Patent ID: 6285165
Filing Date: 2001-09-04
Classification: H02J

Abstract:
A secondary battery protection circuit for controlling charging of a secondary battery, comprising:a first transistor having either an emitter or a collector the first transistor coupled in parallel to a power line which couples a secondary battery which is to be charged and a battery charger, a base of said first transistor being coupled to said power line via either a resistor or a leak absorption circuit;a second transistor having either a collector or an emitter thereof coupled to the base of said first transistor; anda clamping circuit having a node coupled to either the emitter or the collector of said second transistor, the clamping circuit clamping the node at or above ground level when active,said clamping circuit being inactive and said second transistor being turned ON to turn ON said first transistor when a residual voltage of said secondary battery is near 0 V and said clamping circuit being active and turning OFF said second transistor when the residual voltage of said secondary battery is at or above a predetermined potential.