Means for detecting the integrated value of current flow, a means for detecting the value of current flow and a battery pack employing those means

摘要

The present invention provides apparatus for detecting the integrated value of current flow, apparatus for detecting the value of current flow and a battery pack employing those apparatus each of which becomes insensitive to the offset in an operational amplifier. Each apparatus and the battery pack includes: a current sensor resistor inserted in series with a current path; an integrator; an input status selector; an integration capacitor connected to the integrator; and a connection-polarity inverter of the integration capacitor provided between the integrator and the integration capacitor. The input status selector switches alternately so as to provide two statuses of a status a and a status b at intervals of a predetermined time which are equal to one another, and in the status a, introduces therethrough the voltage which corresponds to the battery current value and which is developed across terminals of the current sensor resistor into an input of the integrator, while in the status b, inverts the polarity of the current sensor voltage developed across the terminals of the current sensor resistor to introduce therethrough the resultant voltage into the input of the integrator, or to introduce therethrough the voltage of zero to the input of the integrator.