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DRV8302: The behavior when CP1 pin and CP2 pin are open.

Hisao Uchikoshi
Genius 13510 points
Part Number: DRV8302

Hi Experts,

Customer wants to know the behavior when CP1 pin and CP2 pin is open. When PVDD1 is 28.2V or higher, GVDD voltage begins to decrease then nFAULT pin is asserted. Is this expected behavior?

Customer is usually use DRV8302 with PVDD = 24V. In order to detect the soldering failure of CP1 pin and CP2, if this behavior is expected, they want to add the test condition like that applying 30V at PVDD and see if nFAULT pin is asserted or not.

Regards,

Uchikoshi

  • 0
    TI__Intellectual 2345 points

    Hey Uchikoshi,

    I'm not familiar with the internal circuitry of the charge pump on this device and so I can not tell you if this expected behavior.

    I can reach out to our design team and have them look in to it. Please give me a couple of days and I'll get back to you.

    Regards,

    Paul

  • 0 in reply to Paul Parrot
    TI__Genius 13510 points

    Hi Paul,

    Are there any update?

    Regards,

    Uchikoshi

  • 0 in reply to Hisao Uchikoshi
    TI__Intellectual 2345 points

    Hey Uchikoshi,

    I have reached out to our design team and am waiting for their feedback.

    I will follow up with them and try to have an update for you by tomorrow.

    Regards,

    Paul

  • 0 in reply to Paul Parrot
    TI__Intellectual 2345 points

    Hey Uchikoshi,

    For this device to function properly the cap between CP1 and CP2 must be populated. Without this cap populated the charge pump will be unable to supply the extra voltage needed for the high-side gate to turn on and stay on. This means even with the 24V that your customer normally uses, without the charge pump cap populated, the device should flag either a GVDD undervoltage or Vds overcurrent fault if they are trying to run the motor.

    You mentioned they only see the flag when PVDD1 is greater than 28.2V. Are they attempting to drive any outputs during this test?

    Any easy way to test if the charge pump is working is to try and run the motor by turning on any of the high-side gates. If the charge pump is unable to supply the required voltage, the high-side gate should be unable to turn on (or even if it does it will not be able to stay on). In either case, you should see a GVDD undervoltage or a Vds overcurrent fault get set.

    Regards,

    Paul

  • 0 in reply to Paul Parrot
    TI__Intellectual 2345 points

    Hey Uchikoshi,

    The design team came back with some more interesting information relating to the chargepump on this specific device. It seems the chargepump on this device is capable of supporting a load with the cap unpopulated when PVDD1 is between ~11 and ~28V. I was able to run a few tests and confirm this behavior this afternoon.

    My tests showed that if PVDD1 exceeds 28.2V a fault will be flagged. Similarly, a fault will be flagged if PVDD1 drops below 10.7V. So to correct my previous statement, your customer should be able to test for soldering issues on CP1 and CP2 by checking for a fault when PVDD1 is less than 10.7V or greater than 28.2V.

    Regards,

    Paul

  • 0 in reply to Paul Parrot
    TI__Genius 13510 points

    Hi Paul,

    Thank you so much for bringing us the update.

    Regards,

    Uchikoshi