LM5170: Boot-strapped function disabling, using an external gate driver.

Yuchuan Lu

Part Number: LM5170
Other Parts Discussed in Thread: LM5171

Tool/software:

Hi experts,

I'd like to use the LM5170 to drive the GaN FETs. Due to the PWM output voltage of LM5170 is 9~ 12 V, but the GaN FET needs 5 V.

Therefore I'm about to use the GaN driver LM1205 to transfer the voltages, and then the high-side boot-strapped function need to be disabled.

Just want to make sure whether my design is correct?

"HB1 and HB2 pins connected to the VCC/ SW1 and SW2 pins connected to the ground."

The schematic is shown below:

Hopefully to hear your feedback soon.

Best,

Lucien

6 months ago

0 Feng Ji 6 months ago

TI__Mastermind 22650 points

Hi Lucien,

You are right. Please also think about the boot strap UVLO at startup in buck mode. Please refer to below thread.

https://e2e.ti.com/support/power-management-group/power-management/f/power-management-forum/1000376/lm5170-q1-lm5170-q1-external-gate-driver-ucc27712dr

Best Regards,

Feng

0 Yuchuan Lu 6 months ago in reply to Feng Ji

Prodigy 20 points

Hi Feng,

Thanks for the reply and the reminder. In my application, the LM5170 will only operate in boost mode. I'll keep this issue in mind if one day I need to use it in Buck mode.

0 Feng Ji 6 months ago in reply to Yuchuan Lu

TI__Mastermind 22650 points

Hi Lucien,

Another suggestion is to think about LM5171 which is the successor of LM5170.

Best Regards,

Feng

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LM5170: Boot-strapped function disabling, using an external gate driver.