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DRV8312: DRV8312: search for DRV8312DDW damage reason(continue)

Y D
Prodigy 40 points
Part Number: DRV8312

 

Hello ,

I am a new user of E2E , I signed the previous post as “resolved” by mistake. I need the support still.

Also thank you for previous post reply.

 

The details are following :

- We are using PWM driver chip DRV8312DDW for about 2 years to control brushless DC motor.

- We used this chips for a relatively long time, but at the last time 3 chips in new cards were damaged.

- We are using CBC (cycle by cycle) current limit mode to control the brushless dc motor.

- The current limit is set to 4A, when according to data sheet the limit of the device is 3.5A continuous

(for the chip with the thermal pad on the bottom side).

- Some time ago we performed minor change in microcontroller SW version that delivers PWM to driver DRV8312.
- Before the SW version change, the motor driver DRV8312 worked well (device with code 62COZXTG4) .
- After the SW version change, running the motor driver under motor load caused to irreversible damage, i.e. previous SW version does work well also ...
- The problem occurred till now in three devices, we did not try to run the new SW with another devices from the same batch yet.
- The failure seems as "loss of driver strength", i.e. the motor is not able to deliver enough moment again the load, it stops soon after the motor start up.
- After replacement of the above devices with another ones (with code 38C34NTG4 ) - the design returned to work well again, but with old SW version, I don’t want to run them again with new SW version.
- The additional card with driver device signed 38C34NTG4 works well also with new version of SW.

I would like to ask:

·         Can overcurrent cause to the damage of the device in this case ?

·         May be there are some problems with devices batch (any errata, etc.) ? The device that we suspect as problematic is marked:

                        DRV8312

                        62COZXTG4


Best regards,
Y D

  • 0
    TI__Guru** 114905 points
    Hi Y D,

    Thank you for the follow up.

    What is different about the PWM delivery in the two SW versions?
    Have you examined the phase outputs using a scope during the "loss of driver strength" event? Can you see any difference?
  • 0 in reply to Rick Duncan
    Prodigy 40 points

    Hello Rick,

    Thank you for advice,   I tried but I did not find still any difference in PWM delivery...

    ...But I measured that both signals, Fault_n and OTW_n go to "0"  close after the motor control start in both (previous and a new) SW versions.  After power up, the  signals fault_n and otw_n are "1",  and thay are latched to "0" when reset_a_n , reset_b_n and reset_c_n go to "1" simultaneously for several milliseconds. PWM commands are "0" at that time.

    Additional detail:

    The new SW version works well after replacement of driver chip on the same board. May be some driver series are more durable/robust ?