Patent ID: 6075478
Filing Date: 2000-06-13
Classification: H03M

Abstract:
An A/D converter, comprising:a comparator that compares an analog input voltage against a reference voltage to generate a corresponding referencing result signal;a D/A converter that provides the reference voltage to the comparator in correspondence to a digital reference signal;a successive conversion register that provides the digital reference signal to the D/A converter under control of a conversion control signal;a conversion control device that provides the conversion control signal to the successive conversion register in correspondence to the referencing result signal;an output unit that holds the digital reference signal received from the successive conversion register and generates the digital reference signal as a digital output signal under control of the conversion control device; andan operating mode selection circuit that determines whether the analog input voltage is in a first state or a second state, enables an A/D conversion operation of the analog input voltage by entering a conversion mode when the analog input voltage is determined to be in the first state and disables the A/D conversion operation of the analog input voltage by entering a standby mode when the analog input voltage is determined to be in the second state;wherein the operating mode selection circuit includes a threshold value setting unit for setting a predetermined threshold value which indicates a range for which the analog input voltage is determined to be in the first state; andwherein the operating mode selection circuit includes a judging unit that compares the digital output signal against the threshold value, judges whether the analog input voltage is in the first state or the second state, based on said comparison, and generates a judgment signal indicating the judged first state or second state state.