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DRV8701E burned after power on with motor connected.

Other Parts Discussed in Thread: DRV8701

Hello,

We recently asked a company to develop a motor driver for us.We got the board and when we connect this this the DRV8701E blow up.

(yes blow up, only power on,not running motor  just put power on the card with motor connected)


the company is saying that the problem is our machine,(potential voltage difference). somehow I think this is not correct. (other cards do not blow up)

also if I would turn the motor by hand it would create a voltage, that would go back to the driver. so this would also damage it ?

I think they didn't design it correctly. but I would like to know a bit more :


1. if there was incoming voltage from the motor to the driver. the H-bridge would stop this ? if not how much voltage can the DRV8701E withstand ?

2. looking at the schematic drawing, do you guys see anything obviously wrong in the design ?

3. to prevent this from happening what protection is necessary ? does such protection shows in the application notes ??

hope you guys can help me a bit .

many thanks

Peter

 

  • Hi Peter,

    The schematic appears to be good. Our expert will also be contacted for his opinion.

    What is the V_MOTOR voltage? When the card was powered up, what power supply was used (battery, power supply)? Is the control pin gnd the same as the DRV8701 and FET gnd?

    Is it possible the device was incorrectly mounted? It is difficult to determine the pin 1 location in the picture provided.
    Could there have been a solder bridge somewhere that shorted a couple of pins?
    Do you have a second board? If so, after a visual inspection can you power the board with no motor, using a 100mA current limit and raising VM slowly?
    Can you provide the layout?

    The DRV8701 does not stop incoming voltages from the motor. As the voltage is generated, the body diodes of the FETs are turned on to clamp the voltage to VM+diode or GND-diode. The DRV8701 is designed to withstand up to the absolute maximum voltages listed in the datasheet.
  • Hello Rick,

    thanks for your quick reply,

    V_MOTOR voltage is 37V, the card is powered by a power supply (AC 48Volt converted to DC)

    the GND of FET and Control pin is the same.

    We actually have more then 10 boards that are broken the same way (after power on the boards ~3 - 5 sec the DRV8701 burned.

    please find some more data attached.

    Rick Duncan said:


    The DRV8701 does not stop incoming voltages from the motor. As the voltage is generated, the body diodes of the FETs are turned on to clamp the voltage to VM+diode or GND-diode. The DRV8701is designed to withstand up to the absolute maximum voltages listed in the datasheet.

    so this maximum voltage is 45volt. above this the DRV8701 will be damaged.

    Like I said I just want to have a second opinion. as i'm not very technical at component base.

    for the layout, I can give you . but the suppliers name is printed on this, and I don't want to create a bad name for him.

    and I don't have the tools to take the name out.

     

  • Hi Peter,

    The DRV8701 can be damaged if VM exceeds 47V.

    Can you describe what is happening in the first 2 to 3 seconds after power up?
    You said the motor is not running. What is the state of each input and output?

    Can you / have you tried powering a board up slowly with a current limited supply?

    I appreciate your desire to keep the supplier name out of this. I will send instructions on how to send the files soon.
  • Hi Rick,

    We power on the transformer (48VAc),( on the board it is converted to 37 volt DC.)
    Then everything seems normal, meaning motor is not running and the board shows Green light(this means the self check function of board is ok) and then the Ic burned, either the fuse breaks earlier, or the ic breaks earlier.

    Basically we didn't try to do anything yet.

    Peter