Electronics Projects, 42V 300W SMPS UC2525 MC34262 PCF article
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UC2525 Designed smps switching power supply contains corrector pfc power factor and switching push-pull converter involved in a half-bridge. PFC The control circuit for the corrector power factor was chosen MC34262 The involvement of this circuit in the design corresponds to the wiring shown in the data sheet. During the operation of the control circuit powered by an auxiliary winding, the coils of the corrector power factor.
Coil corrector power factor is wound on the core ETD29 with an air gap. The main winding coil has NP = 55 turns and is wound a high-frequency cable. The first the auxiliary winding are used to detect the zero current of the main winding coil and to the power supply circuit MC34262. The second auxiliary winding is used to provide power the control circuit UC2525
UC2525 SMPS Circuit
For the control of the converter connected to a half bridge is used an integrated circuit UC2525 The internal circuit is in figure 3.2. Since this circuit is located on the the secondary side of the source, is its power supply after turning on the power to ensure the auxiliary winding the coils of the corrector power factor T3
After several iterations, was selected the core of ETD39. The primary winding N1 will have 38 turns, a secondary winding (42 In) N2 14 turns and the second secondary winding N3 6 turns. For this number of turns is based on the inductance of the winding L1 = 3899 µH, L2 = 529 µH and L3 = 97,2 µH. The winding N1 will be wound three-wire with a diameter of 0.5 mm, the N2 four-wire with a diameter of 0.65 mm and a winding N3 one conductor with a diameter of 0.5 mm. For these averages wires would average current density should not exceed 3 a/mm2. Windings N1 and N2 are wound of multiple conductors of smaller diameter to be scaled effect of the surface currents.
PFC 300W Smps circuit pcb schematic all files alternative links: 42v-300w-smps-uc2525-mc34262-pcf.rar alternative link2