‧Low operating current (4mA)
‧Linearly decreasing PWM frequency to 22kHz
‧Frequency hopping to reduce EMI emission
‧Cycle-by-cycle current limiting
‧Synchronized slope compensation
‧ GATE output maximum voltage clamp (18V)
‧ VDD over voltage clamping
‧ VDD under-voltage lockout (UVLO)
‧ Internal open-loop protection
‧ Constant power limit (full AC input range)
‧Highly-Integrated Green Mode PWM Controller
‧SG6741SZ 8-Pin SOP(Lead Free)
‧Open Frame SMPS
【文字介紹】The highly integrated SG6741 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 problem, the minimum PWM frequency set above 22KHz. This green-mode function enables the power supply to easily 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, SG6741 is manufactured by using the BiCMOS process. This allows the operating current only 4mA.
SG6741 integrates frequency-hopping function internally. The frequency jittering function helps reduce EMI emission of a power supply with minimum line filters. Also, its 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 90VAC to 264VAC.
SG6741 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 occur. PWM output is disabled till VDD drops below the UVLO lower limit. Then, the controller starts up again. As long as VDD exceeds about 26V, the internal OVP circuit is triggered.