DEVICES AND METHODS FOR PROTECTION OF RECHARGEABLE ELEMENTS

摘要

A protection circuit (37, 69, 100) for use with a charger (5, 1010, 186) and a chargeable element (1, 24, 124, 180, 222), comprising: a shunt regulator (39, 50, 105, 182, 232) comprising a transistor switch (51, 114), the transistor switch (51, 114) having first and second terminals for coupling in parallel across the chargeable element (1,24, 124, 180, 222), the transistor switch (51, 114) having a threshold ON voltage; and a first variable resistor (38, 62, 104, 184, 224, 236) thermally and electrically coupled to the transistor switch (51,114), the first variable resistor (38, 62, 104, 184, 224, 236) having a first terminal for coupling to the charger (5, 101, 186) in series and a second terminal for coupling to the chargeable element (1, 24, 124, 180, 222) in series, wherein the first variable resistor (38. 62, 104, 184, 224, 236) limits current flowing through the transistor switch (51, 114) during an overvoltage or overcurrent condition before the current reaches a level sufficient to cause the transistor switch (51, 114) to fail, wherein the shunt regulator (39, 50, 105, 182, 232) further comprises control circuitry (53, 55, 72), configured to activate the transistor switch (51, 114) if the voltage across the chargeable element (1, 24, 124, 180, 222) reaches the threshold ON voltage.