UC2842: Doesn't work if based on webench result

Beginner

Part Number: UC2842

Hi Team,

My customer is evaluating UC2842AN w/ a transformer. All calculated is based on WEBENCH.

Based on WEBENCH result, we create a PCBA to test. However, it doesn't work. Please see attached - PCBA schematic and transformer report.

I suspect the transformer result is wrong. Please help to calculate the right value.

over 6 years ago

0 Beginner over 6 years ago

TI__Intellectual 2441 points

Flyback_Vin53-58.8_Vout56V.PDF

Transformer_spec_Vin53-58.8_Vo56V.PDF

0 John Griffin1 over 6 years ago in reply to Beginner

TI__Mastermind 34465 points

Hello BeMyself,

Do you have any test results from your pcb testing?

What happened when you applied power to your pcb ?

Regards

John

0 Beginner over 6 years ago in reply to John Griffin1

TI__Intellectual 2441 points

Target output is 56 volts, but measured result is lower w/ big gap.

0 Teng Feng over 6 years ago in reply to Beginner

TI__Genius 13660 points

Hello,

Sorry I haven't found any place wrong about schematic and transformer design, and where did you suspect is wrong in transformer design?

Please check VCC voltage value since VCC/Vout = 6 /19 according to transformer parameters. I'd like to look at whether PWM is working under the designed maximum duty? I'd like to look at the Isense pin, Comp pin voltage to see how is current sense comparator working? Please provide Isense pin, Comp pin and output pin waveform.

Regards,

Teng

0 Teng Feng over 6 years ago in reply to Teng Feng

TI__Genius 13660 points

Have any updated?

Since I haven’t heard back from you, I’m assuming you were able to resolve your issue. If not, just post a reply below (or create a new thread if the thread has locked due to time-out)

Thanks, Teng

Power management

Power management forum

UC2842: Doesn't work if based on webench result