UCC28180: UCC28180 Application Question

Kuo John

Part Number: UCC28180
Other Parts Discussed in Thread: LM8365

Hi Team,

I according to reference design UCC28180 with LM8365 trigger OLP(open loop protection) to implement brown out function, but have some issue need you help!

Look waveform show result. LM8365 is right behavior, but UCC28180 GATE pin is fail behavior....(another verification Over voltage protection PWM can true turn off)

1. May I know UCC28180 has Hysteresis function for PWM ?

2. OLP and OVP disable PWM behavior is different, right?

3. Could you help provide suggestion? or you can help us to review schematic has error?

over 7 years ago

0 John Griffin1 over 7 years ago

TI__Mastermind 34465 points

Hello Kuo John,

TI recommends that the voltage on the ISENSE pin be limited to between 0 v and -1.1 v

On your schematic you have two 1N4148 diodes in series and this would limit ISENSE to about -1.4 v

Please check the operation with a single reverse diode.

In answer to your questions:

1 There is hysteresis on the OVP limit. PWM is disable if VSENSE reaches 109% of set value and re-enable at 102% of the set value.

2 Yes OLP and OVP are different.
OLP is 16.5% of the set value

3 Remove one of the 1N4148 diodes

Hope this helps

John

0 Kuo John over 7 years ago in reply to John Griffin1

Expert 1075 points

Hi Sir,

Thanks for your recommend. So Hysteresis just for OVP limit?

Regards,
Kuo

0 John Griffin1 over 7 years ago in reply to Kuo John

TI__Mastermind 34465 points

Hello Kuo,

Yes that is correct.

Regards

John

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UCC28180: UCC28180 Application Question