1、September 2012FAN6862WHighly Integrated Green-ModeControllerFeaturesDescriptionA highly integrated provides several features to§§§§Low Standby Power: Under 0.1 W Low Startup Current: 8 µALow Operating Current in Green Mode: 600 µAPeak-Current Mode Operation with Cycle-b

2、y-Cycle Current LimitingFrequency Continuously Decreasing with Burst Mode at Light Loadscontroller, FAN6862W enhance the performanceof flyback converters. To minimize standby powerconsumption, a proprietary Green Mode provides off- time modulation to continuously decrease the switching frequency und

3、er light-load conditions. Under zero-load conditions, the power supply enters Burst Mode, which§completely shuts offoutput. Output restarts justbefore the supply voltage drops below the UVLO lowerlimit. Green Mode enables powers to meet§§§§VDD Over-Voltage(OVP)international

4、power conservation requirements.Constant Output Power Limit (Full AC Input Range)Internal Latch Circuit (FAN6862WL) for OVP, OTPThe FAN6862W is designed for SMPS and integrates afrequency-hopfunction that helps to reduce EMIemission of a power supply with minimum line filters. To compensate the powe

5、r limit variation over universal input range, a bias current limit (VLIMIT) adaptively keeps the power limit subst ally constant. The gate output is clamped at 13.5 V to protect the external MOSFET from over-voltage damage.Fixed HopFrequency (65 KHz) with Frequency§§§§§§

6、;§Feedback Open-Loop: 60 ms DelayGATE Outputum Voltage Clamp: 13.5VSoft-Start Time: 5 msSoft Driving for EMI Improvement Full Range Frequency HopInternal OTP Sensor with HysteresisGate Driving Capability: 400 mAOtherfunctions includeVDDOver-Voltage(OVP), and Over-Temperature(OTP). For OTP, an e

7、xternal NTC thermistor can beapplied to sense the ambient temperature. WhenVDDOVP or OTP i off the controller.Table 1.ivated, an internal latch circuit latches types are shown in Table 1.TypeApplicationsGeneral-purpose switched-mode power flyback power converters, including:s and§§§Po

8、wer Adapters Open-Frame SMPSSMPS with Surge-Current Output, such as for Printers, Scanners, Motor DriversOrdering Information© 2012 Fairchild Semiconductor Corporation FAN6862W Rev. 1.0.0FAN6862W Highly Integrated GCorenetrno-MlleordePart NumberOperating Temperature RangePackagePacking MethodFA

9、N6862WTY-40 to +105°C6-Lead, SOT23, JEDEC MO-178 Variation AB, 1.6 mm WideTape & ReelFAN6862WLTYFAN6862WRTYPart NumberOVPOLPOTP / OTP2FAN6862WLatchA/RLatchFAN6862WLLatchLatchLatchFAN6862WRA/RA/RA/RTypical ApplicationFigure 1.Typical ApplicationBlock DiagramFigure 2. Block Diagram© 2012

10、 Fairchild Semiconductor Corporation FAN6862W Rev. 1.0.02FAN6862W Highly Integrated GCorenetrno-MlleordeMarking InformationFigure 3. Top MarkPin ConfigurationFigure 4.Pin ConfigurationPin Definitions© 2012 Fairchild Semiconductor Corporation FAN6862W Rev. 1.0.03FAN6862W Highly Integrated GCoren

11、etrno-MlleordePin #NameFunctionDescription1GNDGroundGround2FBFeedbackThe FB pin provides the output voltage regulation signal. It provides feedback to the internalcomparator, so thecomparator can control the duty cycle. This pin also provides over-current. IF VFB is higher than the trigger level and

12、 persists at that level, the controller stops and restarts.3RTTemperature DetectionAn external NTC thermistor is connected from this pin to the GND pin. The impedance of the NTC decreases at high temperatures. If the voltage of the RT pin drops below the threshold,output is disabled.4SENSECurrenseTh

13、is pin senses the voltage across a resistor. When the voltage reaches the internal threshold,output is disabled and thiivates over-current. This pin also provides current amplitude information for Current Mode control.5VDDPower SupplyPower supply6GATEDriver OutputThe totem-pole output driver for dri

14、ving the power MOSFETAxx:ABY: FAN6862WTYABZ: FAN6862WRTY ACA: FAN6862WLTYTT:Wafer Lot Code: Year Code_ _ _:Week CodeAbsoluteum RatingsStresses exceeding the absoluteum ratings may damage the device. The device may not function or beoperable above the recommended operating conditions and stressing th

15、e parts to these levels is not recommended.In addition, extended exposure to stresses above the recommended operating conditions may affect device reliability.The absolute respect to GND pin.um ratings are stress ratings only. All voltage values, except differential voltages, are given withRecommend

16、ed Operating ConditionsThe 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 notrecommend exceeding them or designing to Absoluteum Ra

17、tings.© 2012 Fairchild Semiconductor Corporation FAN6862W Rev. 1.0.04FAN6862W Highly Integrated GCorenetrno-MlleordeSymbolParameterMin.Max.UnitTAOperating Ambient Temperature-40+105°CSymbolParameterMin.Max.UnitVDDSupply Voltage30VVLInput Voltage to FB, SENSE, and RT Pins-0.37.0VJAThermal(J

18、unction-to-Ambient)244°C/WTJOperating Junction Temperature-40+125°CTSTGStorage Temperature Range-55+150°CTLLead Temperature, Wave Soldering, 10 Seconds+260°CESDHuman Body M, JESD22-A1145.5kVCharge Device M, JESD22-C1012.0Electrical CharacteristicsVDD = 15 V and TA = 25°C, un

19、less otherwise noted.Continued on the following page© 2012 Fairchild Semiconductor Corporation FAN6862W Rev. 1.0.05FAN6862W Highly Integrated GCorenetrno-MlleordeSymbolParameterConditionMin.Typ.Max.UnitVDD SectionVDD-OPContinuously Operating Voltage20VVDD-ONTurn-On Threshold Voltage151617VVDD-O

20、FFTurn-Off Voltage6.57.07.5VVDD-LHThreshold Voltage for Latch-Off ReleaseFAN6862W, FAN6862WL Only4VIDD-STStartup CurrentVDD-ON 0.16 V815µAIDD-OP1Operating Supply Current inOperationVDD = 20 V,VFB = 3 V Gate Open2mAIDD-OP2Operating Supply Current when VFB < VFB-ZDCVDD = 15 V, VFB < VFB-ZDC

21、600µAVDD-OVPVDD Over-VoltageFAN6862WL-Latch, FAN6862WR-AutoRestart21.022.223.5VtD-VDDOVPVDD OVP Debounce Time50µsIDD-LHLatch-Off Holding CurrentVDD = 5 V; FAN6862W, FAN6862WL Only7080µAFeedback Input SectionAVInput-Voltage to Currense Attenuation1/4.01/3.51/3.0V/VZFBInput Impedance17k

22、VFB-OPENFB Pin Open Voltage5.25.45.6VVFB-OLPThreshold Voltage for Open-Loop4.34.64.9VtD-OLPOpen-LoopDelayVFB > VFB-OLP, tON > 2.5 µs,TA = -40 to +105°C546066mstD-SCPSecondary Short-CircuitDelayFB > VFB-OLP, tON < 2.5 µs,TA = -40 to +105°C678mstON-SCPShort-CircuitOn-Ti

23、me DetectionVFB>VFB-OLP,TA = -40 to +105°C2.5µsCurrense SectiontPDDelay to Output100250nstLEBLeading-Edge Blanking Time200250nsVLIMIT-HHigh Threshold Voltage for Current LimitDuty>55%0.570.600.63VVLIMIT-LLow Threshold Voltage for Current LimitDuty = 0%0.360.390.42VtSOFT-STARTPeriod D

24、uring Startup TimeStartup Time4.755.0010.00msElectrical Characteristics (Continued)VDD = 15 V and TA = 25°C, unless otherwise noted.Continued on following pageFrequencyfOSCfOSC-GVFB-ZDC VFB-ZDCR VFB-GVFB-NVFBFigure 5.Frequency© 2012 Fairchild Semiconductor Corporation FAN6862W Rev. 1.0.06F

25、AN6862W Highly Integrated GCorenetrno-MlleordeSymbolParameterConditionMin.Typ.Max.UnitOscillator SectionfOSCNormalFrequencyCenter FrequencyVFB > VFB-N606568kHzHopRangeVFB ³ VFB-N±4.0VFB = VFB-G(1)±2.9thop-1HopPeriod 1(1)VFB ³ VFB-N4.4msthop-3HopPeriod 3(1)VFB = VFB-G11.5msfOSC

26、-GGreen Mode Minimum Frequency182226kHzVFB-NFB Threshold Voltage for Frequency Reduction2.352.502.65VVFB-GFB Voltage at fOSC-G2.052.202.30VVFB-ZDCFB Threshold Voltage for Zero-Duty1.6VVFB-ZDCR - VFB-ZDCZDC Hysteresis0.15VfDVFrequency Variation vs. VDD DeviationVDD = 7.5 V to 21 V0.52.0%fDTFrequency

27、Variation vs. Temperature Deviation(1)TA = -40 to +105°C2%Electrical Characteristics (Continued)VDD = 15 V and TA = 25°C, unless otherwise noted.Notes:1. Guarantee by design.2. When activated, the output is disabled and the latch is turned off.3. The threshold temperature for enabling the

28、output again and resetting the latch after OTP has been activated.© 2012 Fairchild Semiconductor Corporation FAN6862W Rev. 1.0.07FAN6862W Highly Integrated GCorenetrno-MlleordeSymbolParameterConditionMin.Typ.Max.UnitOutput SectionDCYMAXum Duty Cycle607075%VOLOutput Voltage LOWVDD = 15 V, IO = 5

29、0 mA1.5VVOHOutput Voltage HIGHVDD = 8 V, IO = 50 mA6VtRRising Time (with Soft Driving)GATE = 1 nF150nstFFalling TimeGATE = 1 nF35nsVCLAMPGate Output ClamVoltageVDD = 20 V12.013.515.0VIO-SOURCEGate Source Driving Capability(1)VDD = 15 V400mAIO-SINKGate Sink Driving Capability(1)VDD = 15 V400mAOver-Te

30、mperature(OTP) SectionRRTum Externalof RT Pin to Trigger91011kVOTPThreshold Voltage for Over-TemperatureFAN6862W, FAN6862WL-Latch, FAN6862WR-AutoRestart, at 25°C0.941.001.06VIRTOutput Current of RT Pin92100108AtDOTPOver-Temperature Debounce TimeVFB=VFB-N141719msVOTP2Second Threshold Voltage for

31、 Over- TemperatureFAN6862W, FAN6862WL-Latch, FAN6862WR-AutoRestart, at 25°C0.650.700.75VtDOTP2Second Over-Temperature Debounce Time80135200µsTOTPJunction Temperature(1,2)+135°CTRestartRestart Junction Temperature (1,3)TOTP- 25°CTypical Performance CharacteristicsFigure 6. Turn-On

32、 Threshold Voltage (VDD-ON) vs. TemperatureFigure 7.Turn-Off Threshold Voltage (VDD-OFF) vs. TemperatureFigure 8. Operating Current (IDD-OP2) vs. TemperatureFigure 9.VDD Over-Voltagevs. Temperature(VDD-OVP)Figure 10. Center Frequency (fOSC) vs. TemperatureFigure 11. FB Threshold Voltage for Frequenc

33、y Reduction (VFB-N) vs. Temperature© 2012 Fairchild Semiconductor Corporation FAN6862W Rev. 1.0.08FAN6862W Highly Integrated GCorenetrno-MlleordeTypical Performance Characteristics (Continued)Figure 12. FB Voltage at fOSC-G (VFB-G) vs. TemperatureFigure 13.Threshold Voltage for Open-Loop (VFB-O

34、LP) vs. TemperatureFigure 14. Open-Loopvs. TemperatureDelay (tD-OLP)Figure 15. Flat Threshold Voltage for Current Limit (VLIMIT-H) vs. TemperatureFigure 16. Valley Threshold Voltage for Current Limit (VLIMIT-L) vs. TemperatureFigure 17. GATE Output ClamVoltage (VCLAMP) vs. Temperature© 2012 Fai

35、rchild Semiconductor Corporation FAN6862W Rev. 1.0.09FAN6862W Highly Integrated GCorenetrno-MlleordeTypical Performance Characteristics (Continued)Figure 18.um Duty Cycle (DCYMAX) vs. TemperatureFigure 19. Leading-Edge Blanking Time (tLEB)Temperaturevs.Figure 20. Rising Time (tR) vs. TemperatureFigu

36、re 21. Falling Time (tF) vs. TemperatureFigure 22. Output Current of RT Pin (IRT) vs.TemperatureFigure 23.um External Triggerof RT Pin to(RRT)vs. Temperature© 2012 Fairchild Semiconductor Corporation FAN6862W Rev. 1.0.010FAN6862W Highly Integrated GCorenetrno-MlleordeOperation DescriptionStartu

37、p OperationFigure 24 shows a typical startup circuit and transformer auxiliary winding for a typical application. Before switching operation begins, FAN6862W consumes onlystartup current (typically 8 µA) and the currentdthrough the startup resistor charges thecapacitorVDD(CDD). When VDD reaches

38、 turn-on voltage of 16 V (VDD- ON), switching begins and the current consumedincreases to 2 mA. Power is thend from thetransformer auxiliary winding. The large hysteresis ofVDD (7 V) provides mooldup time, which allows usinga small capacitor for VDD. The startup resistor is typicallyconnected to AC

39、line for a fast reset of latch.Figure 25.FrequencyFigure 24. Startup CircuitGreen-Mode OperationThe FAN6862W uses feedback voltage (VFB) as an indicator of the output load and modulates the frequency, as shown in Figure 25, such that the switching frequency decreases as load decreases. In heavy-load

40、 conditions, the switching frequency isFigure 26. Burst-Mode OperationFrequency HopEMI reduction is accomplished by frequency hop,which sps the energy over a wider frequency rangethan the bandwidth measured by the EMI test65 kHz. Oncedecreases belowVFBVFB-N(2.5 V), theequipment.Aninternalfrequency-h

41、opcircuitfrequency starts to linearly decrease from 65 kHzchanges the switching frequency between 61.0 kHz and69.0 kHz with a period of 4.4 ms, as shown in Figure 27.to 22.5 kHz to reduce the switching losses. AsVFBdecreases below VFB-G (2.2 V), the switching frequency is fixed at 22.5 kHz and FAN68

42、62W enters “deep” Green Mode, where the operating current decreases toThis covers the whole frequency range and shrinks the period with operation frequency proportionally.600 µA (um), further reducing the standby powerconsumption. Asdecreases belowVFBVFB-ZDC(1.6V),FAN6862W enters Burst-Mode ope

43、ration. WhenVFBdrops belowVFB-ZDC,switching stops and the outputvoltage starts to drop, which causes the feedbackvoltage to rise. Once VFB rises above VFB-ZDC, switching resumes. Burst Mode alternately enables and disables switching, thereby reducing switching loss in Standby Mode, as shown in Figur

44、e 26.Figure 27. Frequency Hop© 2012 Fairchild Semiconductor Corporation FAN6862W Rev. 1.0.011FAN6862W Highly Integrated GCorenetrno-MlleordesSelf-protective functions includeOpen-Loop / Overload(OLP)VDDOver-VoltageWhen the upper branch of the voltage divider for the shunt regulator (KA431 shown

45、 in Figure 29) is broken, no current flows through the photo-coupler transistor, which pulls up the feedback voltage to 5.4 V.When feedback voltage is above 4.6 V for longer than(OVP), Open-Loop / Overload(OLP), Over-Current(OCP), Short-Circuit(SCP) and Over-Temperature(OTP). OLP, OCP and SCP are Au

46、to-Restart Modes; OVP and OTP are Latch-ModeAuto-Restart Modes.60 ms, OLP is triggered. Thisis also triggeredwhen the SMPS output drops below the nominal value for longer than 60 ms due to the overload condition.If the secondary output-short situation occurs when theOnce a fault condition is detecte

47、d, switching isterminated and the MOSFET remains off. This causesVDDto fall because no more power is delivered fromauxiliary winding. Whenfalls to VDD-OFF (7 V), the is reset and the operating current reduces toVDDfeedback voltage is above 4.6 V, for shorter debounce time.time is 7 msstartup current

48、, which causesto rise. FAN6862WVDDresumes normal operation whenVDDreachesVDD-ON(16 V). In this manner, the auto-restart can alternately enable and disable the switching of the MOSFET until the fault condition is eliminated (see Figure 28).Figure 29. OLP OperationVDD Over-VoltageVDD over-voltageby ov

49、er voltage on the(OVP)prevents IC damage causedVDDpin. The OVP is triggeredwhenreaches 22.2 V. A debounce time (typicallyVDDFigure 28. Auto Restart OperationLatch-Mode50 µs) prevents false triggering by switching noise.Over-Temperature(OTP)Once thisis triggered, switching is terminatedThe OTP c

50、ircuit is composed of current source and voltage comparators. Typically, an NTC thermistor is connected between the RT and GND pins. If the voltageand the MOSFET remains off. The latch is reset onlywhenis discharged below 4 V by unplugging the AC power line.VDDof this pin drops below a threshold of 1.0 V,outputis disabled after tDOTP debounce time. If this pin voltage drops below 0.7 V, it triggers the latch-off immediately after tDOTP2 debounce time.Over-CurrentFAN6862W over-current(OCP)is a pulse-by-pulse that turns off thebias current limit threshold(VLIMIT)MOSFET once the sensing