[SOLVED] Boost converter Audiable Noise Problem

[FMradio]

sir

i have designed a simple Boost converter 12v to 24V, with feedback control using uc3845, it works great the Inductor switching frequency is 55Khz, the problem is that it makes an audiable Noise which varies according to the load like SSsssssssssTTTttttttTTTTttssssssss ..

 

[FvM]

Audible noise usually indicates unstable feedback loop, or e.g. subharmonic frequencies that can occur in a current mode converter without suitable slope compensation.

 

[FMradio]

Audible noise usually indicates unstable feedback loop, or e.g. subharmonic frequencies that can occur in a current mode converter without suitable slope compensation.

Sir but its regulating the Voltage perfect am not facing any Problem, the Problem is just with the Audible NOSIE how i can supress it ??

please tell me how to do proper slope compensation????

my circuit consist of just MOSFET, Inductor, Diode, Capacitor & UC3845, + i am not using current feedback

 

[FvM]

Without current sense, UC3845 can only provide hysteretic (on-off) regulation. Stable duty cycle and respective silent operation can't be expected this way.

P.S.: There's possbly a way to feed a sawtooth voltage from pin RtCt to the current sense input. I don't see a reference circuit from manufacturer, but it should work if the sawtooth waveform is divided down to the voltage range of current feedback input.

 

[ch wazir]

It's most probably due to saturation of transformer causing noise for more current demand,replace transformer if possible.Regards

 

[FMradio]

It's most probably due to saturation of transformer causing noise for more current demand,replace transformer if possible.Regards

Sir it has no Transformer just an Inductor

---------- Post added at 19:54 ---------- Previous post was at 18:48 ----------

Sir FvM my Problem has been solved the Problem was with Current Sense, by inserting it in the loop its running pretty Silent Thank You Sir