Small power switching power supply based on UC3843

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Summary:

The switching power supply has the advantages that the power frequency transformer does not have. The new, high-efficiency and energy-saving switching power supply represents the development direction of the regulated power supply. Because the switching power supply works inside the high frequency state, its power consumption is very low, and the power efficiency can be Doing higher, generally can achieve 80%, or even close to 90%. This high efficiency is not comparable to the normal power frequency transformer regulated power supply. The single-ended or double-ended output pulse width modulation (PWM) commonly used in switching power supplies eliminates the cumbersome power frequency transformer and can be used for power supplies ranging from a few watts to several kilowatts. There are many integrated circuits for pulse width modulation. We are now introducing the general characteristics of the UC3843 integrated circuit and the method by which it constitutes a small power switching power supply.

Main features of UC3843

Figure 1 is an outline view of the UC3842-UC3845. UC3843 is a new type of pulse width modulation integrated circuit that has been introduced in recent years. It has the features of full function, high operating frequency, and low external components. Its voltage regulation rate can reach 0.01%V, which is very close to the adjustment of linear regulated power supply. rate. The operating frequency is up to 500kHz and the starting current is only 1mA, so its starting circuit is very simple.

Here are the main features:
Optimized offline DC-DC converter with low quiescent current (1mA)
Fast automatic compensation circuit Single-step pulse control circuit Enhanced load feedback characteristics Power-down stagnation characteristics Double-pulse suppression High-current identification output Built-in gap reference voltage
500kHz operating frequency low Ro zero-crossing amplifier

See the PDF document for details of the small power switching power supply made by UC3843.