A constant-current/constant-voltage linear charger for single-cell lithium-ion (li-ion) can be constructed using only a tiny battery charger controller chip EUP8054 and a few passive components. This tiny integrated circuit chip is suitable for various portable devices. This controller chip is also compatible with USB power specification, ideal for charging the battery when the device is plugged to USB port. This is the figure of the circuit;
External sense resistor is not needed since the MOSFET internal architecture has accommodated this function. During high power operation or high temperature, a thermal feedback regulates the charge current to limit the die temperature. The charge voltage is fixed at 4.2V, and the charge current is adjustable via an external resistor. The controller chip automatically terminate the charging cycle when the charging current drops to 1/10th of nominal programmed value after the final float voltage is reached. The controller automatically enter low current state when the input supply is removed, draw less than 2uA current from the battery.
External sense resistor is not needed since the MOSFET internal architecture has accommodated this function. During high power operation or high temperature, a thermal feedback regulates the charge current to limit the die temperature. The charge voltage is fixed at 4.2V, and the charge current is adjustable via an external resistor. The controller chip automatically terminate the charging cycle when the charging current drops to 1/10th of nominal programmed value after the final float voltage is reached. The controller automatically enter low current state when the input supply is removed, draw less than 2uA current from the battery.
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