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DRV11873: DRV11873 has no output

Part Number: DRV11873

DRV11873 has no output in my application.

I made the following  confirmation and attempt

1.Test the impendence to GND of U/V/W of DRV11873

   OK PCBA: about 5MΩ   (with the Motor connectted to drv11873)

   NG PCBA:about 200Ω   (with the Motor connectted to drv11873)

2.Test the impendence to VCC of U/V/W of DRV11873

   OK PCBA: about 5MΩ   (with the Motor connectted to drv11873)

   NG PCBA:about 16KΩ   (with the Motor connectted to drv11873)

3.Test the voltage V5 of DRV11873 is OK 

4.Replace a new DRV11873 ,works normally

Attachment is my SCH.

Please help to analyze if there is something wrong with the design.

*Motor  parameter: Terminal Resistance:4.5Ω    Inductance:1.0mH   Kt:0.006Nm/A   12poles 3 phases, Brush less.

*I asked a related question before :

e2e.ti.com/.../3598722

  • Hi Chris,

    Thanks for posting your question in MD forum. Let me get back to you shortly.

    Regards,

    Vishnu

  • Hi Chris,

    I see V5 and external V3P3 connected to FG. Why is two power source used here?

    In your previous post, we identified that the PWM circuit is overloading V5. Did you try replacing your PWM circuit with the PWM signal generation circuit in the EVM?

    Is it just this one device that is not generating any output? 

    Regards,

    Vishnu

  • Hi Vishnu

    V5 is reserved ,the system is powered by 3.3V.

     PWM signal generation circuit is also powered by 3.3V, the PWM pin of DRV11873 is pull-up to 5V internal.So I'm worried that the 5V voltage will damage the CPU(Typical  3.3V ) of the system and add a triode isolation. If it is suspected that the over-current is caused by the transistor switch, I will cancel the transistor in the next version,use two resistors to divide the voltage. At present, there is no way to observe the mA level current waveform under the equipment conditions here(The values tested before are not accurate ).

    About 5 drv11873 failures occurred(Toltal number is 15).2 device V5 have no output,1device W/U/V has no output(The situation is as described above ),others have replaced the new IC because I didn't pay attention to miracles at the beginning.

    By the way, Does the impedance change of W/U/V  to ground mean that the MOS tube inside is burnt out? the root reason  is the logic control problem?

    Best Wish and Regards

    Chris

  • Hi Chris,

    Can you try using an external 5V power source and leave the V5 pin unloaded? 

    If the impedance across U/V/W to ground are low then there is a high chance that the MOSFETs are damaged. V5 is used as a power source to the logic control so any damage in V5 will impact MOSFET commutation logic.

    Regards,

    Vishnu

  • Hi Vishnu:

    Yes. But the PWM pin of DRV11873 has Pull-up to 5V internal.

    After the countermeasures, I will do more tests. If there are new situations, I will consult again .

    Best wish and regards!

    Chris

  • Hi Chris,

    I will close this for now. If you want a follow-up, please use the orange "Ask a related question" in the top right corner of the page.

    Regards,

    Vishnu

  • Hi Vishnu:

    OK ,thanks!

    Best wish and regards

    Chris