Lithium-ion over voltage protection circuit

Abstract

The present invention is directed to an overvoltage disconnect circuit for a lithium ion battery and/or cell. The lithium ion battery has at least one lithium ion battery cell having a rated voltage or a desired voltage, an input terminal, and being chargeable by a charger. The overvoltage disconnect circuit has (1) a switch unit, and (2 & 3) a first and second voltage dividers connected to (4) a comparator. The switch unit is in series with the lithium ion cell and the charger and the gate of the switch unit is connected to the comparator. The first voltage divider receives the voltage of the charger and generates a second charge. The second charge is proportionally below the voltage of the charger. The second voltage divider receives the voltage of the charger and generates a predetermined charge; the predetermined charge is proportionally below and sometimes less than the rated voltage or the desired voltage of the cell. The comparator compares the predetermined charge to the second charge. If the second charge is below the predetermined charge, the comparator transmits a an operational signal (which can be a non-signal) to the switch unit that allows the charger to continue charging the lithium ion cell; And if the second charge is equal to or greater than the predetermined charge, the comparator transmits the operational signal to the switch unit that disconnects the charger from charging the lithium ion cell.

Dependencies are inferred from the claim text.