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Switching power supply protection circuit based on UC3842

A technology for protecting circuits and switching power supplies, applied to electrical components, output power conversion devices, etc., can solve problems such as inability to play a protective role, and achieve the effect of simplifying output power and simplifying frequency compensation

Pending Publication Date: 2018-04-20
MIANYANG HIGHLY TECH JINGWEIDA SCI
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] The purpose of this utility model is to solve the problem that the existing switching power supply protection circuit based on UC3842 cannot play a good protective role when there is overload protection and overcurrent protection, and there are certain defects.

Method used

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  • Switching power supply protection circuit based on UC3842
  • Switching power supply protection circuit based on UC3842

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Embodiment Construction

[0015] The technical solution in this embodiment will be clearly and completely described below in conjunction with the accompanying drawings in the embodiment of the present invention. Obviously, the described embodiment is only a part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

[0016] A switching power supply protection circuit based on UC3842, including a rectifier circuit, a high-frequency transformer, a MOS power tube, and a current-mode pulse width modulation chip UC3842. The sampling voltage of the chip UC3842 is connected to an emitter follower, and the sampling resistor is a non-inductive resistor. , The feedback circuit is controlled by TL431 plus optocoupler.

[0017] Specifically, the circuit is as follows: 220V AC is connected...

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Abstract

The invention discloses a switching power supply protection circuit based on UC3842, and relates to the field of electronic technology power supplies. The circuit comprises a rectifier circuit, a highfrequency transformer, a MOS power transistor and a current type pulse width modulation chip UC3842. An emitter follower is connected with the sampling voltage site of the chip UC3842. A sampling resistor is a non-inductive resistor. A feedback circuit is controlled by TL431 and an optocoupler. According to the invention, the emitter follower is connected with the sampling voltage site of the UC3842; an artificial slope synchronized with a pulse width modulation clock is added to the control voltage; delta I disturbance can be reduced to zero in the subsequent period; and even if the system works under duty cycle greater than 50% or continuous inductor current conditions, the system is stable.

Description

technical field [0001] The invention relates to the field of electronic technology power supply, in particular to a switching power supply protection circuit based on UC3842. Background technique [0002] UC3842 is a current-controlled pulse width modulation chip with excellent performance produced by Unltmde Company in the United States. It has the characteristics of small number of pins and simple peripheral circuits, so it has been widely used. However, with the increase of the switching frequency of UC3842, many problems have appeared in the protection circuit of the switching power supply formed by it. The typical application circuit of UC3842 is as figure 1 As shown, this circuit has some disadvantages: (1) The defect of overload protection; when the power supply is overloaded or the output is short-circuited, the protection circuit of UC3842 will act, so that the duty cycle of the output pulse will be reduced, the output voltage will be reduced, and the power supply ...

Claims

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Application Information

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IPC IPC(8): H02M1/32
CPCH02M1/32
Inventor 余代春
Owner MIANYANG HIGHLY TECH JINGWEIDA SCI
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