The CN3767 is a PWM switch-mode battery charger controller for 12V lead-acid battery in a small package using few external components. The CN3767 is specially designed for charging 12V lead-acid battery with trickle charge, constant current charge, over-charge and float charge mode. In over-charge and float charge mode, the regulation voltage is internally set. The constant charge current is programmable with a single sense resistor. The CN3767 can be powered by solar panel with MPPT function. Deeply discharged batteries are automatically trickle charged at 17.5% of the programmed constant charge current until the cell voltage exceeds 75% of the regulation voltage in over-charge mode. The over-charge is terminated once the charging current drops to 38% of the constant charge current, then CN3767 will enter into float charge mode. A new charge cycle automatically restarts if the battery voltage falls below 83.95% of the over-charge voltage in float-charge mode. CN3767 will automatically enter sleep mode when input voltage is lower than battery voltage. Other features include under-voltage lockout and status indication, etc. CN3767 is available in a space-saving 10-pin SSOP package.