Maker : Fairchild Semiconductor
Part No. : SG6846G

  Datasheet PDF : SG6846G.pdf
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Product Information

SG6846G — Highly Integrated Green-Mode PWM Controller www.DataSheet4U.com October 2008 SG6846G Highly Integrated Green-Mode PWM Controller Features Low Startup Current: 8µA Low Operating Current: 3.7mA Peak-Current-Mode Operation with Cycle-by-Cycle Current Limiting PWM Frequency Continuously Decreasing with Burst Mode at Light Loads VDD Over-Voltage Protection (OVP) AC Input Brownout Protection with Hysteresis Constant Output Power Limit (Full AC Input Range) Internal Latch Circuit for OVP, OTP, and OCP Two-Level OCP Delay: 110ms Programmable PWM Frequency with Frequency Hopping OCP Threshold is Half Peak Current Limit Feedback Open-Loop Protection with 110ms Delay Soft Startup Time: 5ms Description A highly integrated PWM controller, SG6846G 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 continuously decrease the switching frequency under light-load conditions. Under zero-load conditions, the power supply enters burst-mode, which completely shuts off PWM output. Output restarts just before the supply voltage drops below the UVLO lower limit. This green-mode function enables power supplies to meet international power conservation requirements. The SG6846G is designed for SMPS with surge-current output, incorporated with a two-level OCP function. Besides the cycle-by-cycle current limiting; if the switching current is higher than OCP threshold and lasts for 110ms, SG6846G shuts down immediately. SG6846G also integrates a frequency-hopping function internally, which helps reduce EMI emission of a power supply with minimum line filters. The built-in synchronized slope compensation provides proprietary internal compensation for constant output power limit over a universal AC input range. The gate output is clamped at 18V to protect the external MOSFET from over-voltage damage. Other protection functions include AC input brownout protection with hysteresis and VDD over-voltage protection. For over-temperature protection, an external NTC thermistor can be applied to sense the ambient temperature. When OCP, VDD OVP, or OTP are activated, an internal latch circuit latches off the controller. The latch resets when VDD supply is removed. SG6846G is available in an 8-pin SOP package. Applications General-purpose, switch-mode power supplies and flyback power converters, including: Power Adapters Open-Frame SMPS SMPS with Surge-Current Output, such as for Printers, Scanners, Motor Drivers Ordering Information Part Number SG6846GLSY Operating Temperature Range -40 to +105°C OCP Latch Yes Eco Status Green Package 8-Pin Small Outline Package (SOP) Packing Method Tape & Reel For Fairchild’s definition of “green” Eco Status, please visit: http://www.fairchildsemi.com/company/green/rohs_green.html. © 2008 Fairchild Semiconductor Corporation SG6846G • Rev. 1.0.0 www.fairchildsemi.com SG6846G — Highly Integrated Green-Mode PWM Controller Typical Application www.DataSheet4U.com L AC input EMI Filter + + VO+ N VO+ 7 3 VIN RI FB VDD GATE 8 SENSE 6 4 2 GND 1 RT 5 SG6846G Figure 1. Typical Application Block Diagram Ri 4 0.9V/0.7V VDD VIN 3 Over Power Compensation 1.18-0.08 XVIN Soft Driver 8 GATE VDD -TH-G VDD 7 UVLO Internal BIAS Q S R OSC Green Mode 6V 3R 16.5V/10.5V + 1R R 2 FB Latch Slope Compensation Blanking Circuit 6 SENSE 23.6V 1R Debounce OCP Delay 1R IRT RT 5 1.05V 1.15V 1 GND Figure 2. Block Diagram © 2008 Fairchild Semiconductor Corporation SG6846G • Rev. 1.0.0 www.fairchildsemi.com 2 SG6846G — Highly Integrated Green-Mode PWM Controller Marking Information www.DataSheet4U.com : Fairchild Logo Z: Plant Code X: Year Code Y: Week Code TT: Die Run Code F: L = OCP Latch T: Package Type, S = SOP P: Y = Green Compound M: Manufacturing Flow Code Figure 3. Top Mark Pin Configuration Figure 4. Pin Configuration Pin Definitions Pin # 1 2 ...

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