tny 268 going in the auto restart mode ?

Posted by: sandeep khatana on 12/26/2011

i am designing flyback converter input is 100-180v and output is 15v ,transformer polarity is ok optocoupler is KB815 PLZ HELP

Comments

please provide with schematic, since the optocoupler you are using is built in with the darlington transistor, i dont think it is necessary, and it may some times carry more current into the enable pin, please use pc817a

thanx for ur suggestion but i made some changes in the resistor of LED and it started working but my o/p is 15v i am getting it but when i am increaing the input voltage more thasn 130v it started decresing to 14.6 can u plz help why it is decresing?my i/p is fro 100-180v.

please provide the schematic

The schematic and PIExpert files will help.
In general if the supply goes into auto-restart there can only be 2 reasons for this:
1) The output is unintentionally shorted
2) The feedback loop is open - check for all connections, pin outs, cold solder joints.

i have design flyback converter input 80-180 dc and o/p 15 ,5 and -15v i have dee4sign center tap transformer for this can i see all o/p at a time plz help can i get o/p by regulating only 5v.