JPS6484157A - Method and device for current detection - Google Patents

Abstract

PURPOSE:To reduce the size of the device and lessen the influence of a pulsating component, and to enable high-accuracy current detection up to a low current area by converting a current into pulses proportional to its current value and counting the pulses, and then generating a pulse counted value. CONSTITUTION:When such a high current that the pulses is inputted at, for example, a sampling period Tc is supplied, a multiplied pulse signal is counted by a reversible counter 22 and the counted values M(i-1) and M(i) are stored in a register A23 every time a pulse is inputted. A counter 25, on the other hand, counts a reference clock and T(i-1) and T(I) are stored as time counted values in a register A26 every time a multiplied pulse is inputted. Then the contents of the registers A23 and A26 are stored in registers B24 and B27 and then read out at the time of sampling S(i-1) and S(i). The read current counted value M and time counted value T are therefore values at the time of pulse signal input and irrelevant to the sampling period Tss. The current value Im is therefore calculated with hgh accuracy from IM=KXM(i)-M(i-1)/T(i)-T (i-1) (T: constant).