Patent ID: 6791809
Filing Date: 2004-09-14
Classification: H02J

Abstract:
A charge/discharge protection circuit for a battery, comprising:a protection circuit having a first, a second, and a third terminal, where said first and said second terminal are coupled to battery terminals of at least one rechargeable cell, where said second and said third terminal are coupled to charge/discharge terminals of an external device, said protection circuit protecting said battery from an over-voltage from said external device, said protection circuit further comprising: a first serial circuit comprising a fusible link and a load current switch, said first serial circuit coupled between said first terminal and said third terminal, where said load current switch is controlled by a control logic, and where a plurality n of said first serial circuits are coupled in parallel, such that there are n said fusible links and n said load current switches; a second serial circuit comprising a switch segment, where said second serial circuit is coupled between the junction of said fusible link and said load current switch and said second terminal, where said switch segment is controlled by said control logic, and where a plurality n of such second serial circuits are coupled in parallel, such that there are n switch segments, where the plurality n of such switch segments is called a short-circuit switch array; and said control logic coupled between said second and said third terminal, said control logic detecting the conditions of under-voltage and over-voltage at said first and said second terminals, over-current, under-current, and over-voltage at said second and said third terminals, where said control logic generates first and second control signals in response to said conditions, such that said first control signal controls the opening and closing of each of said switch segments of said short-circuit switch array and said second control signal controls the opening and closing of each of said load current switches, were said second control signal causes all n of said load current switches to open simultaneously, thereby separating said battery from said external device, were, upon detecting an over-voltage at said second and said third terminals, said first and said second signal causes all n of said load current switches to close simultaneously, then to open sequentially said short-circuit switch array, thereby causing to melt sequentially all n of said fusible links, to open immediately and sequentially a first number of said load current switches after having closed all n of them earlier, following the opening of the last of said first number of said load current switches to then close simultaneously said first number of said load current switches, which then is followed by the simultaneous opening of the second remaining number of said load current switches.