A charging controller includes a control node having a control voltage generated thereon for controlling a first current to a charged device and a second current to a reference device. Feedback loops are formed with amplifiers and a pull-up current source and control transistors, or with amplifiers and transfer transistors, for maintaining the second current at a constant current level during a constant current mode and for maintaining a voltage of the charged device at a constant voltage level during a constant voltage mode. Use of a pull-down current source at the control node is avoided for preventing damage to the charged device.