Hello
I designed a forward converter based on UC3843. I recently encountered an issue in designing output overcurrent and short circuit protection circuits.
I thought of two overcurrent protection circuits,
one that puts the input current through the sampling resistor to the Isence pin of the UC3843 at the primary. When overcurrent, the UC3843 enters the hiccup mode and consumes less power. However, in this way, the capacity with capacitive load at startup is only 1000uF, which can't reach the 10000uF required by customers.
I also used the second method, which is to sample the output current. When overcurrent, switch the control loop from the voltage loop to the current loop, so that it can enter the constant current control mode. The capacitive load of 10000uF can work, but because It is a constant current mode, the current in the circuit is large, and the short circuit loss is as high as 40W, which is also undesirable for customers.
Excuse me, what are the commonly used short circuit protection circuits? Do you have an application summary document? I queried the documentation in your power design workshop and found no documentation detailing the various short circuit protection circuits. If you have one, please let me know.
Excuse me, do you have a good short circuit protection design circuit? It can not only have a capacitive load of 10000uF, that is, the overshoot current at startup does not trigger short circuit protection, and can reduce the short circuit loss, which is reduced from 40W to 10W.
The size of my prototype is 48V input, 5V16A output.
Thank you
