Hi all,
Attached is a Voltage mode control SMPS. When the circuit is switched on without giving a feedback to the SG3525 controller the output voltage that i got is +/- 45V...
Can anyone advise me on how am i to get +/- 25V could it be done by adjusting the zener values of the feedback circuit ?
After 3 times switching the circuit on and off for testing purpose, my mosfet and the controller IC were toasted...later found that that one out of 4 of the mur1520 (switching diode) is not working. perhaps i guess that would be reason to short the circuit and burn the mosfet.
Attached is a Voltage mode control SMPS. When the circuit is switched on without giving a feedback to the SG3525 controller the output voltage that i got is +/- 45V...
Can anyone advise me on how am i to get +/- 25V could it be done by adjusting the zener values of the feedback circuit ?
After 3 times switching the circuit on and off for testing purpose, my mosfet and the controller IC were toasted...later found that that one out of 4 of the mur1520 (switching diode) is not working. perhaps i guess that would be reason to short the circuit and burn the mosfet.
Attachments
To begin you need LC filters in both the plus and minus output circuits. The transformer turns ratio needs to be selected to be compatible with the desired output voltages. For plus and minus 25 volts output the total zener voltage should be in the range of 49 volts.
I didn't look much at the rest of the circuit, but the 1K resistor at -In seems too low. 100uF on the comp pin is way too large.
I didn't look much at the rest of the circuit, but the 1K resistor at -In seems too low. 100uF on the comp pin is way too large.
Hi
Why do you all use so small values of caps with IR, it won't kill you to put 10uF or even 100u to be sure it will hold that charge for fet drive...and it only needs to be 16v, no need for 100v...
Also you don't need 1000u on primary side, 330u will be enough, since output voltage is only +/-25v so I don't think this will push a lot of power....
Gate resistors would be better to be 22R, no need to go lower
Use 470u instead of 33u with 7812, again it won't kill you to use bigger values...
And with this FB you will get +/-30v...
Again since I don't think this will push any big powers, you can use 1A fuse, 3.15 if you really need...
And those 33k resistors on primary side can be 2w only...
Why do you all use so small values of caps with IR, it won't kill you to put 10uF or even 100u to be sure it will hold that charge for fet drive...and it only needs to be 16v, no need for 100v...
Also you don't need 1000u on primary side, 330u will be enough, since output voltage is only +/-25v so I don't think this will push a lot of power....
Gate resistors would be better to be 22R, no need to go lower
Use 470u instead of 33u with 7812, again it won't kill you to use bigger values...
And with this FB you will get +/-30v...
Again since I don't think this will push any big powers, you can use 1A fuse, 3.15 if you really need...
And those 33k resistors on primary side can be 2w only...
hi
Looking at my transformer data each secondary is designed for 54 Volts when the input is 240.
the value i am getting +- 48 is by considering dead time and secondary diode drops.. this is without connecting the feedback.
when i connect feedback, of zener voltage of 50Vz ..is it possible for me to get +/- 25V as my output...
Looking at my transformer data each secondary is designed for 54 Volts when the input is 240.
the value i am getting +- 48 is by considering dead time and secondary diode drops.. this is without connecting the feedback.
when i connect feedback, of zener voltage of 50Vz ..is it possible for me to get +/- 25V as my output...
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