Disclosed are an impedance detection device and method which can detect the impedance of a load. In an embodiment, the impedance detection device comprises an alternating-current
signal generation circuit, an output buffer, a
current mirror, a detection impedor, a
clock pulse generation circuit, a comparison circuit and a
control circuit; the alternating-current
signal generation circuit is used for providing an alternating-current
signal; the output buffer is used for generating output
voltage and output current according to the alternating-current signal and the impedance of the load; the
current mirror is used for generating image current according to the output current; the detection impedor is used for generating detection
voltage according to the image current; the
clock pulse generation circuit is used for providing a
clock pulse; the comparison circuit is used for comparing the output
voltage with the detection voltage according to the clock pulse so as to generate a comparison result; the
control circuit is coupled to the comparison circuit and at least one of the
current mirror and the detection impedor and used for regulating at least one of the proportion between the image current and the output current and the impedance of the detection impedor according to the comparison result till the comparison result meets a preset condition. By the impedance detection device and method, abnormal sound can be avoided.