The LTC 1731-4.2 is a complete constant-current/constant-voltage linear charge controller for lithium-ion batteries. Nickel-cadmium (NiCd) and nickel-metal-hydride (NiMH) batteries can also be charged with constant current using external termination. The external sense resistor sets the charge current with 5% accuracy. An internal resistor divider and precision reference set the final float potential with 1% accuracy. The output float voltage is set internally to 4.2V.