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DRV8711: The pre driver fault is often happend.

Kazuya Nakai59
Guru 20130 points
Part Number: DRV8711

 Hello guys,

 One of my customers is evaluating DRV8711 on their own board for their next products.

 In their evaluation, APDF (pre driver fault of A side) is often happened.

 So they have a few questions as the follwos. Could you please give me your reply?

 Q1. What is the condition APDF happens? (The customer and me couldn't find it in the device datasheet.)

 Q2. Is there any countermeasure by register setting, schematic or layout to reduce or eliminate the APDF?

 Your reply would be much appreciated.

 Best regards,

 Kazuya.

  • 0
    TI__Mastermind 37683 points

    Hi Kazuya,

    Q1:  What is the condition APDF happens? (The customer and me couldn't find it in the device datasheet.)

    A1: Section 7.3.11.2 of the datasheet explains the predriver fault conditions. The xPDF fault is triggered when the driver detects large current on the gate drive outputs. This will indicate some sort of short on the external FET. 

     Q2. Is there any countermeasure by register setting, schematic or layout to reduce or eliminate the APDF?

    A2: There is not much you can do with the register setting to help countermeasure the APDF fault. This fault is most likely the result of a short on the output FET (either by bad soldering/layout or faulty FET). I recommend the customer to check for any shorts on the output FETs of H-bridge A.  

     

  • 0 in reply to Pablo Armet
    Guru 20130 points

     Hi Pablo,

     Thank you very much for your reply.

     Could I ask you a few questions?

     The customer wanted to know the followings about PDF.

     Q3. What is the PDF detection current threshold?

            For example, is it 1.5 times of the setting current by IDRIVEN register value?

     Q4.  What is the PDF detection blanking time?

            Is PDF not detected when over-current duration is less than 100ns, for example?

     Q5. Is the PDF detection blanking time changed by IDRIVEN register value?

     Could you please give me your reply?

     Thank you again and best regards,

     Kazuya.

     

  • 0 in reply to Kazuya Nakai59
    TI__Mastermind 37683 points

    Hi Kazuya,

    Let me correct a statement I made in A1 from my previous reply. The PDF description in the datasheet can be misleading. The PDF fault is detecting sudden rise in the gate voltage NOT gate current. A similar question to yours was already answered in a previous e2e post. The reply to this post, https://e2e.ti.com/support/motor-drivers/f/38/t/749003?DRV8711-Predriver-Fault-XPDF-detection, answers Q3 and Q4. As for Q5, the blanking time should not be affected by different IDRIVE settings. 

  • 0 in reply to Pablo Armet
    Guru 20130 points

     Hi Pablo,

     Thank you very much for your reply.

     It is very helpful for the customer and me.

     Thank you again and best regards,

     Kazuya.