Pravin Gosavi
Member
Hello I have built an smps charger ( from 220 VAC) using UC3843B. I am supplying power to it from a different 12V battery temporarily because I am planning to supply it from an auxiliary winding. The transformer I got from an old smps inverter. I am running the oscillator at 64 KHZ freq at pin 4.
As I switch the circuit on, the output current I read is 5A where it is designed to output 10A. And the freq I measured at pin 4 is 120 KHZ and at the output pin it is 25 KHZ only. I think this makes the transformer to create a hissing sound. Also when I switch off the mains the output and oscillator freq becomes same 64KHZ which is the desired freq.
I also have added slope compensation circuit at pin 3 as in the datasheet. Sometimes I removed it but nothing changed. What I am missing? I am lost. Please help!
As I switch the circuit on, the output current I read is 5A where it is designed to output 10A. And the freq I measured at pin 4 is 120 KHZ and at the output pin it is 25 KHZ only. I think this makes the transformer to create a hissing sound. Also when I switch off the mains the output and oscillator freq becomes same 64KHZ which is the desired freq.
I also have added slope compensation circuit at pin 3 as in the datasheet. Sometimes I removed it but nothing changed. What I am missing? I am lost. Please help!