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Original question:

UCC27714: Can we power UCC27714 HB to HS with dedicated power supply?

LM5100A: HB pin usage for external power supply

Burak Efe Dirim
Prodigy 20 points
Part Number: LM5100A
Other Parts Discussed in Thread: UCC25800,

Hello, 

Can HB pin used as a floating high side power pin? That is, can I externally supply HB pin so that I do not need to use bootstrap configuration?

I need 100% duty cycle, thus I will use transformer driver for external high side supply (namely, UCC25800).

Thank you.

  • 0
    TI__Mastermind 23215 points

    Hello Burak,

    To achieve 100% duty cycle on the high side driver of the LM5100A you will need an external floating bias as you mention. The HB bias can be supplied by a bias supply such as the UCC25800 bias circuit.

    I would recommend that the power up sequence allow VDD to the LM5100A to rise before, or at the same time as the HB bias from the UCC25800. So that the bias power up sequence follows the same order as with a bootstrap bias supply.

    Regards,