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DRV8353: nFAULT LED lights up - DRV8353Rs-EVM Board

Part Number: DRV8353

Hi,

I would like to test the DRV8353Rs-EVM-Board with ISO-F28027F. This board is connected with BLDC motor and is supplied with 60VDC / max. 3A. This Gate driver board worked very well with TI program DRV8353Rx 1.0.0. The parameters of motor are identified and the motor could run with speed control.

After that I wanted to change operating mode from “split rail” to “single rain” by replaced of resistor R19 and R18. Then I changed the LDO output from 12V (standard) to 5V by changing of resistor R29 (from 2,61k to 10k).

Now the motor can no longer be identified and controlled. The nFAULT-LED is lighting up. Based on the register report on program DRV8353Rx 1.0.0, I suspect the error is due to VCP- Charge pump under voltage. You can see these pictures of register report below.

I have also measured the voltages VM, Vcp, Vgls and Dvdd. Only the charge pump voltage Vcp is noticeable. This is 42,2V (VM+2V), although it’s supposed to be VM+10,5V as a recommendation.

I want to ask you, if I’ve done something wrong? Can you give me some helps to solve this problem?

Any helps will be appreciate!

Thanks for your attention,

Hoang

  • Hoang,

    I don't know the answer yet. Would you do only one change at a time? And then, check the test result.

  • Hi Wang,
    I made both changes at a time, then came the error. I've tried to make it look like the original circuit again. But it doesn't happend anymore. This driver-chip is always warmer.
    I can't get the motor running, that's why i've cancelled the measurement.

    Best Regards,

    Hoang
  • Hoang,

    " I've tried to make it look like the original circuit again. But it doesn't happend anymore. "

    Do you mean your board doesn't work or the issue is gone?

    Hector also gave some comments for this debugging:

    "does it work after you configured the PCB to be in split rail mode?

    what value you measured across VGLS and if you measures those supply voltages when the fault is triggered (scope captures)?

    Other useful measurements to know are VBUCK and V3P3OUT.

    I see the C29 VGLS capacitor is close to the C30 capacitor and I worry a short might be occurring." Please double check it.

  • Dear Wang,

    Sorry for my late answer. 

    - "Do you mean your board doesn't work or the issue is gone?"

    I think the board is still working well. The measurements show in standard configuration these follow voltages:

    Vin=Vdrain=40,5V,

    Vm (Testpoint16) = Vbuck =12,35 V,

    V_cp (Testpoint 15)=42,4V,a

    DVDD(pin40)=5,32V,

    CPH:

    CPL:

    VCC (pin44) = 7,28V

    Vgls = about 3,1V

    And signals from GLA=3V, GLB=GLC=0, GHA=0, GHB=GHC=34,1V

    But I have no idea to start the motor through this board. I have used only the program DRV8353 v001. Unfortunately, the motor cannot be identified and of course the nFAULT-LED lights up.

    I hope, you have some idea to help me to solve this problem.

    Thank you, Wang.

  • Hoang,

    I would think the board has some issue because:
    Vin=Vdrain=40,5V,
    V_cp (Testpoint 15)=42,4V

    Vcp should be 10.5V higher than Vdrain (see datasheet page 12 spec table).

    Can you check the external high side FET's gate resistance?
  • Wang,

    I agree with you, that the voltage of Vcp is too small. But I have no idea why is it.

    I have tested this board without motor and the gate signals to GND show

    GLA=3V, GLB=GLC=0,

    GHA=0, GHB=GHC=34,1V

    I think the Mosfets are still OK, because all internal inverse diode are also gut (I have measured therefor with multimeter) .

    The drain source voltages Uds of Highside Mosfet are:

    Uds_A=39,9V

    Uds_B=37,7V

    Uds_C=6,2V

    And the voltages between GHx and SHx are also 0V (i have measured with multimeter)

    Maybe you have some idea, where the error is.

    Best regards,

    Hoang

  • Hoang,

    If you have verified the FET's gate resistance was normal, I would think the DRV part is damaged somehow. Would you replace the IC and retry it?
    Right now, we are still struggling what changes have you made from the original EVM. If you have second EVM as reference, it may speed up the debugging process.
  • Hi Wang,

    I also think, there is a internal problem in this IC. I would like to replace and retry it. I have ordered also 5 exemplars of IC “DRV8353”. It would be nice if i had the second EVM-Board, but I have only one.

    Can I have the second EVM in your opinion?

    More Infos for clearer analysis these changes were:

    1. Single to Split Configuration ( R18 connected, R19 disconnected)
    2. Vbuck from 12V to 5V (R29_ 2.61k -> 10k)
    3. VM raised up to 60 V
    4. Then fails.

    Best regard,

    Hoang

    Wang5577 said:
    Hoang,

    If you have verified the FET's gate resistance was normal, I would think the DRV part is damaged somehow. Would you replace the IC and retry it?
    Right now, we are still struggling what changes have you made from the original EVM. If you have second EVM as reference, it may speed up the debugging process.

  • Hoang,

    VM operation range is from 9~75V. After you change Vbuck from 12V to 5V and connect it to VM. The VM voltage is below 9V.
    Would you keep Vbuck at 12V?
  • Wang,

    For the Split Configuration:

    At first i changed the supply configuration (R18), VM is also equal to Vdrain=60V. And then I have configured vbuck to 5V. I think these two voltages are separate.

    i have measured there: Vbuck=5,3V and Vm=60,1V

    For Restore to original circuit:

    At first i changed vbuck from 5V to 12V, then connected R19 again. The measurements are: Vbuck=12,1V and Vm=12,1V

  • Hoang,

    "Single to Split Configuration ( R18 connected, R19 disconnected)"
    On the EVM user's guide, "For single rail configuration, connect R18 and disconnect R19." So, you modified the board from split to single configuration. In this case, Vbuck could be 5.3V.

    Anyway, we have to have a working EVM to discuss the part behave.
  • Hoang,
    Let me close this post. After you replace IC and modify the board back or get a new working board, we can do one change at one time and check the board operation.
    If you have the failure again, you can start a new post. At that time, we know what specific change causes the issue and only focus on that change.
  • Hi Wang,

    Since last post i have changed this IC "DRV8353RS" with the new one. BUT we have again bad message.

    With the same program DRV8353Rx 1.0.0 from TI, I want to run my motor. From Start were everything’s Ok, this board try to identify the motor parameters. Then the fault “overcurrent ion phase A” came. I thing this IC died again.

    Do you have any idea to solve this problem ?

    best regard,

    Hoang

  • Hoang,

    If the IC is new, I have to say the surrounding components may be damaged before you replace the IC. Sorry, I cannot directly point out which component was already damaged. Would you get a new EVM to start your test?
  • Hi Wang,

    I have already orded the new EVM Board and i'm waiting for the delivery. 

    I hope everything will be Ok with the new EVM. 

    For sure, could you please  send me the lastes documents for user's guide ?

    Should i start to test the gate driver with the Program from TI : "DRV8353R 1.0.0" or should i start with code composer with project5b ?

    Thanks for your support !

    Hoang

  • Hoang,

    Please use DRV8353RS/H-EVM GUI (www.ti.com/.../slvc737).
    The GUI user's guide can also be found in: www.ti.com/.../slvu791
    When you have the new EVM, please only change one thing at one time. So, we can easily find out the issue. For next EVM debugging, would you start a new thread? This one is too long and the new EVM debugging should face different issue than this one if there is an issue.