A power management controller circuit with switched capacitor mode down regulator and battery charger block for semi-active RFID tags was proposed and fabricated. The main purposes of the proposed switched capacitor mode down regulator and battery charger block are to reduce standby current and to provide a self-controlled thin film battery charger by detecting the received RF power, respectively. Fabricated chip area is $360,000{mu}m^2$ and measured standby current was about $1.3{mu}A$. To further reduction of standby current, a wake-up circuit has to be included in the power management controller.