Patent ID: 8274304

Claim:
An alternating current (AC) power supply measuring circuit comprising: a first input terminal and a second input terminal, to receive an external AC voltage signal; a voltage dividing circuit to receive the AC voltage signal and divide the AC voltage signal to a first voltage dividing signal and a second voltage dividing signal, the voltage dividing circuit comprising first to fourth resistors connected between the first and second input terminals in series; a first dividing node between the first and second resistors outputting the first voltage dividing signal, a second dividing node between the third and fourth resistors outputting the second voltage dividing signal; a measuring integrated circuit (IC) to receive the first and second voltage dividing signals to obtain an AC voltage measuring signal; a control board to receive the AC voltage measuring signal and process the AC voltage measuring signal; and a first power rectifying circuit to provide a floating ground signal to the voltage dividing circuit, a ground node between the second and third resistors receiving the floating ground signal.