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SN6505B: Does this pushpull driver need a snubber to be added?

Andrew Massey
Prodigy 120 points

Part Number: SN6505B

Hi,

Would you agree that the SN6505 application circuits shown in its datasheet would also need a Diode/TVS to be added to snub out the leakage inductance induced overvoltage?

The interneal FETs are only 16v rated, so would you agree, an 8V2 TVS/Zener and a dioe should be connected from Vin to the drain of each internal transisfor?

  • 0
    Prodigy 120 points

    Also, supposing i want to add a hi side drive supply to a 400Vin full bridge converter. Would i be able to do that using an SN6505 based converter?

    And would you agree those wuerth transformers in the SN6505  datasheet may have too much interwinding capacitance for use in such a case?

  • 0 in reply to Andrew Massey
    TI__Mastermind 25225 points

    Hello Andrew,

    Please note that today was a holiday for our US based teams, our experts will take a look at this tomorrow and get back to you.

    Best,
    Michael

  • 0 in reply to Andrew Massey
    TI__Guru 57175 points

    Hi Andrew,

    Thanks for reaching out, please see my inputs below.

    Andrew Massey said:
    Would you agree that the SN6505 application circuits shown in its datasheet would also need a Diode/TVS to be added to snub out the leakage inductance induced overvoltage?

    I am assuming that you are asking if we need snubber circuit for device operation. Push-pull doesn't require any snubber circuit for operation and so is the case with SN6505. One can have RC snubber on D1/D2 pins or at the diodes on the secondary to suppress any ringing to improve EMI performance, I believe that generally is not needed.

    Andrew Massey said:
    The interneal FETs are only 16v rated, so would you agree, an 8V2 TVS/Zener and a dioe should be connected from Vin to the drain of each internal transisfor?

    Since the max input supply is 5.5V and since reflected voltage from output will also be stepped down, we don't see it being a concern on D1/D2 pins. We haven't not have issues in this regard.

    Andrew Massey said:
    Also, supposing i want to add a hi side drive supply to a 400Vin full bridge converter. Would i be able to do that using an SN6505 based converter?

    SN6505 based power supply can be used to supply high-side driver, please refer to the below example reference design that uses SN6505B for generating supply for all the 6 gate drivers for a 3-phase inverter.

    https://www.ti.com/tool/TIDA-00446

    Andrew Massey said:
    And would you agree those wuerth transformers in the SN6505  datasheet may have too much interwinding capacitance for use in such a case?

    I see that some of the transformers have an inter-winding capacitance of about 15pF. I am not sure if this is a concern for your application but we haven't heard from any customers this being problem to them.

    Let me know if you have any further questions, thanks.


    Regards,
    Koteshwar Rao