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| Product Specification Low Cost Green-Mode PWM Controller for Flyback Converters SG6859 FEATURES Green-Mode PWM Supports the "Blue Angel" Standard Low Start-up Current (9uA) Low Operating Current (3mA) 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 17V Low Cost Few External Components Required Small SOT-26 and Dip 8 Packages DESCRIPTION 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 easily meet even the strictest power conservation requirements. The BiCMOS fabrication process enables reducing the start-up current to 9uA, and the operating current to 3mA. 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, the SG6859's output driver is clamped at 17V. SG6859 controllers can be used to improve the performance and reduce the production cost of power supplies. The SG6859 is the best choice for replacing linear and RCC-mode power adapters. It is available in 8-pin DIP and 6-pin SOT-26 packages. APPLICATIONS General-purpose switching mode power supplies and 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, and consumer electronics Replacements for linear transformers and RCC SMPS PC 5V standby power. TYPICAL APPLICATION SG6859 (c) System General Corp. Version 1.2.1(IAO33.0067.B2) -1- www.sg.com.tw * www.fairchildsemi.com September 28,2007 Product Specification Low Cost Green-Mode PWM Controller for Flyback Converters SG6859 PIN CONFIGURATION SOT-26 GND FB RI DIP-8 GATE VDD SENSE MARKING DIAGRAMS AAJ: SG6859 M: Mask Version W: Week code A~Z=W1~W26 A~Z=W27~W52 : Lead Free Package AAJMW SG6859TP XXXXXXXXYWWV T: D=DIP P: Z =Lead Free Null=Regular Package XXXXXXXX: Wafer Lot Y: Year; WW: Week V: Assembly Location GATE VDD NC SENSE GND FB NC RI ORDERING INFORMATION Part Number SG6859TZ SG6859DZ Pb-Free Package 6-Pin SOT-26 8-Pin DIP-8 PIN DESCRIPTIONS Name GATE VDD NC Pin No. DIP-8(SOT-26) 1 / (6) 2 / (5) 3 Type Driver Output Supply Function The totem-pole output driver for driving the power MOSFET. Power supply. NC pin. Current sense. This pin senses the voltage across a resistor. When the voltage reaches the internal threshold, PWM output is disabled. This activates over-current protection. This pin also provides current amplitude information for current-mode control. A resistor connected from the RI pin to ground will generate a constant current source for the SG6859. This current is used to charge an internal capacitor, to determine the switching frequency. Increasing the resistance will reduce the amplitude of the current source and reduce the switching frequency. A 95k resistor Ri results in a 50uA constant current Ii and a 70kHz switching frequency. NC pin. Feedback. The FB pin provides the output voltage regulation signal. It provides feedback to the internal PWM comparator, so that the PWM comparator can control the duty cycle. Ground. SENSE 4 / (4) Analog Input RI 5 / (3) Analog Input/Output NC FB GND 6 7 / (2) 8 / (1) Analog Input Supply (c) System General Corp. Version 1.2.1(IAO33.0067.B2) -2- www.sg.com.tw * www.fairchildsemi.com September 28, 2007 Product Specification Low Cost Green-Mode PWM Controller for Flyback Converters SG6859 BLOCK DIAGRAM (c) System General Corp. Version 1.2.1(IAO33.0067.B2) -3- www.sg.com.tw * www.fairchildsemi.com September 28, 2007 Product Specification Low Cost Green-Mode PWM Controller for Flyback Converters SG6859 ABSOLUTE MAXIMUM RATINGS Symbol VVDD VFB VSENCE TJ RJA TSTG TL VESD-HBM VESD-MM Parameter DC Supply Voltage * Input Voltage to FB Pin Input Voltage to Sense Pin Operating Junction Temperature Thermal Resistance (Junction to Air) Storage Temperature Range Lead Temperature (Wave soldering or IR, 10 seconds) ESD Capability, HBM Model ESD Capability, Machine Model Value 30 -0.3 to 7 -0.3 to 7 150 SOT DIP 260 3.5 200 208.4 82.5 Unit V V V C C/W C/W C C kV V -55 to +150 * All voltage values, except differential voltages, are given with respect to GND pin. * Stresses beyond those listed under "absolute maximum ratings" may cause permanent damage to the device. RECOMMENDED OPERATING CONDITIONS Symbol VDD TA Parameter DC Supply Voltage Operating Ambient Temperature Value 22 -20 to +85 Unit V C * For proper operation. ELECTRICAL CHARACTERISTICS (VDD = 15V; TA = 25C) VDD Section Symbol VDD-OP VDD-ON VDD-OFF IDD-ST IDD-OP VDD-OVP tD-VDDOVP VDD-G OFF Parameter Continuously Operation Voltage Turn-On Threshold Voltage Turn-Off Threshold Voltage Startup Current Operating Supply Current VDD Over-voltage-protection level VDD Low-threshold Voltage to Exit Green-off Mode Test Condition Min. 15.5 10.5 Typ. 16.5 11.5 9 3 Max. 22 17.5 12.5 15 3.5 26 Unit V V V A mA V s V VDD=VDD-ON - 0.1V VDD=15V, GATE with 1nF to GND (Auto Restart) 24 25 125 VDD-OFF + 1 VDD Over-voltage-protection Debounce (Auto Restart) (c) System General Corp. Version 1.2.1(IAO33.0067.B2) -4- www.sg.com.tw * www.fairchildsemi.com September 28, 2007 Product Specification Low Cost Green-Mode PWM Controller for Flyback Converters SG6859 Feedback Input Section Symbol ZFB VFB-OPEN VFB-OL tD-OLP VFB-N VFB-G SG Parameter Input Impedance FB Output High Voltage FB Open-loop Trigger Level The delay time of FB pin Open Loop Protection Green-Mode Entry FB Voltage Green-Mode Ending FB Voltage Green-Mode Modulation Slope Test Condition Min. 5 4.3 2.6 Typ. 5 4.6 56 2.85 2.20 75 Max. Unit K V 4.9 3.1 100 V ms V V Hz/mV RI=95K 40 Current Sense Section Symbol ZSENSE tPD VSTHFL VSTHVA tLEB DCYSAW Parameter Input Impedance Delay to Output Flat Threshold Voltage for Current Limit Valley Threshold Voltage for Current Limit Leading-Edge Blanking Time Duty Cycle of SAW Limit Test Condition Min. 10 40 0.91 0.75 250 Typ. 55 0.96 0.80 300 40 Max. 100 1.01 0.85 350 Unit K ns V V ns % Oscillator Section Symbol FOSC THOP FOSC-G FDV FDT Parameter Normal PWM Frequency Hopping Period Green-Mode Frequency Frequency Variation versus VDD Deviation Frequency Variation versus Temp. Deviation Center Frequency Hopping Range Test Condition RI=95K RI=95K RI=95K VDD=13.5 to 22V TA=-20 to 85C Min. 65 Typ. 70 4.9 3.7 22 Max. 75 Unit KHz ms KHz 0 0.02 2 2 % % Output Section Symbol DCYMAX VGATE-L VGATE-H tr tf VGATE-CLAMP Parameter Maximum Duty Cycle Output Voltage Low Output Voltage High Rising Time Falling Time Output Clamp Voltage Test Condition VDD=15V, Io=20mA VDD=13.5V, Io=20mA VDD=15V, CL=1nF VDD=15V, CL=1nF VDD=22V Min. 70 8 Typ. 75 Max. 80 1.5 Unit % V V ns ns 150 55 16 17 18 V (c) System General Corp. Version 1.2.1(IAO33.0067.B2) -5- www.sg.com.tw * www.fairchildsemi.com September 28, 2007 Product Specification Low Cost Green-Mode PWM Controller for Flyback Converters SG6859 TYPICAL CHARACTERISTICS Turn-On Threshold Voltage (VDD-ON) vs Temperature 17.0 14 13 12 11 10 9 8 Turn-Off Threshold Voltage (VDD-OFF) vs Temperature 16.8 16.6 16.4 16.2 16.0 -40 -25 -10 5 20 35 50 65 80 95 110 125 VDD-OFF (V) VDD-ON (V) -40 -25 -10 5 20 35 50 65 80 95 110 125 Temperature () Temperature () Startup Current (IDD-ST) vs Temperature 1.4 1.2 1.0 0.8 0.6 0.4 0.2 -40 -25 -10 5 20 35 50 65 80 95 110 125 3.0 Operating Supply Current (IDD-OP) vs Temperature 2.8 IDD-OP (mA) IDD-ST (uA) 2.6 2.4 2.2 2.0 -40 -25 -10 5 20 35 50 65 80 95 110 125 Temperature () Temperature () Normal PWM Frequency (FOSC) vs Temperature 72.0 75.0 Maximum Duty Cycle (DCYMAX) vs Temperature 74.8 71.5 DCYMAX (%) FOSC (Khz) 74.6 71.0 74.4 70.5 74.2 70.0 -40 -25 -10 5 20 35 50 65 80 95 110 125 74.0 -40 -25 -10 5 20 35 50 65 80 95 110 125 Temperature () Temperature () (c) System General Corp. Version 1.2.1(IAO33.0067.B2) -6- www.sg.com.tw * www.fairchildsemi.com September 28, 2007 Product Specification Low Cost Green-Mode PWM Controller for Flyback Converters SG6859 Green-Mode Entry FB Voltage (VFB-N) vs Temperature 3.2 2.30 Green-Mode Ending FB Voltage (VFB-G) vs Temperature 3.0 2.28 VFB-N (V) 2.6 VFB-G (V) -40 -25 -10 5 20 35 50 65 80 95 110 125 2.8 2.26 2.24 2.4 2.22 2.2 2.20 -40 -25 -10 5 20 35 50 65 80 95 110 125 Temperature () Temperature () Leading-Edge Blanking Time (tLEB) vs Temperature 340 330 3.0 3.5 Op er atin g Su p p ly C u r rent v s VDD v o ltag e IDD-OP (mA) -40 -25 -10 5 20 35 50 65 80 95 110 125 320 tLEB (ns) 2.5 310 300 290 280 2.0 1.5 1.0 12 13 14 15 16 17 18 19 20 21 22 23 24 Temperature () VDD (V) (c) System General Corp. Version 1.2.1(IAO33.0067.B2) -7- www.sg.com.tw * www.fairchildsemi.com September 28, 2007 Product Specification Low Cost Green-Mode PWM Controller for Flyback Converters SG6859 OPERATION DESCRIPTION SG6859 devices integrate many useful designs into one controller for low-power switch-mode power supplies. The following descriptions highlight some of the features of the SG6859 series. Each time the power MOSFET is switched on, a turn-on spike will inevitably occur at the sense-resistor. To avoid premature termination of the switching pulse, a 320nsec leading edge blanking time is built in. Conventional RC filtering can therefore be omitted. During this blanking period, the current-limit comparator is disabled and it cannot switch off the gate driver. Start-up Current The start-up current is only 9uA. Low start-up current allows a start-up resistor with a high resistance and a low-wattage to supply the start-up power for the controller. A 1.5 M, 0.25W, start-up resistor and a 10uF/25V VDD hold-up capacitor would be sufficient for an AC-to-DC power adapter with a wide input range (100VAC to 240VAC). Constant Output Power Limit When the SENSE voltage across the sense resistor Rs reaches the threshold voltage (around 0.96V), the output GATE drive will be turned off following a short propagation delay tPD. This propagation delay will introduce an additional current proportional to tPD*Vin/Lp. The propagation delay is nearly constant regardless of the input line voltage VIN. Higher input line voltages will result in larger additional currents. At high input line voltages, the output power limit will be higher than at low input line voltages. To compensate for this output power limit variation across a wide AC input range, the threshold voltage is adjusted by adding a positive ramp. This ramp signal rises from 0.80V to 0.96V, and then flattens out at 0.96V. A smaller threshold voltage forces the output GATE drive to terminate earlier. This reduces the total PWM turn-on time and makes the output power equal to that of low line input. This proprietary internal compensation ensures a constant output power limit for a wide AC input voltage range (90VAC to 264VAC). Operating Current The operating current has been reduced to 3mA. The low operating current results in higher efficiency and reduces the VDD hold-up capacitance requirement. Green-Mode Operation The proprietary green-mode function provides off-time modulation to linearly decrease the switching frequency under light-load conditions. On-time is limited to provide stronger protection against brownouts and other abnormal conditions. The feedback current, which is sampled from the voltage feedback loop, is taken as the reference. Once the feedback current exceeds the threshold current, the switching frequency starts to decrease. This green-mode function dramatically reduces power consumption under light-load and zero-load conditions. Power supplies using the SG6859 can easily meet even the strictest regulations regarding standby power consumption. Under Voltage Lockout (UVLO) The turn-on and turn-off thresholds of the SG6859 are fixed internally at 16.5V/11.5V. During start-up, the hold-up capacitor must be charged to 16.5V through the start-up resistor, so that the SG6859 will be enabled. The hold-up capacitor will continue to supply VDD until power can be delivered from the auxiliary winding of the main transformer. VDD must not drop below 11.5V during this start-up process. This UVLO hysteresis window ensures that hold-up capacitor will be adequate to supply VDD during start-up. Oscillator Operation A resistor connected from the RI pin to ground will generate a constant current source for the SG6859. This current is used to charge an internal capacitor. The charge-time determines the internal clock speed and the switching frequency. Increasing the resistance will reduce the amplitude of the input current and reduce the switching frequency. A 95k resistor Ri results in a 50uA constant current Ii and a 70kHz switching frequency. The relationship between Ri and the switching frequency is: fPWM = 6650 R I (k ) (kHz ) Leading-Edge Blanking www.sg.com.tw * www.fairchildsemi.com September 28, 2007 (c) System General Corp. Version 1.2.1(IAO33.0067.B2) -8- Product Specification Low Cost Green-Mode PWM Controller for Flyback Converters SG6859 Gate Output The SG6859 BiCMOS output stage is a fast totem pole gate driver. Cross conduction has been avoided to minimize heat dissipation, increase efficiency, and enhance reliability. The output driver is clamped by an internal 17V Zener diode in order to protect power MOSFET transistors against undesired over-voltage gate signals. Built-in Slope Compensation The sensed voltage across the current sense resistor is used for current mode control and pulse-by-pulse current limiting. Built-in slope compensation will improve stability and prevent sub-harmonic oscillations due to peak-current mode control. The SG6859 has a synchronized, positively-sloped ramp built-in at each switching cycle. The slope of the ramp is: 0.36 x Duty Duty (max .) Noise Immunity Noise from the current sense or the control signal can cause significant pulse width jitter, particularly in continuous-conduction mode. While slope compensation helps alleviate these problems, further precautions should still be taken. Good placement and layout practices should be followed. Avoiding long PCB traces and component leads, locating compensation and filter components near the SG6859, and increasing the power MOS gate resistance is advised. (c) System General Corp. Version 1.2.1(IAO33.0067.B2) -9- www.sg.com.tw * www.fairchildsemi.com September 28, 2007 Product Specification Low Cost Green-Mode PWM Controller for Flyback Converters SG6859 REFERENCE CIRCUIT 1 L F1 BD1 C3 CX1 R1 2 4 C1 C2 R5 3 1 N R2 R4 10 9 D1 U1 1 2 3 C6 R9 C11 R6 GND GATE FB RI VDD SENSE 6 5 4 R15 2 8 5 Q1 3 7 3,4 2 GND 2 R10 C7 C8 D5 C9 1 T1 1,2 2 D4 L2 1 1 2 VO R3 1 L1 2 R7 1 R8 C4 1 D2 2 R11 R13 4 U2 R14 3 2 C10 3 U3 1 R12 2 CY1 BOM Reference BD1 CX1 CY1 C1 C2 C3 C4 C6 C7 C8 C9 C10 C11 D1 D2 D4 D5 F1 L1 (Optional) (Optional) (Optional) (Optional) Component BD 1A/500V XC 0.1uF YC 102P/400V (Y1) CC 103P/500V EC 10F/400V 105C CC 102P/500V EC 10/50V CC 472P 0805 CC 102P/100V 1206 EC 470/10V 105C EC 220/10V 105C CC 222P 0805 N.C. Diode FRI07 Diode FR102 Diode SB360 ZD 6.8V 0.5W R 1/0.5W 20mH 6*8mm Reference L2 Q1 R1,R2 R3,R4 R5 R6 R7 R8 R9 R10 R11 R12 R13 R14 R15 T1 U1 U2 U3 1 Component 10uH 6mm MOSFET 1A/600V R 750K 1206 R 47K 1206 R 47 1206 R 4.7 1206 R 100 0805 R 10 1206 R 100K 0805 (Optional) R 10 1206 R 100 1/8W R 33K 0805 R 33K 1/8W R 4.7K 0805 R 0 0805 EE-16 IC SG6859 PC817 TL431 (c) System General Corp. Version 1.2.1(IAO33.0067.B2) - 10 - www.sg.com.tw * www.fairchildsemi.com September 28, 2007 Product Specification Low Cost Green-Mode PWM Controller for Flyback Converters SG6859 PACKAGE INFORMATION 8 PINS - DIP (D) D 8 5 X E1 E eB 1 4 A1 A2 L b1 b e Dimensions Symbol A A1 A2 b b1 D E E1 e L eB 2.921 8.509 0 6.223 9.017 0.381 3.175 3.302 1.524 0.457 9.271 7.620 6.350 2.540 3.302 9.017 7 3.810 9.525 15 0.115 0.335 0 6.477 0.245 10.160 0.355 3.429 Millimeters Min. Typ. A Max. 5.334 Inches Min. 0.015 0.125 Typ. Max. 0.210 0.130 0.060 0.018 0.365 0.300 0.250 0.100 0.130 0.355 7 0.135 0.400 0.255 0.150 0.375 15 (c) System General Corp. Version 1.2.1(IAO33.0067.B2) - 11 - www.sg.com.tw * www.fairchildsemi.com September 28, 2007 Product Specification Low Cost Green-Mode PWM Controller for Flyback Converters SG6859 6 PINS - SOT (T) D b 6 4 Detail A E1 E 1 e1 e 3 c 1 R A2 A L A1 L1 1 Detail A Dimensions Symbol A A1 A2 b c D E E1 e e1 L L1 L2 R R1 1 0.10 0.10 0 5 4 10 0.25 8 15 0.30 0.90 0.30 0.08 2.90 2.80 1.60 0.95 1.90 0.45 0.60 0.25 0.004 0.004 0 5 4 10 0.010 8 15 0.60 0.020 1.15 Millimeters Min. Typ. Max. 1.45 0.15 1.30 0.50 0.22 Inches Min. 0.036 0.011 0.003 0.045 0.114 0.110 0.063 0.037 0.075 0.018 0.024 0.010 0.024 (c) System General Corp. Version 1.2.1(IAO33.0067.B2) - 12 - www.sg.com.tw * www.fairchildsemi.com September 28, 2007 L2 1 R Typ. Max. 0.057 0.006 0.051 0.020 0.009 Product Specification Low Cost Green-Mode PWM Controller for Flyback Converters SG6859 (c) System General Corp. Version 1.2.1(IAO33.0067.B2) - 13 - www.sg.com.tw * www.fairchildsemi.com September 28, 2007 |
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