Battery Protectors Prevent Voltage & Charge Faults

Protection against over-voltage, under-voltage, cell shorts, overcharge, and over-discharge currents for lithium-ion battery packs with 2, 3, or 4 series cells is provided with the MAX1665. On-chip power MOSFET drivers control external N-channel MOSFETs to disconnect the cells from the pack terminals when a fault condition occurs. Designing safety circuitry is simplified by selecting the power MOSFETs and connecting the Li+ cells. The chip has a ±1% accurate, factory-trimmed, 4.25V over-voltage threshold limit, and there is no current-sense resistor. It connects battery voltages as high as 20V without an external linear regulator. The device consumes 15µA in operation and less than 1µA in shutdown. Three versions are currently available and include the MAX1665S for two series cells; the MAX1665V for three series cells; and the MAX1665X for four series cells. Pricing starts at $1.55 each/1000 for the four-cell protectors.