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www.fairchildsemi.com
FEB157-001 User’s Guide
Offline High Brightness
LED Driver Evaluation Board
Featured Fairchild Product: FAN7554
© 2007 Fairchild Semiconductor Page 1 of 17 Rev 1.1 April 2007
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www.fairchildsemi.com Contents 1. Introduction ............................................................................................................................................3 1.1 Product Description..........................................................................................................................3 1.2 Circuit Description ...........................................................................................................................3 2. Electrical R
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www.fairchildsemi.com 1. Introduction 1.1 Product Description A high brightness LED evaluation board has been developed using the Fairchild Semiconductor FAN7554D PWM controller. The board has the capability of driving one, two or three Lumiled, or similar LEDs. The output current is user selectable at 350mA, 700mA, or 1A. The current is selectable by inserting or removing jumpers JP1 and JP2 on the evaluation board. The board is designed to operate over the universal AC line range of 90Vac
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www.fairchildsemi.com Since the output current is being controlled instead of the output voltage, the output voltage will actually vary with the number of LEDs on the output. The same applies to the auxiliary winding that provides the bias supply to the FAN7554D. Consequently, the transformer had to be designed to provide enough bias when powering one LED. Then when powering three LEDs, the bias voltage is significantly higher. In order to maintain reliable operation, a regulator circuit cons
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www.fairchildsemi.com Table 1: Jumper JP1/JP2 Status and LED Current LED Current JP1 Status JP2 Status 350mA Out Out 700mA In Out 1A In In Refer to the schematic in Figure 3. As the LED current returns back to the power supply, it develops a voltage across the sense resistor(s). Once this voltage reaches the base-emitter junction voltage of the NPN Q2, typically about 650mV, the transistor will conduct collector current. This current also flows through the photodiode inside the optocoupler, I
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www.fairchildsemi.com 2. Electrical Requirements 2.1 Input Requirements Voltage range: 90Vrms to 270Vrms Frequency: 47Hz to 63Hz 2.2 Output Requirements The FEB157 board will power one, two, or three high brightness LEDs (Lumiled or similar) at user selectable load currents of 350mA, 700mA, or 1A. © 2007 Fairchild Semiconductor Page 6 of 17 Rev 1.1 April 2007
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www.fairchildsemi.com 3. Designed Solution 3.1 Schematic LF1 2 R2 T1 22kΩ C2 C3 EFD20 Core/Bobbin 1 2010 47µF 1000pF R1 450V 1kV 5.6Ω 3 BD1 R3 1W DF10S 22kΩ 2010 C1 Lm = 610µH 2 0.1µF D1 RS1M R4 3 F1 C14 10Ω 1A, 250V R19 Prov. for 0805 1206 TP1 1 Prov. for 2010 R5 R6 L1 150kΩ 150kΩ 2 2.2µH TP4 D4 2010 2010 Q1 C15 SS39 R7 8 FQD2N80 100pF 22Ω 5 0805 C11 C12 6 1000µF 47µF R21 R14 R8 16V 50V J2 47Ω 1.8Ω, 2010 JP1 10kΩ 2010 0603 D2 R15 Prov. for MMBD4148 ZD2 2Ω, 2010 JP2 Prov. for SOD-123 TP3 Q3 MMB
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www.fairchildsemi.com 3.2 Transformer Required Components Schematic Winding Stackup 1 Core = EFD20 Vcc 25 T 1/2 Pri - 36 T Bobbin = 10 pin; SMD; Horizontal 2 1/2 Primary - 36 T 8 1/2 Pri - 36 T Secondary - 10T Output - 10 T 3 4 1/2 Primary - 36 T 6 Vcc - 25 T 5 Electrical Specifications Pin Spec. Remarks Inductance 1 - 3 537.0 - 656.0 uH 100 kHz, 0.10 Vrms All other windings shorted Leakage 1 - 3 3.3 Bill of Materials Sch Ref Vendor Part Number Description BD1 Fairchild DF10S 1.5A, 1000 V Bridg
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www.fairchildsemi.com 3.3 Bill of Materials (Continued) Sch Ref Vendor Part Number Description Conn1 Phoenix Contact 1729018 2 position terminal block Conn2 Tyco 535676-5 6 position connector D1 Fairchild RS1M 1A, 1000V, SMA D2 Fairchild Prov. for MMBD4148 D3 Fairchild BAS21 0.2A, 250V, SOT-23 D4 Fairchild SS39 3A, 90V, SMC F1 Littlefuse 3721100 1A, 250V, Slo-Blo IC1 Fairchild FAN7554D PWM Controller, SO-8 IC2 Fairchild FOD817A Optocoupler JP1 Sullins PRPN021PAEN-RC 2 pin header (2mm) JP2 Sullin
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www.fairchildsemi.com 3.3 Bill of Materials (Continued) Sch Ref Vendor Part Number Description R17 NIC Components or Equivalent NRC06J511TR 510Ω , 1/10 W, 0603 R18 NIC Components or Equivalent NRC06J101TR 100Ω , 1/10 W, 0603 R19 Prov. for 2010 R20 NIC Components or Equivalent NRC50J102TR 1kΩ , 3/4 W, 2010 R21 NIC Components or Equivalent NRC50J470TR 47Ω , 3/4 W, 2010 RTH1 NIC Components or Equivalent NCT08AJ104334TR 10kΩ , NTC Thermistor, Beta = 3340 T1 Cooper CTX0117893 EFD20 Core/Bobbin Transf
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www.fairchildsemi.com Figure 5: Silkscreen/Component Placement of Top Side Layer Figure 6: Silkscreen/Component Placement of Bottom Side Layer © 2007 Fairchild Semiconductor Page 11 of 17 Rev 1.1 April 2007
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www.fairchildsemi.com 4. Test Results 4.1 Regulation 4.1.1 Line Regulation This graph illustrates the regulation of the output current over line voltage for the three possible settings, 350mA, 700mA, and 1A. 1200 1000 800 1 LED 2 LEDs 600 3 LEDs 400 200 0 90 120 270 Input Voltage (Vac) Figure 7: LED Current vs. Line Voltage © 2007 Fairchild Semiconductor Page 12 of 17 Rev 1.1 April 2007 LED Current (mA)
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www.fairchildsemi.com 4.2 Efficiency The efficiency data shown is for the converter with a load of one, two and three LEDs driven at 1A. 90 80 70 60 1 LED @ 1 A 50 2 LEDs @ 1 A 40 3 LEDs @ 1 A 30 20 10 0 90 120 270 Input Voltage (V) Figure 8: Converter Efficiency Data Plotted Against Increasing Line Input for LED Current of 1A. © 2007 Fairchild Semiconductor Page 13 of 17 Rev 1.1 April 2007 Efficiency (%)
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www.fairchildsemi.com 4.3 Steady State Operation Figure 9: Steady State Waveforms at 90Vac with Three LEDs at 1A Figure 10: Steady State Waveforms at 270Vac with One LED at 350mA © 2007 Fairchild Semiconductor Page 14 of 17 Rev 1.1 April 2007
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www.fairchildsemi.com 4.4 Start up The startup profile is captured at 90Vac and 270Vac with a load of three LEDs operating at a current of 1A. Figure 11: Startup Profile at 90 Vac with Three LEDs at 1A Figure 12: Startup Profile at 270Vac with Three LEDs at 1A © 2007 Fairchild Semiconductor Page 15 of 17 Rev 1.1 April 2007
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www.fairchildsemi.com Warning and Disclaimer: This Evaluation Board may employ high voltages so appropriate safety precautions should be used when operating this board. Replace components on the Evaluation Board only with those parts shown on the parts list in the User's Guide. Contact an authorized Fairchild representative with any questions. The Evaluation Board is for demonstration purposes only and neither the Board nor this User's Guide constitute a sales contract or create any kind of
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www.fairchildsemi.com © 2007 Fairchild Semiconductor Page 17 of 17 Rev 1.1 April 2007
