UC3854B: Gate output oscillation

Mason Noh

Expert 2490 points

Part Number: UC3854B

Hi TI,

Could you help to review the schematic as attachment?

Actually, we have a issue with the oscillation of gate output.

Some ICs on the same board have this oscillation and others do not have this problem.

over 5 years ago

0 Mason Noh over 5 years ago

Expert 2490 points

Do you think the IC that is observed to changing duty is judged to be defective?

0 Teng Feng over 5 years ago in reply to Mason Noh

TI__Genius 13660 points

Hi Mason,

I have contacted one of colleagues to answer your question. Thanks.

Regards,
Teng

0 Mason Noh over 5 years ago in reply to Teng Feng

Expert 2490 points

Hi Teng,

Could you check any update?

0 Bliss Zhou over 5 years ago

TI__Expert 3050 points

Hi Mason,

in order to understand you question, Could you please describe the IC apply conditions detail? and could you please show whole SCH.

thanks

0 Mason Noh over 5 years ago in reply to Bliss Zhou

Expert 2490 points

Hi Bliss,

It's whole schematic. I only supply 12V to VCC. There is no load. it's open loop.

This schematic is for

0 Mason Noh over 5 years ago in reply to Mason Noh

Expert 2490 points

This circuit is used to check the integrity of the IC.

0 Bliss Zhou over 5 years ago in reply to Mason Noh

TI__Expert 3050 points

Dear Mason,

I don't think that is ok which the Multiplier input PIN （IAC VRMS) is opened. according to the Datasheet the IMOUT = A*B/C, A from IAC and C from VRMS.

the impedance of these two PINs is uncertain if open this two PINs. Maybe,the output driver will be affected by the Noise.

Thanks

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UC3854B: Gate output oscillation