Demonstration circuit DC674B is a complete Fast Battery Charger capable of charging 3, 4, 6 or 10 series connected NiMH or NiCd cells. Other cell counts can also be charged (up to 16 cells) by installing an appropriate resistor on the board. The power portion of the circuit consists of a 550kHz synchronous step-down constant current source which provides 2A of charge current. Other charge currents can be selected by changing the sense resistor value, and for higher charge current (2 to 4A), the PC board has a dual layout for the top switch to allow a larger FET to be used. A PowerPath™ FET is also included that provides a low voltage drop path between the battery and an external system load when the input power is removed Charge termination includes -ΔV, ΔT/Δt, peak voltage and a safety timer.