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Short-circuit and under-voltage protection method for 12V120W direct-current power converter

A power converter and short-circuit protection technology, applied in the electrical field, can solve problems such as electrical damage

Inactive Publication Date: 2020-05-19
徐州大工电子科技有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] The purpose of the present invention is to provide a 12V120W DC power converter short circuit and undervoltage protection method to solve the problem that the power converter may cause damage to electrical appliances due to short circuit or undervoltage

Method used

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  • Short-circuit and under-voltage protection method for 12V120W direct-current power converter
  • Short-circuit and under-voltage protection method for 12V120W direct-current power converter
  • Short-circuit and under-voltage protection method for 12V120W direct-current power converter

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Embodiment Construction

[0018] Such as figure 2 and image 3 As shown, a 12V120W DC power converter short-circuit protection method: when the output of the power converter is overloaded or short-circuited, the output voltage will drop. According to this characteristic, the low-power control chip U5 is used to detect the output voltage. When the detection result is lower than After a certain voltage, send a signal to control the COMP pin of the power converter chip UC3845, pull down this pin to control the PWM pin of the power conversion chip UC3845 to stop output, and then the entire converter has no output, and the short circuit phenomenon is also maintained under this condition. There will be no problems, the specific method is:

[0019] Connect pin 7 of the low-power control chip U5 to the voltage output terminal of the power converter through the converter output voltage detection circuit to detect the output voltage of the power conversion chip UC3845; connect pin 1 of the low-power control ch...

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Abstract

The invention relates to a short-circuit and under-voltage protection method for a 12V120W direct-current power converter. When a system is powered on and delayed for a period of time, voltage dividerresistors R21 and R23 are used for detecting the output voltage; after voltage division, a pin 7 of a low-power-consumption control chip U5 detects a low level, which means that external short circuit or overcurrent occurs; the output of a pin 4 of the low-power-consumption control chip U5 is changed from a low level to a high level, a triode Q5 is controlled to be conducted, an optocoupler primary side diode is conducted, and a secondary side triode is conducted; a COMP pin of a power supply conversion chip UC3845 is pulled down, the OUT pin of the UC3845 is controlled to stop outputting a PWM signal, and then, the whole converter does not output, namely, the power supply converter is in an open-circuit state, and in the state, even if the output continues to maintain a short circuit phenomenon, the problem that an electric device is damaged does not occur; and the short circuit is cancelled after the control, the power supply ACC is restarted, and the converter resumes work.

Description

technical field [0001] The invention relates to the field of electricity, and specifically discloses a short-circuit and under-voltage protection method for a 12V120W DC power converter. Background technique [0002] The power converter circuit uses Pulse width modulation, PWM technology, controlled by the current mode chip UC3845. Such as figure 1 As shown, the PWM signal output by pin 6 of the UC3845 chip controls the on and off of the MOS transistor M1 through the drive resistor R1. After the high and low level signals output by the MOS tube are processed by the energy storage inductor L1 and the freewheeling diode D1, the converter can output voltage stably. Among them, C1 is the output filter capacitor, and C2 is the input filter capacitor. [0003] When the output short circuit occurs, the current is several times or even dozens of times higher than the rated current. At this time, the threshold voltage of the current sampling comparator will be internally clamped t...

Claims

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Application Information

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IPC IPC(8): H02H7/12
CPCH02H7/1213
Inventor 张帅帅刘运胜
Owner 徐州大工电子科技有限公司
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