SN6501: floating bias supply

Hi Stefan,

Thanks for reaching out.

Stefan Lintner said:

will the proposed solution in below thread work for 3 half bridge drivers?

The proposed solution shows one half-bridge non-isolated gate driver and one SN6501 isolatoed / floating supply that powers the high-side gate driver. If you meant to ask if this can be repeated two more times to achieve solution for 3 half-bridges, then yes, you can do that. Each half-bridge operates independently and the respective SN6501 supply powers respective half-bridge. Hence, this is perfectly fine.

If you meant to ask if you can use one SN6501 solution for all three half-bridge high-side drivers then the answer is NO. Each high-side driver would require its own floating supply for it to work.

Stefan Lintner said:

Can you confirm that even with 100% duty cycle only one phase is active at a time and only one high side charge is needed?

Since SN6501 is providing the needed floating supply to high-side driver of UCC device, the solution doesn't depend on duty cycle of the gate driver network. Whether the duty cycle is 33% or 100%, the high-side gate driver is always powered and is always ready to turn-ON high-side MOSFET based on its input PWM signal.

Please note that MOSFET turn-ON depends on the LI and HI inputs to the gate driver and SN6501 has no play in controlling them. SN6501 only provide powers the gate driver and actual turn-ON times and duty cycle depend on the PWM signals at LI and HI of all half-bridges. Thanks.

Regards,
Koteshwar Rao