AC/DC Switching Power Adapter Chip Main Advantages and Selection
AC/DC switching power adapter chip (or module), as long as with some resistive components and a switching transformer, can be made into a basic switching power adapter.
The main working principle of an ordinary half-bridge switching power adapter is that the switching tubes of the upper and lower bridges (the switching tubes are VMOS when the frequency is high) conduct in turn. Firstly, the current flows in through the switching tubes of the upper bridge, and using the storage function of the inductor coil, the electric energy is gathered in the coil, and finally, the upper bridge switching tubes are closed, and the switching tubes of the lower bridge are opened, and the inductor coils and capacitors continue to supply the power to the outside. Then the lower bridge switching tube is turned off again, and the upper bridge is turned on again to let the current in, and so on and so forth. It is called a switching power adapter because the two switching tubes are switched on and off in turn.
As a switching power IC in an AC-DC class power adapter. the main advantages of AC/DC switching power adapters:
a: small size and light weight (volume and weight of only 20% to 30% of the linear power adapter),
b: high efficiency (generally 60% to 70%, while the linear power adapter only 30% to 40%),
Self-immunity, wide output voltage range, modular.
Commonly used low-voltage AC switching power adapter will 220VAC power after EMI filter directly rectified into 300V or so of AC voltage, through the circuit control switching tube for high-speed conduction and cut-off and then converted to high-frequency AC power provided to the transformer for the transformer, thus generating the required set or more voltage, and then rectified into the required voltage of AC power.
