Alternating current state identification circuit based on AC signal detection

By using an AC signal detection-based AC power status recognition circuit, the problem of misjudgment in LED lamp dimming power supply systems during AC power outages is solved, enabling precise power supply mode switching and ensuring stable operation of LED lamps.

CN121968406APending Publication Date: 2026-05-01BOKE DRIVERS CO LTD
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Patent Information

Application Number
CN202610155945.3
Authority / Receiving Office
CN · China
Patent Type
Applications(China)
Current Assignee / Owner
Filing Date
2026-02-04
Publication Date
2026-05-01

AI Technical Summary

Technical Problem

Existing LED dimming power supply systems cannot accurately identify the AC power outage status when there is a sudden AC power failure, which leads to the false triggering of the DC emergency mode and causes abnormal problems such as LED flashback. This is especially true when the power supply is under no-load or light load, the slow release of charge in capacitor CX can cause misjudgment.

Method used

An AC power status identification circuit based on AC signal detection is adopted, including first and second sampling circuits, operational amplifier circuit, reference circuit, comparator circuit and signal amplification circuit. By reducing the down bias resistance value of the second sampling circuit, the AC power off state is accurately detected, and accurate power supply mode switching is achieved.

Benefits of technology

It achieves accurate identification during AC power outages, avoids accidental triggering of DC emergency mode, ensures stable power supply for LED lights, and prevents abnormal phenomena such as LED light flickering.

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Abstract

The invention discloses an alternating current state identification circuit based on AC signal detection, and the circuit comprises a first sampling circuit which is used for sampling the voltage value of alternating current; the second sampling circuit is used for sampling the voltage value of the alternating current; the operational amplifier circuit is used for presetting a voltage value and is used for merging a resistor into a lower bias resistance circuit of the second sampling circuit when the sampling voltage value of the first sampling circuit is greater than the preset voltage value so as to reduce the sampling voltage value of the second sampling circuit; the reference circuit is used for providing a reference voltage value; the comparison circuit is used for comparing the sampling voltage value of the second sampling circuit with a reference voltage value and outputting a comparison signal; and the signal amplification circuit is used for amplifying the comparison signal and sending the comparison signal to the dimming control circuit to enable the dimming control circuit to identify the alternating current state, so that the dimming control circuit more accurately detects the comparison signal of the alternating current turn-off pulse width time output by the comparison circuit, and accurate control switching of alternating current power supply or emergency direct current power supply is realized.
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