Hitachi Maxell, Limited

Other

Hitachi, Ltd.

Hitachi Ulsi Systems Co., Ltd.

Hitachi Microcomputer System, Ltd.

Shinji Tanaka

Takeshi Yamaguchi

Takashi Takeuchi

Masaru Noda

Mitsunori Tsuchiya

Takehisa Yokohama

Eiji Matsumasa

Yosifumi Sakaguchi

Kouichi Horisaki

An apparatus for detecting an integrated value of current flow. The apparatus includes an integrator having an integration capacitor, to which a current sensor voltage is inputted, for outputting an output voltage corresponding to an integrated value of the current sensor voltage, and a resetting circuit for clearing integration electric charges accumulated in the integration capacitor to reset the integrator when the output voltage has reached an upper threshold value or a lower threshold value. The apparatus also includes a counter for counting the number of resets of the integrator in an upper direction or in a lower direction, and a connection-polarity inverting circuit for inverting a polarity of inputting of the current sensor voltage to the integrator, a polarity of connecting of the integration capacitor to the integrator and a counting direction of the counter, alternatively, at a regular time interval and synchronously. An integrated value of current flow is obtained on the basis of a count value of the counter.

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

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.

Means for detecting the integrated value of current flow, a means for

A protection circuit device for protecting a secondary battery from an overcharge and/or an overdischarge has first and second terminals, across which a charger and a load are alternatively connectable. A first switch and/or a second switch may be provided in series with the secondary battery between the first and second terminals. In a charging operation mode, the second switch is kept conductive. A charging operation is performed with the first switch made conductive. When the battery is overcharged for some reasons, the first switch is turned off. Upon connection of a load across the first and second terminals, the first switch is restored to a conductive state for a discharging operation which releases the battery from an overdischarge state. In a discharging operation mode, the first switch is kept conductive. A discharge operation is performed with the second switch made conductive. When the battery is overdischarged, the second switch is caused to remain conductive even after commencement of the overdischarge, so that the battery can continue the discharge operation if the temporary overdischarge does not last longer than the predetermined period of time.

Secondary battery protection device from overcharge/overdischarge

Growing community of inventors

Ome, Japan

Shinji Tanaka