Disclosed are an audio ADC for supporting voice wake-up and an electronic device. The audio ADC includes a programmable gain amplifier (PGA) having an input terminal for receiving an audio signal; a bypass switch having an input terminal for receiving an analog audio signal; and a successive approximation ADC having input terminals respectively connected to output terminals of the PGA and the bypass switch; the PGA gains and amplifies the audio signal, the bypass switch bypasses the PGA, and outputs the analog audio signal; the successive approximation performs analog-to-digital conversion with noise shaping on the analog audio signal after gain amplification at a first sampling rate/oversampling rate when the audio ADC is normal working, and turns off noise shaping when the audio ADC is sleep, performs analog-to-digital conversion on the analog audio signal output by the bypass switch at a second sampling rate/oversampling rate, and outputs to a DSP.