Design of a multi-mode and high-stability linear charger for Lithium-ion batteries

In this paper, a monolithic linear charger for single-cell Lithium-ion batteries is presented. It is capable of operating within USB power specifications and adopts multiple charging modes (constant-current and constant-voltage). Due to novel constant-current and constant-voltage charging circuits, it achieves high stability and high accuracy charging voltage. In addition, an internal thermal feedback loop reduces the programmed charging current if the die temperature attempts to rise above a preset value of approximately 120□. The chip is implemented in a CSMC 0.5um CMOS mixed-signal process, experimental results shows the charging current of constant-current mode is 497mA and the final voltage of the battery after is 4.191V.