National Semiconductor Application Note 2061 Clinton Jensen August 11, 2010 Introduction istics including EMI/EMC data. The above restrictions for the input voltage are valid only for the demonstration board as shipped with the schematic below. Please refer to the LM3445 data sheet for detailed information regarding the LM3445 device. The board is currently set up to drive five to thirteen series connected LEDs, but the evaluation board may be modified to accept more series LEDs. Refer to the tables in this document for modifying the board to accept more LEDs and/or adjust for different current levels. The evaluation board included in this shipment converts 85VAC to 135VAC input and drives five to thirteen series connected LED’s at the currents listed in the Evaluation Board Operating Conditions section. This is a two-layer board using the bottom and top layer for component placement. The board is surrounded by a larger area allowing for extra test points and connectors for ease of evaluation. The actual board size is contained inside the larger outer area and can be cut out for the smallest size possible. The evaluation board can be modified to adjust the LED forward current and the number of series connected LEDs. The topology used for this evaluation board eliminates the need for passive power factor correction and results in high efficiency and power factor with minimal component count which results in a size that can fit in a standard A19 Edison socket. This board will also operate correctly and dim smoothly using most standard triac dimmers. Output current is regulated within ±15% of nominal from circuit to circuit and over line voltage variation. Refer to the LM3445 datasheet for details on the LM3445 IC. A bill of materials below describes the parts used on this demonstration board. A schematic and layout have also been included below along with measured performance character- Evalution Board Operating Conditions VIN = 85VAC to 135VAC 5 to 13 series connected LEDs as configured with the currents listed below Can drive up to 18 series LEDs (see table) ILED = 340 mA (5 LEDs) ILED = 300 mA (7 LEDs) ILED = 260 mA (9 LEDs) ILED = 230 mA (11 LEDs) ILED = 205 mA (13 LEDs) LM3445 A19 Edison Retrofit Evaluation Board LM3445 A19 Edison Retrofit Evaluation Board Simplified LM3445 Schematic 30124601 Warning: This LM3445 evaluation PCB is a non-isolated design. The ground connection on the evaluation board is NOT referenced to earth ground. If an oscilloscope ground lead is connected to the evaluation board ground test point for analysis, and AC power is applied, the fuse (F1) will fail open. The oscilloscope should be powered via an isolation transformer before an oscilloscope ground lead is connected to the evaluation board. © 2010 National Semiconductor Corporation 301246 www.national.com AN-2061 Warning: The LM3445 evaluation boards have no isolation or any type of protection from shock. Caution must be taken when handling evaluation board. Avoid touching evaluation board, and removing any cables while evaluation board is operating. Isolating the evaluation board rather than the oscilloscope is highly recommended. AN-2061 Pin-Out 30124603 10-Pin MSOP Pin Description 10 Pin MSOP Pin # Name Description 1 ASNS PWM output of the triac dim decoder circuit. Outputs a 0 to 4V PWM signal with a duty cycle proportional to the triac dimmer on-time. 2 FLTR1 First filter input. The 120Hz PWM signal from ASNS is filtered to a DC signal and compared to a 1 to 3V, 5.85 kHz ramp to generate a higher frequency PWM signal with a duty cycle proportional to the triac dimmer firing angle. Pull above 4.9V (typical) to tri-state DIM. 3 DIM Input/output dual function dim pin. This pin can be driven with an external PWM signal to dim the LEDs. It may also be used as an output signal and connected to the DIM pin of other LM3445 or LED drivers to dim multiple LED circuits simultaneously. 4 COFF OFF time setting pin. A user set current and capacitor connected from the output to this pin sets the constant OFF time of the switching controller. 5 FLTR2 Second filter input. A capacitor tied to this pin filters the PWM dimming signal to supply a DC voltage to control the LED current. Could also be used as an analog dimming input. 6 GND Circuit ground connection. 7 ISNS LED current sense pin. Connect a resistor from main switching MOSFET source, ISNS to GND to set the maximum LED current. 8 GATE Power MOSFET driver pin. This output provides the gate drive for the power switching MOSFET of the buck controller. 9 VCC 10 BLDR www.national.com Input voltage pin. This pin provides the power for the internal control circuitry and gate driver. Bleeder pin. Provides the input signal to the angle detect circuitry as well as a current path through a switched 230Ω resistor to ensure proper firing of the triac dimmer. 2 AN-2061 30124607 LM3445 Evaluation Board Schematic 3 www.national.com AN-2061 Bill of Materials LM3445 Evaluation Board REF DES Description MFG U1 IC DRIVER LED W/TRIAC DIM 10MSOP National Semiconductor MFG Part Number LM3445MM C1, C10 Ceramic, 47000pF, 500V, X7R, 1210 Johanson Dielectrics 501S41W473KV4E C2 CAP FILM MKP .0047µF 310VAC X2 Vishay/BC Components BFC233820472 C3 CAP 470µF 50V ELECT PW RADIAL Nichicon UPW1H471MHD TDK Corporation C4532X7R2E334K C4/RBLDR (Note 1) DNP C5 Ceramic, .33µF, 250V, X7R, 1812 C6 CAP .10µF 305VAC EMI SUPPRESSION EPCOS B32921C3104M C8 Ceramic, 47µF, X5R, 16V, 1210 MuRata GRM32ER61C476ME15L C9 Ceramic, .1µF, 250V, X7R, 1210 Taiyo Yuden QMK325B7104KN-T C12 Ceramic, 470pF, 50V, X7R, 0603 MuRata GRM188R71H471KA01D C13, C15 Ceramic, 0.1µF, 16V, X7R, 0603 MuRata GRM188R71C104KA01D C14 Ceramic, 0.47µF, 16V, X7R, 0603 MuRata GRM188R71C474KA88D D1 DIODE SCHOTTKY 1A 200V PWRDI 123 Diodes Inc. DFLS1200-7 D2 Bridge Rectifier, Vr = 400V, Io = 0.8A, Vf = 1V Diodes Inc. HD04-T D4 DIODE FAST 1A 300V SMA Fairchild Semi conductor ES1F D7 DIODE ZENER 15V 500MW SOD-123 Fairchild Semi conductor MMSZ5245B D8 DIODE SCHOTTKY 1A 200V PWRDI 123 Diodes Inc. DFLS1200-7 F1 FUSE 1A 125V FAST Cooper/Bussman 6125FA1A J5, J10 CONN HEADER .312 VERT 2POS TIN Tyco Electronics 1-1318301-2 L1, L2 INDUCTOR 3900µH .12A RADIAL J.W. Miller/Bourns RL875S-392K-RC L3 820µH, Shielded Drum Core Coilcraft Inc. MSS1038-824KL M1 JUMPER WIRE 0.3" J6 TO J1 3M 923345-03-C M2 JUMPER WIRE 0.3" J7 to J4 3M 923345-03-C M3 JUMPER WIRE 0.3" J2 TO J8 3M 923345-03-C M4 JUMPER WIRE 0.3" J3 TO J9 3M 923345-03-C Q1 MOSFET N-CH 240V 260MA SOT-89 Infineon Technologies BSS87 L6327 Q2 MOSFET N-CH 250V 4.4A DPAK Fairchild Semi conductor FDD6N25TM R1, R3 RES 200kΩ, 0.25W, 1%, 1206 Vishay-Dale CRCW1206200kFKEA R2, R7 RES 274kΩ, 0.25W, 1%, 1206 Vishay-Dale CRCW1206274kFKEA R4 RES 430Ω, 1/2W, 5%, 2010 Vishay-Dale CRCW2010430RJNEF R5 RES 430Ω, 1/3W, 5%, 1210 Vishay-Dale CRCW1210430RJNEA R6, R24 RES 30.1kΩ, 0.25W, 1%, 1206 Vishay-Dale CRCW120630k1FKEA R8 RES 49.9kΩ, 0.1W, 1%, 0603 Vishay-Dale CRCW060349K9FKEA R9 RES 48.7kΩ, 0.1W, 1%, 0603 Vishay-Dale CRCW060348K7FKEA R10 DNP R12 RES 4.7Ω, 0.1W, 5%, 0603 Vishay-Dale CRCW06034R70JNEA R14 RES 1.54Ω, 1/4W, 1%, 1206 Vishay-Dale CRCW12061R54FNEA R15 RES 3.16kΩ, 0.1w, 1%, 0603 Vishay-Dale CRCW06033K16FKEA R16 RES 255kΩ, 0.1W, 1%, 0603 Vishay-Dale CRCW0603255KFKEA R22 RES 40.2Ω, 0.125W, 1%, 0805 Vishay-Dale CRCW080540R2FKEA RT1 CURRENT LIMITOR INRUSH 60Ω 20% Cantherm MF72-060D5 TP1, TP2, TP3, TP4 Terminal, Turret, TH, Double Keystone Electronics 1502-2 Note 1: C4/RBLDR is a dual purpose pad which is unpopulated by default. A ceramic capacitor (C4) may be used here if extra high frequency bypassing is desired across the LED load. Alternatively a bleeder resistor (RBLDR) in the range of 10kΩ to 100kΩ may be placed here to quickly discharge C3 and prevent prolonged LED glow due to the energy stored in C3. www.national.com 4 # of LEDs Output Current (mA) Original Circuit Output Current (mA) Modification A (Note 2) Output Current (mA) Modification B (Note 3) Output Current (mA) Modification C (Note 4) 2 520 3 500 4 475 5 340 248 265 455 6 315 235 250 432 7 300 222 237 412 8 275 210 224 9 260 200 212 10 245 190 200 11 230 180 190 12 215 170 180 13 205 164 170 14 (Note 5) 196 156 162 15 (Note 5) 190 150 155 16 (Note 5) 183 142 148 17 (Note 5) 175 135 142 18 (Note 5) 170 130 137 Note 2: Modification A: R14 = 2.37Ω, R16 = 150kΩ, C3 = 330µF, 63V. Note 3: Modification B: R14 = 2.2Ω, R16 = 165kΩ. Note 4: Modification C: R14 = 1.2Ω, R16 = 137kΩ, L3 = 470µH, C3 = 1000µF, 25V. Note 5: For all applications using greater than 13 LEDs a 330µF, 63V output capacitor (C3) was used. 5 www.national.com AN-2061 Output Current versus Number of LEDs for Various Modifications AN-2061 Typical Performance Characteristics Efficiency vs. Line Voltage Original Circuit Power Factor vs. Line Voltage Original Circuit 30124602 30124604 Efficiency vs. Line Voltage Modification A Power Factor vs. Line Voltage Modification A 30124611 30124612 Efficiency vs. Line Voltage Modification B Power Factor vs. Line Voltage Modification B 30124613 www.national.com 30124614 6 AN-2061 PCB Layout 30124610 Top Layer 30124609 Bottom Layer Warning: The LM3445 evaluation boards have no isolation or any type of protection from shock. Caution must be taken when handling evaluation board. Avoid touching evaluation board, and removing any cables while evaluation board is operating. Isolating the evaluation board rather than the oscilloscope is highly recommended. 7 www.national.com AN-2061 EMI/EMC Information 30124615 Radiated EMI 30124616 Conducted EMC. Line = Blue, Neutral = Black. Frequency Quasi-peak Amplitude Quasi-peak Limit Quasi-peak Delta Average Amplitude Average Limit Neutral 154 kHz 57 66 -9 47 56 -9 Line 1.1 MHz 31 46 -15 www.national.com 8 Average Delta AN-2061 Notes 9 www.national.com LM3445 A19 Edison Retrofit Evaluation Board Notes For more National Semiconductor product information and proven design tools, visit the following Web sites at: www.national.com Products Design Support Amplifiers www.national.com/amplifiers WEBENCH® Tools www.national.com/webench Audio www.national.com/audio App Notes www.national.com/appnotes Clock and Timing www.national.com/timing Reference Designs www.national.com/refdesigns Data Converters www.national.com/adc Samples www.national.com/samples Interface www.national.com/interface Eval Boards www.national.com/evalboards LVDS www.national.com/lvds Packaging www.national.com/packaging Power Management www.national.com/power Green Compliance www.national.com/quality/green Switching Regulators www.national.com/switchers Distributors www.national.com/contacts LDOs www.national.com/ldo Quality and Reliability www.national.com/quality LED Lighting www.national.com/led Feedback/Support www.national.com/feedback Voltage References www.national.com/vref Design Made Easy www.national.com/easy www.national.com/powerwise Applications & Markets www.national.com/solutions Mil/Aero www.national.com/milaero PowerWise® Solutions Serial Digital Interface (SDI) www.national.com/sdi Temperature Sensors www.national.com/tempsensors SolarMagic™ www.national.com/solarmagic PLL/VCO www.national.com/wireless www.national.com/training PowerWise® Design University THE CONTENTS OF THIS DOCUMENT ARE PROVIDED IN CONNECTION WITH NATIONAL SEMICONDUCTOR CORPORATION (“NATIONAL”) PRODUCTS. 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