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DRV8353: OC Issue

Brian Wang0928
Genius 14150 points
Part Number: DRV8353

Tool/software:

Team

Customer found the device is failure when doing the pre-short circuit by short wiring between V-W and U-V phases. 

So far, there were 4 devices failure(NO SOA/SOB/SOC output) after doing phase to phase short-circuit on customer's board.

- With A-B-A swap, the system is normally operation with new device.

- Doing the impedance measurement between SOx to GND. no matter NG or Good Part it's about 270K Ohm.

Register setting: 

OCP_MODE: 01b (Automatic Retry)

tOCP_DEG:10b

OCP_ACT: 01b

VSEN_OCP:01b

After doing short-circuit test, below registers are triggered and it indicates FAULT signal.  

CH1: Vgs_W, CH2: Vds_W, CH3: VM, CH4: IV to IW short current

After this waveform, SOA/B/C has no output present. 

Schematic:

MOSFET p/n: MDLT080N017RM

4861.Circuit.pdf

Regards

Brian

  • 0
    TI__Genius 14150 points

    Team, could you please help with this issue as it's urgency now in customer site!  and in parallel, customer will send 2 failure units for decap and FAR. Very thanks. 

  • 0 in reply to Brian Wang0928
    TI__Expert 4785 points

    Hi Brian,

    Please check with customer to confirm:

    1. What is clear behavior of Good device? nFault appears, but no damage on SOx? please confirm

    2. Has customer checked any other pins for potential damage? Since you mention SOx pin still have 270k ohm on NG parts?

    3. Thank you for providing units for FAR. This will likely be necessary in solving the issue if there is internal damage.

    Thank you,

    Joseph

  • 0 in reply to Joseph Ferri
    TI__Genius 14150 points
    1. What is clear behavior of Good device? nFault appears, but no damage on SOx? please confirm!

    [4/22]For Good device, when did a short test, the nFault activate and fault register changes status. After power on reset, the part works normally.

     

    1. For GOOD part, does RD see fault, but SOx output is till operational? [4/22]When see fault on Good part after short-test, the device is in shuntdown. After POR, the device is still operational.

     

    1. RD see same fault on Good and NG part, but for NG part there’s no SOx output is that correct? [4/22] Yes! There’s no output voltage on SOx. It seems 0V.When RD sees fault, part is damaged after? Even after clear fault, device will have no SOx output?[4/22] After POR, the NG part still has no SOx output.

     4. Has customer checked any other pins for potential damage? Since you mention SOx pin still have 270k ohm on NG parts?

    [4/22]Besides NG part of the DRV8353, there is no any others damaged, and no damaged/hot spot around the part is observed. After A-B-A swap, the system can be operational with new part.

  • 0 in reply to Brian Wang0928
    TI__Expert 4785 points

    Hi Brian,

    Here are some things I have found that the customer can try.

    1. Has customer tried using different Rsense values? For example have they tried 0.1m ohm resister for sense resistor. Currently, schematic shows 0.2m resistor for current sense. (0.0002ohm*550A) = 0.11V, which can get close to max of Vcom, common mode input range.

    2. Try to lower the VDS_LVL threshold through SPI. Try different lower register values for VDS_LVL. My thought is that if you can catch the fault earlier this way then damage can be prevented by using this lower threshold.