ANALOG/DIGITAL CONVERTER

PURPOSE:To omit a troublesome adjustment by utilizing the designed value of two known states with respect to the output frequency and the reference input of a V/F converter. CONSTITUTION:The output current (i) of a power converter of a semiconductor power converter 11 is converted into a detection signal Vin by a sensor 1, an offset voltage Voffset is added by an adder 2 from a reference voltage generator 3 and a pulse train Fout is outputted via a V/F converter 4. Counters 5, 7 count the pulse Fout and the reference clock (f) and a sampling timing signal S resets the count to 0. Data latches 6, 8 counts C, T just before the reset by the signal S, the result is read in a CPU 10 via a data control bus 9, the output current of the power converter is detected and operated to obtain a digital quantity. The CPU 10 applies further current adjustment and applies the control of the output current (i) to the converter 11 as a current command. Thus, the troublesome adjustment is omitted.