5V, 2A isolated switching power supply circuit composed of TOP414G

100V, 250mA, surface mount, high speed switching diode

Probe domestic switch needle KG-300K needle head diameter is 3.0mm normally open switch needle

The isolated switching power supply circuit of 5V, 2A output composed of TOP414G is shown in the figure.

C1 is the input filter capacitor. VDz and VD1 form a primary side clamp protection circuit. R1 is the control terminal resistor and C2 is the bypass capacitor. The C10 connected in parallel between the TOP414GC-S terminals prevents the triggering of the power-off circuit from malfunctioning when high-frequency interference occurs at the control terminal. VD2 is an output rectifier diode, C3, C4, L, C5, and C6 output filters, and C9 is an output noise canceling capacitor. The external error amplifier consists of a shunt regulator TL431. When the output voltage fluctuates, the sampled voltage is obtained after dividing by R3 and R4, and compared with the reference voltage of TL431, an external control signal is generated, and then the current of the TOP414G control terminal is changed by the optical coupler PC817A, thereby adjusting the duty. It is more stable than Uo. The gain of the control loop is set by R2. After the feedback winding voltage is rectified and filtered by VD3 and C7, it supplies power to the infrared receiving tube in PC817A.