US 11,988,723 B2
Alternating-current detection circuit
Hu Xia, Shanghai (CN); Chunda Wu, Shanghai (CN); and Dongfeng Wang, Shanghai (CN)
Assigned to Shanghai Natlinear Electronics Co., Ltd., Shanghai (CN)
Appl. No. 18/021,815
Filed by Shanghai Natlinear Electronics Co., Ltd., Shanghai (CN)
PCT Filed Aug. 18, 2021, PCT No. PCT/CN2021/113278
§ 371(c)(1), (2) Date Aug. 29, 2023,
PCT Pub. No. WO2022/037618, PCT Pub. Date Feb. 24, 2022.
Claims priority of application No. 202010840567.5 (CN), filed on Aug. 20, 2020.
Prior Publication US 2024/0085492 A1, Mar. 14, 2024
Int. Cl. G01R 31/42 (2006.01)
CPC G01R 31/42 (2013.01) 10 Claims
OG exemplary drawing
 
1. An AC detection circuit, configured to detect a power supply state of an AC power supply for a load, wherein the AC detection circuit comprises:
a live wire input end and a neutral wire input end;
a first diode and a second diode with anodes connected to each other, wherein the first diode and the second diode are both Zener diodes, and a cathode of the second diode is grounded;
a first resistor, having a first end connected to the live wire input end, and a second end connected to a cathode of the first diode;
a second resistor, having a first end connected to the neutral wire input end, and a second end connected to the cathode of the second diode;
a rectification module, connected to the live wire input end and the neutral wire input end;
a power supply, configured to supply power to the AC detection circuit;
a current mirror module, having an input end, a first output end and a second output end, wherein the input end of the current mirror module is connected to the power supply, and a value of the current outputted from the first output end of the current mirror module and a value of the current outputted from the second output end of the current mirror module have a fixed ratio;
a unidirectional conduction module, configured to enable unidirectional conduction of the current from the first output end of the current mirror module to the cathode of the first diode; and
a current comparison module, configured to compare a current value of the second output end of the current mirror module with a reference current value and output a comparison result, wherein the current comparison module comprises: an oscillator, a timer, a current comparator and a reference current source; the oscillator is configured to generate a periodic oscillation signal as a clock signal of the timer; the current comparator is provided with a first input end, a second input end and an output end, wherein the first input end of the current comparator is connected to the second output end of the current mirror module, the second input end of the current comparator is connected to the reference current source, and the output end of the current comparator is connected to the timer; the current comparator compares the current value of the second output end of the current mirror module with the reference current value of the reference current source, and outputs a comparison result signal; and the timer is set with a timer value, and the comparison result signal is outputted after the comparison result signal maintains for the time of the timer value.