BQ25756: gate driver capability for high-power designs

Sam Ting

Part Number: BQ25756
Other Parts Discussed in Thread: BQ25820

Tool/software:

Team,

My customer is evaluating a high-output-power design (500 W) with the BQ25756. Engineers need to know if this device's gate-driver capability is sufficient for two high-side and two low-side MOSFETs. Could you please provide your comments? Thanks!

Design specs:
Power source: 24V
System + battery charging: 12V/500W
MOSFET PN: NTMFS5C628NL

Regards,
Sam Ting

2 months ago

0 Michael Bradbourne 2 months ago

TI__Expert 6355 points

Hi Sam,

500 W at 12 V is a current 41.67 A. This device looks to be rated at 28 A when mounted to a PCB. By two high-side and two low-side, do you mean 2 attached to each gate driver for a total of 8 MOSFETs in the design?

Best,
Michael

0 Sam Ting 2 months ago in reply to Michael Bradbourne

TI__Expert 3590 points

Hi Michael,

Please refer to the simplified schematic below. During DPM, the battery discharges to support the system load. Or do we have other solutions? They could be more suitable. Thanks!

Regards,
Sam Ting

+1 Michael Bradbourne 2 months ago in reply to Sam Ting

TI__Expert 6355 points

Hi Sam,

I think that this MOSFET selection should be fine. What is the switching frequency of this operation?

BTW, if you are going to short and open the MOSFETs on the output side of the inductor, I recommend using the BQ25820. This is a buck-only device that is pin-to-pin and register-to-register with the BQ25756.

Best,
Michael

0 Sam Ting 2 months ago in reply to Michael Bradbourne

TI__Expert 3590 points

Michael,

Thanks for your support!

Regards,
Sam Ting

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BQ25756: gate driver capability for high-power designs