Not Recommended For New Design as of 18-Apr-2008
This highly integrated PWM controller provides several special enhancements designed to meet the low standby power needs of low-power SMPS. To minimize standby power consumption, the proprietary green-mode function provides off-time modulation to linearly decrease the switching frequency under light-load conditions. This green-mode function enables the power supply to meet even the strictest power conservation requirements. The BiCMOS fabrication process enables reducing the start-up current to 10µA and the operating current to 2.5mA. To further improve power conservation, a large start-up resistance can be used. Built-in synchronized slope compensation ensures the stability of peak current mode control. Proprietary internal compensation provides a constant output power limit over a universal AC input range (90VAC to 264VAC). Pulse-by-pulse current limiting ensures safe operation even during short-circuits. To protect the external power MOSFET from being damaged by supply over-voltage events, the SG6858’s output driver is clamped at 17V. SG6858 controllers can be used to improve the performance and reduce the production cost of power supplies and can replace linear and RCC-mode power adapters. It is available in 8-pin DIP and 6-pin SSOT-26 packages.