Undervoltage protection circuit and switching power supply

By using a current source circuit to draw current from the voltage comparator circuit during the voltage rise phase of the switching power supply and stopping after the voltage stabilizes, combined with hysteresis protection, the problem of frequent triggering of traditional undervoltage protection circuits due to voltage oscillations is solved, thus achieving reliable startup and stable output of the switching power supply.

CN121710115BActive Publication Date: 2026-05-26SHENZHEN POWEROAK NEWENER CO LTD
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Patent Information

Authority / Receiving Office
CN · China
Patent Type
Patents(China)
Current Assignee / Owner
SHENZHEN POWEROAK NEWENER CO LTD
Filing Date
2026-02-04
Publication Date
2026-05-26

AI Technical Summary

Technical Problem

Traditional undervoltage protection circuits frequently trigger protection actions when the input power supply voltage fluctuates, leading to abnormalities in the power management chip and back-end circuits.

Method used

The controller monitors the voltage and draws current from the voltage comparator circuit during the voltage rise phase of the switching power supply through a current source circuit. The current draw stops after the voltage is fully established, ensuring the stability of the turn-on voltage. Hysteresis protection is achieved by combining the voltage comparator and output control circuits.

Benefits of technology

It improves the startup reliability of the switching power supply, avoids frequent protection actions near the critical voltage point, and ensures stable power output.

✦ Generated by Eureka AI based on patent content.

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    Figure CN121710115B_ABST
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Abstract

This disclosure presents an undervoltage protection circuit and a switching power supply. The undervoltage protection circuit includes: a controller configured to operate a current source circuit when the voltage at the second node is greater than a first voltage; and to deactivate the current source circuit when the voltage at the second node is less than or equal to the first voltage; the current source circuit, when operating, draws current from a voltage comparison circuit through the first node; the voltage comparison circuit is configured to output a first voltage to the second node when the voltage of the switching power supply meets a first condition; and to output a second voltage to the second node when the voltage of the switching power supply meets a second condition; an output control circuit is configured to control the switching power supply to output externally when the voltage at the second node is the first voltage; and to control the switching power supply to stop outputting externally when the voltage at the second node is the second voltage. This undervoltage protection circuit and switching power supply enable reliable startup of the switching power supply.
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