Rectify and filter the sine signal into 2.2V DC signal(The output of rectifier filter circuit is 2.2V at no load), and then use it as input to connect Vin of the development board. The voltage at vin is displayed as 0, and there is no output.
The rectifier and filter circuit I use is a unidirectional bridge rectifier circuit with parallel capacitance. The diode is Schottky diode 1N5819, and the filter capacitance is 1 μF. When I change the input (from 0.6V to 6V), the output remains unchanged and is fixed at 2.4V. Why?
thanks！
