Hello there,
I was going through the difference between UCC28810 and UCC28811 in the datasheet and found this.
May I know how higher UNLO turn-on threshold will help in smaller VDD capacitance and quick startup. Should it be not reverse or am I missing something?
Thanks!
Hi Nilesh,
To startup, all of the charge that goes to the gate will be coming off of the capacitor labeled Cs below:
With the higher UVLO you can use a slightly smaller capacitor because there will be enough margin to turn on the FET without VDD falling below the turn-off threshold which could be 10V.
Does this help to answer your question?
Hi Nilesh,
As long as you meet the UVLO requirements and have enough Cs to support startup, both will run with a 15-16V aux supply. The UVLO turn-off threshold is the same for both:
So to be clear, for turn-on the high-voltage startup must charge Cs to rise above the UVLO threshold, Once running, power is supplied via the aux winding. The device will remain operational until VDD falls below the ULVO turn-off threshold.
Does this make sense?
