15V／3.5A 52W switching power supply circuit diagram composed of MC33374T／TV

Published:2011/3/23 22:32:00 Author:Nicole | Keyword: 52W switching power supply | From:SeekIC

15V/3.5A 52W switching power supply circuit composed of MC33374T/TV as shown. The allowed range of AC input voltage is 92 ~ 276V. Rectifier bridge VD1 ~ VD4 use four 1N5406 3A/600V silicon rectifier tubes. Primary protection circuit is composed of RC absorber circuit (R2, C2) and the clamp circuit (VDz, VD5), it can effectively suppress the peak voltage due to the leakage of high-frequency transformer, to protect the internal power switch of MC33374 from damaged. VDz adopts P6KE200A transient voltage to suppress the diode(TVS), then the reverse breakdown voltage UB = 200V. VD5 uses MURl60 super fast recovery diode (SRD). Note, the serial number of RC R1, C3 in the figure is vacant, according to the need, it can turn the series circuit of R2, C2 into the R1 (20kΩ, 2W) and C3 (0.1μF, 400V) in parallel and then serial ultrafast recovery diode, formed R, C, VD protection circuit. C5 is the bypass capacitor of Vcc side. S for control switching power supply, the key of on/of. After in series with R7 S, it can improve the reliability of mode conversion. VD6 and C6 form the high-frequency rectifier filter of the feedback coil output. Secondary high-frequency rectifier uses Schottky diode with high current, low voltage the model is MBR20100CT (20A/100V). The tube is common cathode, the two negative electrodes (cathode) are short circuited interiorly, it needs the two positive(anode) connected in parallel externally. C8, C11, L, C12 and C13 form the output filter circuit. In view of the inductance of filter inductance L is small, only 5.0μH, and large-capacity filter capacitors C8, Cl1 have equivalent inductance Lo, it will directly affect the actual inductance from L into L + Lo, so it should take the voice φ0.55mm enamelled wire with 7-turn around the feeder ring N3, and around the middle of the frame, to reduce leakage; also should around two layers of polyester film. The model of ferrite core is E25. In order to prevent saturated magnetization, it should stay out of the air gap of 0.43mm between the two E-shaped cores.



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