Low Cost Green-Mode PWM Controller - Fairchild Semiconductor
Description
SG6859A — Low Cost, Green-Mode PWM Controller for Flyback Converters
SG6859A
Low-Cost, Green-Mode PWM Controller for Flyback Converters
Features
Green-Mode PWM Supports the “Blue Angel” Standard Low Startup Current: 9 μA Low Operating Current: 3 mA 300 mA Driving Capability Leading-Edge Blanking Constant Output Power Limit Universal Input Built-in Synchronized Slope Compensation Current-Mode Operation Cycle-by-cycle Current Limiting Under-Voltage Lockout (UVLO) Programmable PWM Frequency with Frequency
Hopping
VDD Over-Voltage Protection (Auto Restart) Gate Output Voltage Clamped at 17 V Low Cost Few External Components Required Small SOT23-6L Package
Description
This highly integrated PWM controller provides several 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 startup current to 9 μA and the operating current to 3 mA.
To further improve power conservation, a large startup 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 (90 VAC to 264 VAC).
Pulse-by-pulse current limiting ensures safe operation during shortcircuits.
To protect the external power MOSFET from damage by supply over voltage, the SG6859A’s output driver is clamped at 17 V.
SG6859A controllers can be used to improve the performance and reduce the production cost of power supplies.
The best choice for replacing linear and RCC-mode power adapters, the SG6859A is available in 8-pin DIP and 6-pin SOT23-6L packages.
Applications
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