SG6741A

The highly integrated SG6741A 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 start-up circuitry, the power loss due to bleeding resistors is eliminated.To further reduce power consumption, SG6741A is manufactured using the BiCMOS process, which allows operating current as low as 4mA.

SG6741A integrates a frequency-hopping function that helps reduce EMI emission of a power supply with minimum line filters.A built-in synchronized slope compensation achieves stable peak-current-mode control.The proprietary internal line compensation ensures constant output power limit over a wide AC input voltages, from 90V_AC to 264V_AC.

SG6741A provides many protection functions. In addition to cycle-by-cycle current limiting,the internal open-loop protection circuit ensures safety when an open-loop or output short-circuit failure occurs.PWM output is disabled until V_DD drops below the UVLO lower limit, when the controller starts again.As long as V_DD exceeds ~26V, the internal OVP circuit is triggered.

SG6741A is available in an 8-pin SOP package.