berger.h
Member level 5
Hello I have ATX PS drived by SDG2921
STB +5V works fine
If I ground PS-ON, Pin 9 REM on IC
appears on C1 C2 (7,8) PWM 15us/15us, this PWM drive 2pcs NPN they ground winding of exciting trasnsformer (center is powered +5 from +5STB) and this should control a large NPN on the primary.
I thing standard ATX PS.
I checked everything and is fine.
But on output is on +12V only 800mV etc. and output C1 C2 still generates PWM.
My question is SDG2921 have OVP and UVP protection , on UVP is 280ms delay line and I thing UVP should shut down PWM outpu if all output voltage is not in normal after 280ms.
yes or not?
Internal schematics for IC is in datasheet.View attachment SDC2921_ENa.pdf
STB +5V works fine
If I ground PS-ON, Pin 9 REM on IC
appears on C1 C2 (7,8) PWM 15us/15us, this PWM drive 2pcs NPN they ground winding of exciting trasnsformer (center is powered +5 from +5STB) and this should control a large NPN on the primary.
I thing standard ATX PS.
I checked everything and is fine.
But on output is on +12V only 800mV etc. and output C1 C2 still generates PWM.
My question is SDG2921 have OVP and UVP protection , on UVP is 280ms delay line and I thing UVP should shut down PWM outpu if all output voltage is not in normal after 280ms.
yes or not?
Internal schematics for IC is in datasheet.View attachment SDC2921_ENa.pdf
