SG6846 Highly Integrated Green-Mode PWM Controller Features Description Low Startup Current: 8A PWM Frequency Continuously Decreasing with Burst Mode at Light Loads VDD Over-Voltage Protection (OVP) The highly integrated SG6846 series of PWM controllers 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. This completely shuts off PWM output. The output restarts just before the supply voltage drops below the under-voltage lockout (UVLO) lower limit. This green-mode function enables power supplies to meet international power conservation requirements easily. Very Few External Components Low Operating Current: 3.7mA Peak-Current Mode of Operation with Cycle-byCycle Current Limiting AC Input Brownout Protection with Hysteresis Constant Output-Power Limit (Full AC Input Range) Internal Latch Circuit for OVP, OTP, and OCP Two-level Over-Current Protection (OCP) with 96ms Delay Time Programmable Over-Temperature Protection (OTP) Applications General-purpose switch-mode power supplies and flyback power converters, including: Power Adapters The SG6846 is designed especially for switch-mode power supply (SMPS) with surge-current output. It is incorporated with a two-level OCP function. Besides the cycle-by-cycle current limiting, if the switching current is higher than 2/3 of the peak-current threshold for a delay time, OCP is activated such that the SG6846 is totally shut down. Other protection functions include: AC-input brownout protection with hysteresis and VDD OVP. For OTP, an external NTC thermistor can be applied to sense the ambient temperature. When OCP, VDD OVP, or OTP are activated, an internal latch circuit is used to latch off the controller. The latch resets when the VDD supply is removed. Other features of this controller include built-in synchronized slope compensation and proprietary internal compensation for constant output-power limit over universal-AC-input range. Also, the gate output is clamped at 18V to protect the external MOSFET from over-voltage damage. Open-Frame SMPS SMPS with Surge-Current Output, such as for Printers, Scanners, Motor Drivers The SG6846 series controllers are available in both 8pin dual in-line (DIP) and small outline (SOP) packages. Ordering Information Part Number SG6846LSZ Operating Temperature Range OTP Latch -20 to +85C Yes Package Packing Method RoHS 8-Pin SOP Tape & Reel Eco Status SG6846LSY -20 to +85C Yes Green 8-Pin SOP Tape & Reel SG6846LDZ -20 to +85C Yes RoHS 8-Pin DIP Tube SG6846LDY -20 to +85C Yes Green 8-Pin DIP Tube For Fairchild's definition of "green" Eco Status, please visit: http://www.fairchildsemi.com/company/green/rohs_green.html. (c) 2008 Fairchild Semiconductor Corporation SG6846 * Rev. 1.3.1 www.fairchildsemi.com SG6846 -- Highly Integrated Green-Mode PWM Controller November 2008 Figure 1. Typical Application Block Diagram SG6846 -- Highly Integrated Green-Mode PWM Controller Typical Application Figure 2. Block Diagram (c) 2008 Fairchild Semiconductor Corporation SG6846 * Rev. 1.3.1 www.fairchildsemi.com 2 F: L = OTP Latch SG6846FTP T: D = DIP, S = SOP P : Z = Lead Free + ROHS Compatible Null = Regular Package XXXXXXXXYWWV XXXXXXXX: Wafer Lot Y: Year; WW: Week V: Assembly Location Marking for SG6846LSZ (Pb-free) SG6846LDZ (Pb-free) Figure 3. Top Mark 1 : Fairchild logo Z: Plant Code SG6846 -- Highly Integrated Green-Mode PWM Controller Marking Information X: Year Code Y: Week Code TT: Die Run Code F: L = OCP Latch T: Package Type (D = DIP, S = SOP) P: Y = Green Package M: Manufacturing Flow Code Marking for SG6846LSY (Green-compound) SG6846LDY (Green-compound) Figure 4. Top Mark 2 (c) 2008 Fairchild Semiconductor Corporation SG6846 * Rev. 1.3.1 www.fairchildsemi.com 3 Figure 5. Pin Configuration Pin Definitions Pin # Name Function 1 GND Ground 2 FB Feedback 3 VIN Line-Voltage Detection 4 RI Reference Setting 5 RT Temperature Detection 6 SENSE Current Sense 7 VDD Power Supply 8 GATE Driver Output (c) 2008 Fairchild Semiconductor Corporation SG6846 * Rev. 1.3.1 Description Ground. The signal from the external compensation circuit is fed into this pin. The FB pin and the current-sense signal from Pin 6 determine the PWM duty cycle. Line-voltage detection. The line-voltage detection is used for brownout protection with hysteresis. Constant-output-power limit over universal-AC-input range is also achieved using the VIN signal. It is suggested to add low-pass filter to filter out line ripple on bulk capacitor. A resistor from the RI pin to ground generates a reference current source inside SG6846. This determines the switching frequency. Increasing the resistance reduces the switching frequency. Using a 26k resistor RI results in a 65KHz switching frequency. For OTP. An external negative temperature coefficient (NTC) thermistor is connected from this pin to the GND pin. The impedance of the NTC decreases at high temperatures. Once the voltage of the RT pin drops below a threshold, PWM output is disabled. Current sense. The sensed voltage is used for peak-current-mode control and cycle-by-cycle current limiting. If the switching current is higher than 2/3 of the peak-current threshold for longer than 96ms, OTP is activated. This two-level OCP feature is especially suitable for SMPS with surge current output. Power Supply. The internal protection circuit disables PWM output in response to VDD over voltage. The totem-pole output driver for the power MOSFET. A soft driving waveform is implemented for improved electromagnetic interference (EMI). SG6846 -- Highly Integrated Green-Mode PWM Controller Pin Configuration www.fairchildsemi.com 4 Stresses exceeding the absolute maximum ratings may damage the device. The device may not function or be operable above the recommended operating conditions and stressing the parts to these levels is not recommended. In addition, extended exposure to stresses above the recommended operating conditions may affect device reliability. The absolute maximum ratings are stress ratings only. All voltage values, except differential voltages, are given with respect to GND pin. Symbol Parameter VDD Supply Voltage VL Input Voltage to FB, SENSE, VIN, RT, RI Pins PD Power Dissipation RJC TJ TSTG TL ESD Thermal ResistanceJunction-to-Case) Min. Max. Unit 25 V -0.3 7.0 V SOP 400 DIP 800 SOP 41.2 DIP 67.1 mW C/W Operating Junction Temperature -40 +125 C Storage Temperature Range -65 +150 C +260 C Human Body Model, JESD22-A114 2.0 kV Machine Model, JESD22-A115A 200 V Lead Temperature, Wave Soldering, 10 Second Recommended Operating Conditions SG6846 -- Highly Integrated Green-Mode PWM Controller Absolute Maximum Ratings The Recommended Operating Conditions table defines the conditions for actual device operation. Recommended operating conditions are specified to ensure optimal performance to the datasheet specifications. Fairchild does not recommend exceeding them or designing to Absolute Maximum Ratings. Symbol TA Parameter Operating Ambient Temperature (c) 2008 Fairchild Semiconductor Corporation SG6846 * Rev. 1.3.1 Min. Max. Unit -20 +85 C www.fairchildsemi.com 5 VDD = 15V and TA = 25C unless otherwise noted. Symbol Parameter Conditions Min. Typ. Max. Unit 20 V VDD Section VDD-OP Continuously Operating Voltage VDD-ON Turn-On Threshold Voltage 15.5 16.5 17.5 V VDD-OFF Turn-Off Voltage 9.5 10.5 11.5 V VDD-TH-G Low-Threshold Voltage for VDD to Exit Green-OFF Mode VDD-OFF +1.25V VDD-LH Threshold Voltage for Latch-Off Release IDD-ST Startup Current VDD-ON - 0.16V IDD-OP Operating Supply Current GATE Open VDD-OVP VDD Over-Voltage Protection (Latch Off) tD-VDDOVP VDD OVP Debounce Time IDD-H 3 22.6 RI = 26k o VDD OVP Latch-Off Holding Current VDD = 5V, TA=27 C V 4 5 V 8 30 A 3.7 5.0 mA 23.6 24.6 V 100 s 45 A VIN Section VIN-OFF PWM Turn-Off Threshold Voltage VIN-ON PWM Turn-On Threshold Voltage 0.67 0.72 0.77 V VIN-OFF +0.20 V 1/4.2 V/V Feedback Input Section AV Input-Voltage to Current-Sense Attenuation ZFB Input Impedance VFBO FB-Pin Open Voltage 4.0 5.5 7.0 SG6846 -- Highly Integrated Green-Mode PWM Controller Electrical Characteristics k 6.2 V k Current Sense Section ZSENSE Input Impedance 12 tPD Delay to Output 100 tLEB Leading-Edge Blanking Time 360 200 ns ns VSTH1V Threshold Voltage for Current Limit VIN = 1V, RI = 26k 0.78 0.83 0.88 V VSTH3V Threshold Voltage for Current Limit VIN = 3V, RI = 26k 0.65 0.70 0.75 V VSTH1V-2/3 OCP Threshold Voltage for Current Limit VIN = 1V, RI = 26k 0.56 0.61 0.66 V VSTH3V-2/3 OCP Threshold Voltage for Current Limit VIN = 3V, RI = 26k 0.46 0.51 0.56 V Delay Time for OTP RI = 26k 82 96 110 ms tD-OCP Continued on following page... (c) 2008 Fairchild Semiconductor Corporation SG6846 * Rev. 1.3.1 www.fairchildsemi.com 6 VDD = 15V and TA = 25C unless otherwise noted. Symbol Parameter Conditions Min. Typ. Max. Unit Oscillator Section fOSC Normal PWM Frequency RI = 26k 60 65 70 KHz fOSC-G Green-Mode Minimum Frequency RI = 26k 18.0 22.5 25.0 KHz VFB-N FB-Pin Threshold for the Beginning of Green Mode 2.1 V VFB-G Green-OFF-Mode Voltage at FB Pin 1.6 V 85 Hz/mV SG Slope for Green-Mode Modulation RI = 26k fDV Frequency Variation vs. VDD Deviation VDD = 11.5V to 20V fDT Frequency Variation vs. Temperature Deviation TA = -20 to 85C 1.5 5 % 5.0 % Continued on following page... Frequency SG6846 -- Highly Integrated Green-Mode PWM Controller Electrical Characteristics (Continued) PW M Frequency f OSC : 65KHz fOSC -GREEN : 22 .5KHz fOSC -OFF : 0Hz VFB -G V FB -N VFB Figure 6. PWM Frequency (c) 2008 Fairchild Semiconductor Corporation SG6846 * Rev. 1.3.1 www.fairchildsemi.com 7 VDD = 15V and TA = 25C unless otherwise noted. Symbol Parameter Conditions Min. Typ. Max. Unit 80 85 90 % 1.5 V PWM Output Section DCYMAX Maximum Duty Cycle VOL Output Voltage Low VDD = 15V, IOUT = 50mA VOH Output Voltage High VDD = 12V, IOUT = 50mA tr Rising Time VDD = 15V, GATE = 1nF 350 ns tf Falling Time VDD = 15V, GATE = 1nF 50 ns Gate Output Clamping Voltage VDD = 20V 18 V VCLAMP 8 V OTP Section IRT VRTTH tDOTP-LATCH VRT-RLS Output Current of RT Pin RI = 26k Threshold Voltage for OTP Over-Temperature Latch-Off Debounce 64 70 76 A 1.015 1.065 1.115 V RI = 26k OTP Release Voltage (for Non-Latch-Off Version) 100 s VRTTH + 0.1 V RI Section RINOR RI Operating Range RIMAX Maximum RI Value for Protection 216 k RIMIN Minimum RI Value for Protection 6 k (c) 2008 Fairchild Semiconductor Corporation SG6846 * Rev. 1.3.1 15.5 36.0 SG6846 -- Highly Integrated Green-Mode PWM Controller Electrical Characteristics (Continued) k www.fairchildsemi.com 8 SG6846 -- Highly Integrated Green-Mode PWM Controller Typical Performance Characteristics 11.5 17.5 11.1 VTH -OFF (V) VTH -ON (V) 11.3 17.0 16.5 16.0 10.9 10.7 10.5 10.3 10.1 9.9 9.7 15.5 -40 -25 -10 5 20 35 50 65 80 95 110 9.5 125 -40 -25 -10 5 Temperature (C)) 20 15.500 16 IDD -ST (A) 16.000 15.000 14.500 50 65 80 95 110 125 12 8 4 14.000 0 13.500 -40 -25 -10 5 20 35 50 65 80 95 110 5 125 7 9 11 13 15 17 19 VDD (V) Temperature (C) Figure 9. Startup Current vs. Temperature Figure 10. Startup Current vs. VDD Voltage 1. 000 1.000 0. 900 0.900 0. 800 0.800 VIN-ON (V) V IN-OFF (V) 35 Figure 8. Minimum Operating Voltage vs. Temperature Figure 7. Startup Threshold vs. Temperature IDD -ST (A) 20 Temperature (C) 0. 700 0. 600 0.700 0.600 0.500 0. 500 0. 400 0.400 -40 -25 -10 5 20 35 50 65 80 95 110 125 -25 -10 5 20 35 50 65 80 95 110 125 Temperature (C) Te m perature (C)) Figure 11. PWM Turn-Off Threshold Voltage vs. Temperature (c) 2008 Fairchild Semiconductor Corporation SG6846 * Rev. 1.3.1 -40 Figure 12. PWM Turn-On Threshold Voltage vs. Temperature www.fairchildsemi.com 9 PWM Frequency (KHz) 65.300 65.200 fOSC (KHz) 65.100 65.000 64.900 64.800 64.700 64.600 -40 -25 -10 5 20 35 50 65 80 95 110 60 40 20 0 1.5 125 1.6 1.7 1.8 2 2.1 2.2 2.3 V FB (V) Temperature (C) Figure 13. PWM Frequency vs. Temperature Figure 14. PWM Frequency vs. FB Voltage (RI=26k) 1 1 0.8 0.8 VTH -O (V) VTH -P (V) 1.9 0.6 0.4 0.2 0.6 0.4 0.2 0 SG6846 -- Highly Integrated Green-Mode PWM Controller Typical Performance Characteristics (Continued) 0 1 1.5 2 2.5 3 1 1.5 2 VIN (V) 2.5 3 VIN (V) Figure 15. Current-Limit Threshold vs. VIN Voltage Figure 16. 2/3 Current-Limit Threshold vs. VIN Voltage 1.115 78.000 77.000 VOTP-O FF (V) 1.095 IRT (A) 76.000 75.000 74.000 73.000 72.000 1.075 1.055 1.035 71.000 70.000 -40 -25 -10 5 20 35 50 65 80 95 110 125 Temperature (C) -40 -25 -10 5 20 35 50 65 80 95 110 125 Temperature (C) Figure 17. Output Current of RT Pin (IRT) vs. Temperature (c) 2008 Fairchild Semiconductor Corporation SG6846 * Rev. 1.3.1 1.015 Figure 18. OTP Threshold Voltage vs. Temperature www.fairchildsemi.com 10 Startup Operation Two-Level Over-Current Protection (OCP) The turn-on/turn-off thresholds are fixed internally at 16.5V/10.5V. To enable the SG6846 during startup, the hold-up capacitor must first be charged to 16.5V through the startup resistor. Cycle-by-cycle current limiting shuts down the PWM immediately when the switching current is over the peak-current threshold. Additionally, when the switching current is higher than 2/3 of the peak-current threshold, the internal counter starts counting up. When the switching current is lower than 2/3 of the peak current threshold, the internal counter counts down. When the total accumulated counting time is more than about 96ms (RI = 26k), the controller is latched off. The hold-up capacitor continues to supply VDD before energy can be delivered from the auxiliary winding of the main transformer. The VDD must not drop below 10.5V during this startup process. This UVLO hysteresis window ensures that the hold-up capacitor can adequately supply VDD during startup. The two-level OCP protection and up/down counter are especially designed for SMPS with surge current output such as those for printers, scanners, and motor drivers. The typical startup current is only 8A. This allows a high resistance, low-wattage startup resistor to be used to minimize power loss. A 1.5M/0.25W, startup resistor and a 10F/25V VDD hold-up capacitor is sufficient for a universal input range. Constant-Output-Power Limit For constant-output-power limit over universal inputvoltage range, the peak-current threshold is adjusted by the voltage of the VIN pin. Since the VIN pin is connected to the rectified AC-input line voltage through the resistive divider, a higher line voltage generates a higher VIN voltage. The threshold voltage decreases as the VIN voltage increases, making the maximum output power at high-line input voltage equal to that at low-line input. The required operating current has been reduced to 3.7mA. This enables higher efficiency and reduces the VDD hold-up capacitance requirement. Green-Mode Operation Power supplies using the SG6846 can easily meet even the most restrictive international regulations regarding standby power consumption. The proprietary green-mode function provides off-time modulation to continuously decrease the switching frequency under light-load conditions. Maximum on time is limited to provide protection against abnormal conditions. To further reduce power consumption under zero-load condition, the PWM oscillator is completely turned off and the power supply enters burst-mode. After the PWM oscillator is turned off, the IC's supply voltage VDD drops gradually. Before the VDD voltage drops below the UVLO threshold, the PWM oscillator is turned on again. This green-mode function dramatically reduces power consumption under light-load and zero-load conditions. Brownout Protection Since the VIN pin is connected through a resistive divider to the rectified AC input line voltage, it can also be used for brownout protection. If the VIN voltage is less than 0.72V, the PWM output is shut off. If the VIN voltage is over 0.92V, the PWM output is turned on again. The hysteresis window for ON/OFF is around 0.2V. VDD Over-Voltage Protection (OVP) VDD OVP is built in to prevent damage. If VDD is over 23.6V, SG6846 is latched off. Over-Temperature Protection (OTP) Oscillator Operation An external NTC thermistor can be connected from the RT pin to GND. The impedance of the NTC decreases at high temperatures. When the voltage of the RT pin drops below 1.05V, the SG6846 is turned off. For protection-mode options, see Ordering Information. A resistor connected from the RI pin to GND generates a reference-current source inside the SG6846. This current is used to determine the PWM frequency. Increasing the resistance decreases the amplitude of the current source and reduces the PWM frequency. Using a 26k resistor RI results in a corresponding 65KHz switching frequency. The relationship between RI and the switching frequency is: fPWM (KHz) = 1690 RI (k) SG6846 -- Highly Integrated Green-Mode PWM Controller Operation Description (1) If an open circuit or short circuit to ground occurs at the RI pin, the internal protection circuit immediately shuts down the controller. (c) 2008 Fairchild Semiconductor Corporation SG6846 * Rev. 1.3.1 www.fairchildsemi.com 11 Noise Immunity Noise from the current sense or the control signal may cause significant pulse-width jitter, particularly in continuous-conduction mode. Slope compensation helps alleviate this problem. Good placement and layout practices should be followed. Avoid long PCB traces and component leads. Compensation and filter components should be located near the SG6846. Figure 19. Current Sense R-C Filter (c) 2008 Fairchild Semiconductor Corporation SG6846 * Rev. 1.3.1 SG6846 -- Highly Integrated Green-Mode PWM Controller Operation Description (Continued) www.fairchildsemi.com 12 RT1 R16 D4 2 4 1 5 2 32V C13 11 C11 12 2 P16V P16V L2 1 2 2 R11 C5 3 C17+ C14 + 16V 16V C15 + 1 1 C3 2 R17 2 + 1 9 3 2 + 32V + 2 1 21 2 1 R4 7 1 1 2 D3 L4 C12 + 10 D2 D1 2 2 6 R9 R3 C16+ 3 R12 C4 C2 3 2 R2 R1 13 1 + R8 1 P7 P32V P32V L1 1 2 CX2 4 3 1 P2 TX1 1 VZ1 LF1 CY2 BD1 1 CX1LF2 3 4 2 CY1 1 F1 t P1 2 U1 FB GATE Q1 R13 8 1 2 GND 3 1 2 FB VDD VIN SENSE 7 L3 R6 6 1 2 3 1 D5 + 1 C1 R5 4 RI RT 5 R10 C6 R14 NTC1 R7 P16V P16V 1 4 R15 FB P16V FB C7 K R18 P32V R19 R20 2 3 U2 P32V P16V C9 R R21 A U3 Figure 20. Application Circuit for 32V / 16V Output SG6846 -- Highly Integrated Green-Mode PWM Controller Reference Circuit BOM Part No. Value Part No. Value Part No. Value R1, R2, R3, R4 R8, R9 470K +/-5% C4 S1M +/-1% C10,C11 103 P 630V D3 FR103 1.0A 200V 102 P 1KV BD1 DBL406G R5 16K2 +/-1% C6,C7 102 P 50V D4 BYT28-300 R15 R13 1K5 +/-5% C9 222 P 50V D5 BYV32-150 10 +/-5% C14,C17 470 25V F1 250V4A QUICK R18 4K7 +/-5% C15 220 25V L1,L2 1.8H R21 15K +/-1% C13,C16 220 50V L4 10H R7 27K +/-5% C2 150 400V U3 TL431 +/-1% R6 330 +/-1% C1 4.7 50V U1 SG 6846 R19 102K +/-1% C3 10 50V U2 PC817 R14 022 +/-5% CX1 X1 0.47 275V Q1 7NB60 R16, R17 1W 20 +/-5% C8 Y2 222P 250V TX1 EI-33 R11 20K +/-5% C5 100 50V RT1 SCK053 R12 100K +/-5% CX2 X2 0.1F 275V VZ1 14 470V R20 887K +/-1% D1 1N4148 R22 10K +/-1% D2 BYV95C (c) 2008 Fairchild Semiconductor Corporation SG6846 * Rev. 1.3.1 www.fairchildsemi.com 13 SG6846 -- Highly Integrated Green-Mode PWM Controller Physical Dimensions 9.83 9.00 6.67 6.096 8.255 7.61 3.683 3.20 5.08 MAX 7.62 0.33 MIN 3.60 3.00 (0.56) 2.54 0.56 0.355 0.356 0.20 9.957 7.87 1.65 1.27 7.62 NOTES: UNLESS OTHERWISE SPECIFIED A) THIS PACKAGE CONFORMS TO JEDEC MS-001 VARIATION BA B) ALL DIMENSIONS ARE IN MILLIMETERS. C) DIMENSIONS ARE EXCLUSIVE OF BURRS, MOLD FLASH, AND TIE BAR EXTRUSIONS. D) DIMENSIONS AND TOLERANCES PER ASME Y14.5M-1994 E) DRAWING FILENAME AND REVSION: MKT-N08FREV2. Figure 21. 8-Pin Dual In-Line Package (DIP) Package drawings are provided as a service to customers considering Fairchild components. Drawings may change in any manner without notice. Please note the revision and/or date on the drawing and contact a Fairchild Semiconductor representative to verify or obtain the most recent revision. Package specifications do not expand the terms of Fairchild's worldwide terms and conditions, specifically the warranty therein, which covers Fairchild products. Always visit Fairchild Semiconductor's online packaging area for the most recent package drawings: http://www.fairchildsemi.com/packaging/. (c) 2008 Fairchild Semiconductor Corporation SG6846 * Rev. 1.3.1 www.fairchildsemi.com 14 5.00 4.80 A 0.65 3.81 5 8 B 6.20 5.80 PIN ONE INDICATOR 1.75 4.00 3.80 1 5.60 4 1.27 (0.33) 0.25 M 1.27 C B A LAND PATTERN RECOMMENDATION 0.25 0.10 SEE DETAIL A 1.75 MAX R0.10 0.10 0.51 0.33 0.50 x 45 0.25 C OPTION A - BEVEL EDGE GAGE PLANE R0.10 8 0 0.90 0.406 0.25 0.19 C SG6846 -- Highly Integrated Green-Mode PWM Controller Physical Dimensions OPTION B - NO BEVEL EDGE 0.36 NOTES: UNLESS OTHERWISE SPECIFIED A) THIS PACKAGE CONFORMS TO JEDEC MS-012, VARIATION AA, ISSUE C, B) ALL DIMENSIONS ARE IN MILLIMETERS. C) DIMENSIONS DO NOT INCLUDE MOLD FLASH OR BURRS. D) LANDPATTERN STANDARD: SOIC127P600X175-8M. E) DRAWING FILENAME: M08AREV13 SEATING PLANE (1.04) DETAIL A SCALE: 2:1 Figure 22. 8-Pin Small Outline Package (SOP) Package drawings are provided as a service to customers considering Fairchild components. Drawings may change in any manner without notice. Please note the revision and/or date on the drawing and contact a Fairchild Semiconductor representative to verify or obtain the most recent revision. Package specifications do not expand the terms of Fairchild's worldwide terms and conditions, specifically the warranty therein, which covers Fairchild products. Always visit Fairchild Semiconductor's online packaging area for the most recent package drawings: http://www.fairchildsemi.com/packaging/. (c) 2008 Fairchild Semiconductor Corporation SG6846 * Rev. 1.3.1 www.fairchildsemi.com 15 SG6846 -- Highly Integrated Green-Mode PWM Controller (c) 2008 Fairchild Semiconductor Corporation SG6846 * Rev. 1.3.1 www.fairchildsemi.com 16