Oscillation circuit: Switching power supply oscillation circuit is divided into transistor oscillation circuit and integrated block oscillation circuit, such as STR-S series IC, TEA2104, TDA4601, TDA4605, TDA2261, TDA16846 and so on.
Voltage-stabilizing circuit: The voltage-stabilizing principle of the switching power supply adopts the pulse-width-adjusting voltage-stabilizing method, that is, by automatically changing the ratio of the off and on time of the switching power tube, or by changing the duty cycle of the oscillator output pulse. purpose of stabilization. The circuit of the voltage regulator part consists of three parts: sampling, comparison and control. Many cores are composed of ICs (such as SE110 and other ICs) and optocouplers, while some cores are composed of discrete components (mostly Domestic machines), and some of the power supply ICs used in the movement itself integrate this part of the circuit (such as some series switching power supply ICs).
Protection circuit: The color TV switching power supply is equipped with a protection circuit, and its protection method is to stop the circuit from vibrating. There are overcurrent protection, overvoltage protection and undervoltage protection (short circuit protection), as well as overheating protection. The overcurrent sampling point of the overcurrent protection circuit is on the emitter potential of the main vibration power tube in most TV sets. The sampling point of the overvoltage protection circuit is generally taken from the rectified and filtered voltage of 220V AC or the main load supply voltage, and is sampled and judged by a Zener diode (zener tube). The sampling point of the short-circuit protection circuit is generally on the low-voltage group power supply output by the regulated power supply, and a diode is used to discriminate and sample. "Latch circuit" is actually a protection execution circuit, and the signal sent from each sampling point is used to control the circuit to stop vibration.
