FAN6751MR

The highly integrated FAN6751 series of PWM controllers provides several features to enhance the performance of flyback converters.

To minimize standby power consumption, a proprietary green-mode function provides off-time modulation to linearly decrease the switching frequency at light-load conditions. To avoid acoustic-noise problems, the minimum PWM frequency is set above 18KHz. This green-mode function enables the power supply to meet international power conservation requirements. With the internal high-voltage startup circuitry, the power loss due to bleeding resistors is also eliminated. To further reduce power consumption, FAN6751 is manufactured using the BiCMOS process, which allows an operating current of only 4mA.

Built-in synchronized slope compensation achieves stable peak-current-mode control. The proprietary, external line compensation ensures constant output power limit over a wide AC input voltage range, from 90V_AC to 264V_AC.

FAN6751 provides many protection functions. In addition to cycle-by-cycle current limiting, the internal open-loop protection circuit ensures safety should an open-loop or output short-circuit failure occur. PWM output is disabled until V_DD drops below the UVLO lower limit, when the controller starts up again. As long as V_DD exceeds ~26V, the internal OVP circuit is triggered. FAN6751 is available in an 8-pin SOP package.