the sensor that is the same logic as the controller?

    If you already have a pull up then you need to see if there's a problem with the voltage source powering the pull up voltage (VCC in the picture above).



  • Hello cole,

    Thank you for your reply. I still have a external pull up on the output of each HALL signal. Picture below is a segment os my schematic contains HALL SIGNALS

    Just now I have measured the voltage source of VCC with board all powered up. The VCC voltage is 3.26v. It is correct.but signal end is 100mv and 10mv.

    and I still want to say is that I set up the pull up inside the chip like below.

  • Hello Cole, 

    May you have a good day, today I have thinked a lot , I mean  if using 6×PWM, INx pin from MSP430F5529 as the output,if I have solderd the unpopulated 0 ohm resistors just like the picture above . The HALL Signal and the  INx signal will conflict,  they are all output signals. So is it signal from INx makes the signal from HALL SENSOR unnormal? But  I have checked the drv8350x  user guide , it indicated that  if using sensored firmware on MSP430F5529 , it needs to solder the unpopupated 0 ohm resistors just like the picture below  which is Screenshot from the file DRV8350x-EVM User’s Guide.pdf on the page 23.  I am confused now. So is it INx caused the HALL SENSOR  SIGNAL  Unnormal?  And is it necessary to solder the 0 ohm resistors  if using 6×pwm sensored firmware ?

  • Hello user6190682,

    Hall Sensor:

    The hall configuration above is only compatible with PWM 1x mode and no other mode. This means, I would expect the mode pin to be Hi-Z (>500 k ohm to AGND) and R4, R6, and R7 to be populated.

    So make sure PWM 1x is enabled, then make sure there is no damage on the INx pins (review the schematic, disconnect motor and hall sensors, use a DMM to measure resistance or impedance between the pins to GND, and make sure they are not in "<10 ohms"). If everything is good, then there is nothing wrong with DRV835x and you have to debug the source of the problem without my help (as the DRV835x is not the problem).

    My tips are to double check P1 and make sure the voltage is present, check the impedance of the hall sensors and make sure there is no damage, etc. Try to isolate where the problem may be by figuring out what is working as intended and then ruling that out.

    More info on PWM 6x mode:

    You're correct, if you wanted to use PWM 6x mode the motor commutation algorithm integrated on the DRV835x would have replaced by creating FW for the MSP (this is what we mean by sensored FW). This means, the Hall sensors no longer connect to the DRV835x but instead be connected to the MSP and the MSP would decide when to commutate (by switching the INx signals that no longer have the hall sensors connected depending on the hall sensor inputs). 



  • Hello Cole,

    Thank you for your explanation with patience, as I take away the HALL SENSOR 0 ohm  resistors , Now it works well  .so I want to point out there are something wrong with the file of DRV8350x_EVM  USER GUIDE. It said  if use the sensored firmware user should solder the unpopulated HALL SENSOR resistors.

    Thank you so much Cole.

    May you have a good day.

  • Hello user6190682,

    Thanks for the response. Glad it worked. We'll look into clarifying the user guide.

    Please click the "This resolved my issue" on your reply so other people with this issue can find this answer more easily.