• State
  • Locked Locked
  • Replies 4 replies
  • Subscribers 63 subscribers
  • Views 1608 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

CSD17506 DRV8711 Application Mosfet Fault

Erhan Ergun
Intellectual 270 points
Other Parts Discussed in Thread: DRV8711, DRV8711EVM, CSD18504Q5A

Hello,

I designed a stepper motor driver card with drv8711 and csd17506. Design schematic values same as drv8711evm user's guide.

My company using this card in our products and at least 100 card worked great and there was no problem until new mosfets arrived. We get these mosfets from digikey and they look different. As i attached a photo of old and new ones you can see them.

The problem is, when i powered motor some of them burned suddenly some of them are working 1 sec some of them are working for 3 hours but all of them burning at last.

I thought about if there is a problem about components and ordered new ones from digikey again and same problem occurs. Resistance of drain and source of burned mosfets are nearly 0 Ohm.

Now i am thinking about if there is a version change in csd17506 but could not found any change only their visibility.

When i solder older ones they are working good, but new ones are getting damaged.

Whethere i am thinking about using gate resistor, the problem is both the problematic and workig well mosfets are csd17506. What would be the difference?

Should i try series gate resistor? In what value?

Note:What sould be the soldering degree of these mosfets?


Thank You

ou.

  • 0
    TI__Mastermind 18200 points
    Erhan, there was no change to the CSD17506Q5B.

    If you always bought through digikey, I don't think you need to worry about counterfeits. I can't get a good image of the two FETs however. Can you send another picture that shows the top marking a little more clearly?

    I don't think the DRV8711 would be the issue but what frequency are you switching at. I can talk to our applications team about recommending an external gate resistor.
  • 0 in reply to Brett Barr1
    Intellectual 270 points

    i thought about using gate resistor:

    Results=

    Gate resistor = 20 Ohm. Problem continued but worked a bit more seconds.

    Gate resistor= 240 Ohm. Problem solved but mosfets generated much heat and step motor is vibrating and working a bit noisy and vibrary. While motor driver enabled any driver keeps stepper motor at a position there is still noise.

    In what value should i use gate resistor?

    Do you have any other suggestions?

    Our mosfet's part numbers are:
    OLD:CSD1706 3113P JGD3R
    NEW: CSD17506 TI 34E MH01 E3


    I am driving my stepper motor in indexer mode and my indexer frequency between 10kHz and 1kHz.
    Thank You!

  • 0 in reply to Erhan Ergun
    Intellectual 270 points

    I am driving my motor with Vm=24V, my mosfets are 30V rated. Can it be a problem?

    Actually, when i did search always asking me the same question what is changed? They were working great but with new mosfets puf =).

    I will try with 50 ohm and 100 ohm. Also try other decay modes. Now i am using mixed decay. I also use higest value of dead time.

    One of my friend send this answer to me. Maybe this will show you something that i cant see.

    Here it is:

    It is the voltage shot through that destroyed the MOSFET. There was no change to the CSD17506Q5B. I was the EVM is using 60V MOSFET but the CSD17506 is 30V rated. This means your design is very marginal. The turn on speed of the high side MOSFET determines the Drain-Source voltage overshoot of the low side FET. If the high side FET is switched faster, the low side FET will suffered more. The turn on speed can be decreased by increasing the gate resistance and this will reduce the overshoot. However 240 Ohm is too much due to increased switching losses. I would not recommend any gate resistance larger than 20Ohm. The best solution would be using a bigger FET with 60V rated like CSD18534.

  • 0 in reply to Erhan Ergun
    TI__Mastermind 18200 points

    Erhan, 

    I agree that 30V on 24Vin is not very much margin, particularly if the transients are high. It is possible repetitive avalanching has led to overheating the FET. We have seen that occur with some customers. 

    You could try a 40V FET like the CSD18504Q5A before moving up to 60V. That might give you enough margin.