Patent ID: 7701176
Filing Date: 2010-04-20
Classification: H02J

Abstract:
1. A protective circuit for a secondary battery pack having a plurality of batteries, comprising: a sampling circuit generating pulses for selecting one or more of the batteries for inspection; a selection circuit for receiving said pulses and selecting a battery in the battery pack; a reference voltage source providing one or more reference levels, wherein the reference voltage source has a regulated output circuit that calibrates protection threshold voltages of the protective circuit; four or more voltage comparators each receiving one of the reference levels to compare with the level of the selected battery and generating one or more compared levels, wherein a first comparator detects over-charging of said batteries, a second comparator detects over-discharging of said batteries, a third comparator detects over-current through said batteries, and a fourth comparator detects a short circuit of said batteries, wherein the reference levels comprise, a first reference voltage, a second reference voltage, and a third reference voltage, and wherein the first reference voltage is input for said first comparator, the second reference voltage is input for said second comparator and for said fourth comparator, and the third reference voltage is input for said third comparator; battery status decision circuit connected to the comparators generating control signals as a function of the compared levels; and battery charging/discharging control circuit for controlling the charging or discharging of the selected battery in response to the control signals.