LM25088: Bootstrap for buck DC/DC with LM25088

ACGUY

Guru 11170 points

Part Number: LM25088
Other Parts Discussed in Thread: LM5088, UCC5304

Hi all,

Please answer the question on following URL;

e2e.ti.com/.../923803

Regards,

ACGUY

over 5 years ago

0 Orlando Murray over 5 years ago

TI__Mastermind 22301 points

Hello,

I'm not sure the LM5088 can be used reliably for high voltage conversion like that. Let me check.

What's the TINA error you get?

-Orlando

0 ACGUY over 5 years ago in reply to Orlando Murray

Guru 11170 points

Hi,

Please run the added TINA file.

Regards,

ACGUY

0 ACGUY over 5 years ago in reply to Orlando Murray

Guru 11170 points

Hello Orlando,

Do you have any update?

Regards,

ACGUY

0 Orlando Murray over 5 years ago in reply to ACGUY

TI__Mastermind 22301 points

ACGUY,

I had to replace your MOSFET and diode because I did not have the libraries.

When I test with 100V components I first got a convergence issue with TINA.

Is that the issue you're seeing?

I can fix the convergence issue by going to "Analysis-> Set Analysis Parameters" and increasing the relative error tolerance like below.

Hope this helps,

-Orlando

0 ACGUY over 5 years ago in reply to Orlando Murray

Guru 11170 points

Hello Orlando,

Thank you for reply. However, I want to get really answer is for devices combination for DC/DC.
My idea is using an isolated gate driver as a boot strap for turn ON high side FET.

Could you discuss the circuit configuration with me? Or Could you introduce someone who can discuss?

Best regards,
ACGUY

0 Orlando Murray over 5 years ago in reply to ACGUY

TI__Mastermind 22301 points

AC Guy,

The feedback I received from the UCC5304 team was the bootstrap-capacitor may have trouble charging or keeping charged at startup with a non-synchronous topology. Their recommendation is to use a synchronous configuration as shown in the UCC5304 datasheet.

Perhaps you could pull switching node to GND to charge bootcap, but you risk shoot-though of the 400V if error or failure.

Another recommendation is to use a PFET with a non-synchronous solution like below.

https://e2e.ti.com/blogs_/b/powerhouse/archive/2017/08/25/crafty-idea-create-a-150v-non-synchronous-buck-solution-with-a-lower-vin-rated-controller

Hope this helps,

-Orlando

Power management

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LM25088: Bootstrap for buck DC/DC with LM25088