Overview: Preliminary Specification Highly-Integrated Green-Mode PWM Controller www.DataSheet4U.com SG6842
zero-load conditions, the power supply enters burst-mode. This completely shuts off PWM output. Then, the output restarts just before the supply voltage, VDD, drops below the UVLO voltage. This green-mode function enables the power supply to easily meet international power conservation requirements. For improved power conversion efficiency, the SG6842 series is manufactured using the BiCMOS process. This allows the start-up current to be reduced to 20uA, and the operating current to be reduced to 4mA. For even higher power conversion efficiency, a large start-up resistance can be used. Built-in synchronized slope compensation ensures the stability of peak current mode control. Proprietary internal compensation ensures constant output power limiting over a universal range of AC input voltages, from 90VAC to 264VAC. SG6842 controllers provide many protection functions. Pulse-by-pulse current limiting ensures a constant output current, even when short circuits occur. Should an open circuit failure occur in the feedback loop, the internal protection circuit will disable PWM output. PWM output will be disabled as long as VDD remains higher than 26V. The gate output is clamped at 18V to protect the power MOS from over-voltage damage. An external NTC thermistor can be applied to sense the ambient temperature for over temperature protection. When either over temperature conditions or VDD over voltage faults are detected, an internal latch circuit is used to latch-off the controller. The latch will reset when the temperature cools off sufficiently, or when the VDD power supply is disabled. SG6842 series controllers are available in both 8-pin DIP and SO packages.
