Gate Driver TPS28225 Calculating Bootstrap capacitor value.

Hieu Pham1

Other Parts Discussed in Thread: TPS28225

Are there any design guides from Texas Instrument for calculating the bootstrap capacitor value of the TPS28225 Gate Driver? There are design guides from other vendors/company with regarded to the bootstrap capacitor value, however they are using difference parameters.

My design specification:

Supply voltage: Vcc 5V, throughout the design

Gate driver: TPS28225

Switching MOSFET: IRFH8337PBF

P.S: At the moment I just used a random 150nF for my design, but this is risky.

Thanks

over 13 years ago

0 Vincenzo Pizzolante over 13 years ago

TI__Mastermind 25456 points

please refer to the attachment for details

Vincenzo

8372.AN-6076.pdf

0 Darnell Kemp over 12 years ago in reply to Vincenzo Pizzolante

Prodigy 50 points

This is a great article. I definitely have a few things to look at now. Thank you.

I was running my circuit at 250KHz PWM and to increase the resolution of the output I tried to reduce the PWM frequency by 10x to 25KHz. This caused by FETs to blow. I think the cause was a fully discharged bootstrap capacitor. I am using a 100nF CBOOT and a 2ohm RBOOT. My circuit is driving a pair of ST STD17NF03LT4 MOSFETs. (See Below)

I am hoping that probing CBOOT will show the problem and that increasing CBOOT will resolve the problem and allow us to get the improved output resolution we desire.

Darnell

0 Vincenzo Pizzolante over 12 years ago in reply to Darnell Kemp

TI__Mastermind 25456 points

I see,

but please also consider to check the spikes on SW node, since 30V FET have little margin Vs 24V application (whose spike could be in the ballpark of 1.5 x VDD = 36V)...

Vincenzo

Power management

Power management forum

Gate Driver TPS28225 Calculating Bootstrap capacitor value.