UCC28180: SS time

FRANK1

Part Number: UCC28180

Hi Sir,

For this device UCC28180D,

1)Can you tell me the soft start time of the IC?
Soft Start is programmed by the capacitance on this VCOMP pin.
also the same pin is used to provide the v-compensation,
Is there any chances of Voltage loop compensation being fast/ slow due to capacitor presence at pin for the both application

3) IC can be operated at 50/60Hz, We are operating it at 50Hz +/-3% variation .
so when i have frequency variation THD also varies ?
and how it will follow the AC line, as it does not have AC line sensing?

Thanks for your verification.

Regards,

over 4 years ago

0 Yunsheng Qu over 4 years ago

TI__Genius 9790 points

Hi, Frank

1. Besides capacitor (C2)on VCOMP pin, there is other Resistor + Capacitor (R1+C1) on VCOMP pin. C2 affect soft start time, R1+C1 mainly affect the loop response. So changing C2 affect soft start time a lot, but affect loop response a little. Since C2 is 1/100 of C1.

2. The THD variation is small at 50Hz +/-3% variation , since switching frequency is very higher then input AC frequency.

3. how input current follow the AC line? please refer to below thread.

https://e2e.ti.com/support/power-management/f/196/t/783252?UCC28180-How-the-IC-corrects-the-power-factor-without-Ac-line-Sense

BR,

Yunsheng

Power management

Power management forum

UCC28180: SS time