Protection circuit
AssigneesSony Corporation, Sony Chemical & Information Device Corporation
InventorsYuji Furuuchi, Kazutaka Furuta, Masami Kawazu
Life of this patent
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Abstract
A protection circuit is provided, which protects a battery pack from overcurrents and overvoltages using sensing means and a protection device having a heating resistor and a fuse element provided on a circuit board. This protection circuit allows for sharing a protection device regardless of the current rating and the voltage rating of the battery pack, thereby being manufactured at low costs.
Claims7
A protection circuit for protecting a battery pack having rechargeable batteries connected in series from overcurrents and overvoltages, the protection circuit comprising:
- a protection device having a heating resistor and a fuse element provided on a circuit board;
- and
- sensing means for detecting an overvoltage across any of the batteries in the battery pack and switching a current flowing into the heating resistor,
- wherein the fuse element is melted in an overcurrent condition, and in an overvoltage condition on any of the batteries,
- wherein the sensing means switches on the current flowing into the heating resistor wherein a voltage across the heating resistor is less than a voltage across a total number of batteries in the battery back, thereby causing the heating resistor to generate heat and the fuse element to be melted, and
- wherein the sensing means includes a FET, wherein a source terminal of the FET is connected between two batteries in the battery pack.
A protection circuit for protecting a battery pack having rechargeable batteries connected in series from overcurrents and overvoltages, the protection circuit comprising:
- protection devices each having a heating resistor and a fuse element provided on a circuit board;
- and
- sensing means for detecting an overvoltage across any of the batteries in the battery pack and switching a current flowing into the heating resistor,
- wherein the plurality of protection devices are connected in parallel,
- wherein in an overcurrent condition, the fuse element is melted at each protection device,
- and wherein in an overvoltage condition on any of the batteries, the sensing means switches on the current flowing into the heating resistor, thereby causing a voltage across a predetermined number of the batteries in the battery pack to be applied to the heating resistor of each protection device, causing the heating resistor to generate heat, and causing the fuse element to be melted, wherein the predetermined number of the batteries in the battery pack is less than a total number of batteries in the battery pack, wherein a voltage across the heating resistor is less than a voltage across a total number of batteries in the battery back, and wherein the sensing means includes a FET, wherein a source terminal of the FET is connected between two batteries in the battery pack.
Dependencies are inferred from the claim text.