PMP10098: PMP10098 does not start with 20V AC input supply

Hi Anurag,

Where do you measure the voltage? How long are the cables between your lab supply and the board?

Hi,

Voltage across C9 is 28V DC.

How long are the cables between your lab supply and the board?

--> less than 1 meter.

Hi Anurag,

I had a look on the schematic and it looks like a kind of a constant current UVLO circuit. R2 sets the current to charge C16. R5/R13 defines the threshold voltage too turn on Q1. First I would recommend to increase R13 (for example 40kohm). Next, you could also increase the constant current by reducing R2 (for example 35kohm). After you did changes please check all voltage to be sure that you are not above the voltage ratings of the parts and controller. Just in case, you could add an additional zener diode too clamp the voltage. 

Thanks,

Florian