This highly integrated PWM controller, FAN100, provides several features to enhance the performance of low-power flyback converters. The proprietary topology enables simplified circuit design for battery charger applications. A low-cost, smaller, and lighter charger results when compared to a conventional design or a linear transformer. The startup current is only 10μA, which allows use of large startup resistance for further power saving. To minimize the standby power consumption, the proprietary green-mode function provides off-time modulation to linearly decrease PWM frequency under light-load conditions. This green-mode function assists the power supply meeting the power conservation requirements. Using FAN100, a charger can be implemented with fewest external components and minimized cost. A typical output CV/CC characteristic envelope is shown in Figure 1.