The UCC3957 is a BiCMOS process three or four cell Li-Ion battery pack protection device designed to work with external P-channel MOSFETs. Utilizing an external P-channel MOSFET provides no benefit to system losses during overdischarge, protecting the IC from damage to the battery during overcharge. An internal state machine operates continuously, protecting each Li-Ion battery from charging and discharging. A separate overcurrent protection block protects the battery pack from overdischarge currents. If any battery voltage exceeds the overvoltage threshold, the corresponding external P-channel MOSFET is turned off, preventing further charging current. An external N-channel MOSFET is required to transfer to this level a high-side P-channel MOSFET. The discharge current can still flow through the second P-channel MOSFET. Likewise, if any battery voltage falls below the undervoltage limit, the second P-channel MOSFET turns off and only charging current is allowed. Such battery voltage conditions cause the chip to enter a low-power sleep mode. Attempting to charge the battery pack wakes the chip. Provides one cell counting pin (CLCNT) IC solutions for three or four cell operation. Two-stage overcurrent controller and external current shunt to prevent over-discharged battery pack current. Internal timing circuitry charges an external capacitor to provide user programmable blanking time if the first overcurrent threshold level is exceeded. If the condition still exists at the end of the overcurrent blanking time, the external discharge FET is turned off for a period 17 times longer than the first blanking period, and then the discharge FET is turned on again. If at any time a second higher overcurrent multiuser exceeds the threshold for a programmable time, the discharge FET turns off and remains off for the same period as the first echelon turns off. The two-layer overcurrent protection scheme can charge capacitive loads while retaining effective short-circuit protection.