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DRV8300: current limiting resistor of BST-pin

Yasushi Fujiwara
Genius 12725 points
Part Number: DRV8300

Hello Experts,

My customer has question about BST-pin for DRV8300D. According to datasheet, the recommended cap value for bootstrap is 1uF maximum. At this condition, limiting resistor (between BSTx and capacitor) does not need, correct?

If customer would like to design DRV8300D by a following condition, does it need a current limiting resistor? If so, please tell a recommended value and a power rating.
[conditions]
- VGVDD=12V
- bootstrap cap=2.2uF
- switching frequency: 32KHz or 64KHz

Best Regards,
Fujiwara

  • +1
    TI__Mastermind 23045 points

    Hello Yasushi-san,

    Thank you for your question, yes that is correct if using a 1uF capacitor then there is no need for a current limiting resistor, the datasheet indicates that if using a CBSTx greater than 1uF the current going through DBOOT needs to be limited.

    Has the customer done the calculations on section 9.2.2 of the datasheet? This will give you the minimum value needed for CBSTx, I am just curious where the value of 2.2uF was obtained from and if it is necessary to use. Looking forward to your response.

    Best,

    Isaac

  • 0 in reply to Isaac Lara
    TI__Genius 12725 points

    Hello Isaac-san,

    Customer calculated a boot-cap value based on equation (1),(2) and (3) in datasheet and the result is less than 1uF. Customer will use less than 1uF boot-cap. Thank you for the suggestion.

    Best Regards,
    Fujiwara

  • 0 in reply to Yasushi Fujiwara
    TI__Mastermind 21805 points

    Thanks Fujiwara-san!

    I will close this thread.

    Thanks,

    Matt