i have designed constant power supply using fairchild's fl7733a ic
Specifications
I/p voltage : 80 - 280V
Output Voltage : 7-40 v
Output current : 1.5Amps
When i connect full load led lights flicker when voltage is low(around 80 v ) but as soon as voltage is increased lights work properly. what must be the cause?
In their application note they have used the same value resistors. I increased the value of r1 to 1M it only delayed the startup time but flickering was still there. How we know if transformer is saturating or not. As the voltage reaches 130V the power supply is working fine.
I checked that yes the transformer was saturating so i made a new transformer and it is working fine but the new problem is it heats up to 80deg and also power factor reduces as the input voltage increases (Pf 0.94 for 230v). where to look for the problem According to datasheet capacitor at comi pin should be increased. I increased it from 2.2uf to 4.7uf but the power factor only increased by 0.01