General Description
The MAX1665 provides protection against overvoltage, undervoltage, overcharge current, and overdischarge current for 2-cell to 4-cell lithium-ion (Li+) battery packs. Very low operating current ensures that cells are not overdischarged during long storage periods.
The MAX1665 controls two external N-channel MOSFETs to limit the charge and discharge voltages. Charging is allowed when the per-cell voltage is below +4.3V. When the voltage on any cell rises above +4.3V (overvoltage limit), the MAX1665 turns off the charge MOSFET. This safety feature prevents overcharge of any cell within the battery pack.
Discharge is allowed when the per-cell voltage is above +2.5V (undervoltage limit). If the voltage across any cell falls below +2.5V, the MAX1665 turns off the discharge MOSFET. This safety feature prevents overdischarge of any cell within the battery pack.
Charging and discharging are allowed if the voltage between PKN and BN is less than 250mV. This safety feature prevents excessive pack current.

Features
♦ Complete Protection Against:
   Cell Overvoltage
   Cell Undervoltage
♦ Pack Protection for Excessive Charge and Discharge
♦ Very Low Supply Current: 16µA typ
♦ Low Standby Current: 1µA max
♦ Matched Cell Input Bias Current (<500pA) Preserves Cell Balance

Applications
   Lithium-Ion Battery Packs