AUXILIARY WINDING MEASUREMENT METHOD AND CIRCUIT

The present invention provides an auxiliary winding measurement method and circuit. The measurement method and circuit are based on existing circuit elements, do not need extra cost, and enable auxiliary winding clamping topology to be more practical. The method specifically comprises: clamping a measurement pin to a power supply voltage in an excitation stage, so that the current flowing into the measurement pin is proportional to an input voltage, and the accurate measurement of the input voltage is achieved; making a voltage difference between the power supply voltage and the voltage of the measurement pin fall onto one internal resistor at a demagnetization stage, then transferring the current flowing through the resistor to another internal resistor, and using a sampling and holding circuit to sample and store the voltage of the other internal resistor, thereby achieving the accurate measurement of an output voltage; and comparing the voltage of the measurement pin with the voltage of a power supply pin,