UC3854A: Buck Converter using UC3854A

Ratish Ganve

Prodigy 50 points

Part Number: UC3854A
Other Parts Discussed in Thread: UC3854, UCC28180,

Hi,

In application note of UC3854, I read that this IC can also be used to configure Buck converter.

Please can anybody let me know how to configure it for the same & what modifications are required.

Regards,

Ratish Ganve

over 6 years ago

0 Wangxin Huang over 6 years ago

TI__Intellectual 1550 points

Hi Ratish,

Are you open to other parts? We have a reference design which uses UCC28180 for buck PFC. www.ti.com/.../TIDA-00652

0 Ratish Ganve over 6 years ago in reply to Wangxin Huang

Prodigy 50 points

Dear Wangxin,

First of all thanks for your quick response to my query.

But I would like to know about, configuring UC3854A for buck converter.

0 Wangxin Huang over 6 years ago in reply to Ratish Ganve

TI__Intellectual 1550 points

Ok. Do you need PFC? or just a regular buck.

0 Ratish Ganve over 6 years ago in reply to Wangxin Huang

Prodigy 50 points

Only regulator buck

0 Wangxin Huang over 6 years ago in reply to Ratish Ganve

TI__Intellectual 1550 points

Note that this part is developed for PFC application which generally has a very low bandwidth voltage loop. If you need a regular buck, I would recommend using buck PWM controllers rather than PFC controller.

0 Ratish Ganve over 6 years ago in reply to Wangxin Huang

Prodigy 50 points

Dear wangxin I just want to know how it can be configured as a buck controller by manipulating multiplier-squarer section, because I have seen some designs based on that.

If you have any idea regarding this then let me know.

0 Wangxin Huang over 6 years ago in reply to Ratish Ganve

TI__Intellectual 1550 points

Hi Ratish,

If you still insist using this boost PFC part for regular buck application, my advices would be:

1. Since you don't need PFC, then tie IAC and VRMS pins to constant voltage sources which effectively become a gain for the external voltage loop.

2. To drive a high-side buck switch, you will need add external high-side gate driver.

Regards,

Wangxin

0 Ratish Ganve over 6 years ago in reply to Wangxin Huang

Prodigy 50 points

Dear Wangxin,

Thanks

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UC3854A: Buck Converter using UC3854A