Maker : System General
Part No. : SG6849

  Datasheet PDF : SG6849.pdf
  Cross Reference : SG6849 Cross Reference
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Product Information

www.DataSheet4U.com Product Specification Low-Power Green-Mode PWM Flyback Power Controller without Secondary Feedback SG6849 FEATURES Linearly Decreasing PWM Frequency Green-Mode under Light-Load and Zero-Load Conditions Constant Voltage (CV) and Constant Current (CC) No Secondary Feedback Low Startup Current (5uA) Low Operating Current (3.6mA) Leading-Edge Blanking Constant Power Limit Universal AC Input Range Synchronized Slope Compensation 150°C OTP Sensor with Hysteresis VDD Over Voltage Clamping Cycle-by-Cycle Current Limiting Under Voltage Lockout (UVLO) Fixed PWM Frequency (65kHz/100kHz) Gate Output Maximum Voltage Clamped at 16.7V Small SOT-26 Package DESCRIPTION This highly integrated PWM controller provides several features to enhance the performance of low power flyback converters. To minimize standby power consumption, the proprietary green-mode function provides off-time modulation to linearly decrease the switching frequency under light-load and zero-load conditions. This green-mode function enables the power supply to easily meet international power conservation requirements. The supply voltage VDD is also used for feedback compensation, to regulate the output voltage without requiring a conventional TL431 and a photo-coupler. Another advantage of the SG6849 is that the typical startup current is only 5uA, while the typical operating current can be as low as 3.6mA. A large startup resistance could be used to achieve even higher power conversion efficiency. Built-in synchronized slope compensation maintains 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.The SG6849 provides many protection functions. Pulse-by-pulse current limiting ensures a constant output current, even if a short circuit occurs. Also, the internal protection circuit will disable PWM output, if VDD exceeds 22.7V. The gate output is clamped at 16.7V to protect the power MOS from over-voltage damage. The built-in over temperature protection (OTP) function will shutdown the controller at 150°C with a 20°C hysteresis. The SG6849 is designed to provide a low-cost total solution for flyback converters. It is available in a small footprint, 6-pin, SOT-26 package. APPLICATIONS Low-power flyback power converters, such as Battery chargers for cellular phones, cordless phones, PDAs, digital cameras, and power tools. Power adapters for ink jet printers, video game consoles, and portable audio players. Open-frame SMPS for TV/DVD standby and other auxiliary supplies, home appliances, consumer electronics, and PC 5V standby-power. Replacements for linear transformers and RCC SMPS. TYPICAL IC APPLICATION V IN R IN D1 VDD G ATE DO CO W AU X VO Q1 C IN SE NSE GN D RS © System General Corp. Version 1.0(IRO33.0002.B3) -1- www.sg.com.tw Dec.29, 2003 Product Specification Low-Power Green-Mode PWM Flyback Power Controller without Secondary Feedback SG6849 MARKING INFORMATION PIN CONFIGURATION SOT-26 M: Mask Version MXYWW X: B= SG6849-65T C= SG6849-100T Y: Year 1 WW: Work Week GND FB NC 1 2 3 6 5 4 GATE VDD SENSE 8 ZZZ: 65 or 100 DIP-8 SG6849-ZZZD XXXXXXXYYWWV XXXXXXX: Wafer Lot YY: Year WW: Week V: Assembly Location GATE VDD NC SENSE 1 2 3 4 8 7 6 5 GND FB NC NC 1 ORDERING INFORMATION Part Number SG6849-65T SG6849-100T SG6849-65D SG6849-100D PWM Frequency 65kHz 100kHz 65kHz 100kHz Package 6-Pin SOT-26 6-Pin SOT-26 8-pin DIP-8 8-pin DIP-8 PIN DESCRIPTIONS Name GATE VDD NC SENSE NC NC FB GND Pin No. Type DIP-8 SOT-26 1 2 3 4 5 6 7 8 6 5 NA 4 3 NA 2 1 Supply Function Power supply. NC pin. Current sense. It senses the voltage across a sensed resistor. To provide over-current Driver Output The totem-pole output driver to drive the power MOSFET. Analog Input protection, PWM output is disabled if the voltage exceeds an internal threshold. This pin also provides current information for current-mode con...

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