Re tune a current sensing-limiter in ATX power.

[arvinfx]

Hi,

I have a ATX power with kia494p IC. ( This IC is like TL494) and I need to reconfig the cirrent limiter or short-circuit protection to upper ampers.So how can I do this guys?

 

[duffy]

Need a schematic. The '494 has 2 independent error amps, one is generally used for voltage sensing and the other for current. What you want to do is find the one used for current, and look for a way to change the ratio of the resistances involved. Could be as simple as going from a .02Ω current-sensing resistor to .015Ω.

 

[arvinfx]

I could find voltage regulator at pin 1 thus other opamp will be for current sensing ?

 

[arvinfx]

I have checked my power circuit , but the 16 pin of kia494 is conected to GND!!! So who turn off my power how could!!!!

 

[arvinfx]

Nobody Knows!?

 

[arvinfx]

I made it!

My smps is made for voltage-mode feedback and with pin 4 puls shoutdown is sent when the -12v and -5v decrease down to -14v !

So I could increase current limite by change R29 to achieve this purpose.But I had same problem when the load was capacitive. This problem resolved by adding a 100uf capacitor between base and emitter of T6.