The MAX1906 protects against overvoltage conditions in lithium-ion/lithium polymer (Li+) battery packs by blowing a three-terminal protection fuse. The IC should be used in conjunction with resettable protection circuits to provide a high level of safety against overcharging Li+ batteries. It can be used with 2-, 3-, or 4-series cell battery packs. The MAX1906 monitors individual cell voltages. If any cell voltage exceeds the overvoltage threshold for greater than 2.1s, the MAX1906 activates an internal SCR. The SCR sinks sufficient current to blow an external protection fuse, permanently disabling the battery pack. Alternatively, the IC can drive the gate of an external MOSFET to blow the fuse. The MAX1906 also offers protection against disconnected voltage sense pins. If a disconnected pin is detected, the DISCON output is forced low. The MAX1906 includes a test mode, which determines if the circuit is operating correctly while in an assembled battery pack. The low-cost MAX1906 is available in a thermally enhanced 16-pin QFN package. Applications * 2-, 3-, or 4-Series Li+ Battery Packs for Portable Products