AND8463/D 11 Watt TRIAC Dimmable PAR30 LED Lamp Driver Prepared by: Jim Young ON Semiconductor http://onsemi.com APPLICATION NOTE well as electrical requirements for integrated driver within the bulb. One of the key requirements which applies to all bulbs that draw more than 5 watts of power is that the power factor be ≥0.70 and the driver must meet specific FCC EMI requirements. While not mandated, dimming is a key end market requirement for many uses and is one of the reasons that CFL bulbs have not had broader acceptance in this bulb style where halogen and traditional incandescent are the norm. The standard requires that for those bulbs that are line dimmable via a wall dimmer, either leading edge (TRIAC) or trailing edge (transistor based), that the vendor clearly label whether the bulb is dimmable or not and provide a list of compliant dimmers that work with the LED bulb. One other consideration, since LEDs require a heatsink to remove the heat from the LED, the driver should normally be galvanically isolated. Parabolic Aluminized Reflector (PAR) lamps are one of the most popular bulb types for downlighting, retail, and spot light applications. They range in size from PAR16 to PAR64. The number indicates the diameter in 1/8” units so a PAR30 lamp would have a diameter of 3.75” (9 cm). Other variants of these directional lamps include R and BR styles. Given that the light pattern of these types of bulbs is directional in nature, they are ideal candidates for LED light sources. In addition, since PAR lamps are offered in various beam widths, changing secondary optics on the LEDs can result in a range of product types from spot to flood. The US ENERGY STARt program has just completed their standard for Integral LED bulbs which will go into effect August 31, 2010. These specifications are comprehensive and include items such as minimum light output requirements, efficacy, acceptable correlated color temperatures, dimming considerations, and warrantee as Figure 1. PAR30 LED and Incandescent Lamps © Semiconductor Components Industries, LLC, 2010 July, 2010 − Rev. 1 1 Publication Order Number: AND8463/D AND8463/D Details for a 115 and a 230 V ac input version are presented in this Application Note. Here are the design goals: • 115 V Lamp Input Voltage: 90 – 135 V ac Power Factor: >0.9 Input current THD: <20% • 230 V Lamp Input Voltage: 180 - 265 V ac IEC 61000−3−2 Class C compliant • LED power: 11 watts • LED current: 450 mA • LED current accuracy: +/- 5% • LED voltage: 21 – 27 V dc • Efficiency: >82% • Compatible with TRIAC and Electronic Low Voltage Dimmers • Compliance with FCC Class B conducted emissions The circuit design, component selection, and layout of the reference board were based on general safety guidelines although the design has not been submitted to a safety ratings agency for formal review. A printed circuit board outline extending from the bottom of the E27 base to the LED mounting plate was chosen. The irregular outline matches the interior space of the selected heatsink and base assembly. Component placement and circuit routing is critical to provide adequate voltage spacing. The PCB and lamp assembly is shown in Figures 2, 3, and 4 below: This Application Note details how the NCL30000 single stage power factor corrected isolated flyback controller can be used to implement a complete power conversion solution. This design shown in Figure 1 above is adapted from the ON Semiconductor NCL30000 LED driver demonstration board with a range of changes to optimize the design for a well defined LED load. A commercially available LED heatsink assembly and E27 Edison base housing were used. CREE’s MPL-EZW LED module was selected as the light engine. The LED module electrical connections and mechanical securement are made with the Tyco Electronics TE solderless LED socket 2106946-2. This connector provides a clean and efficient interface to the LED. This multi-LED module has 24 LEDs arranged in 3 strings of 8. The LEDs are configured in a series-parallel arrangement with a nominal drive current of 450 mA (150 mA per string). Other LEDs can be used as well but the ultimate limitation to the PAR form factor is the thermal heatsinking of the housing and the expected end application environment. The size of the PAR30 envelope is well defined and the primary objective in this design is to provide as much power as possible to the LEDs while achieving high energy conversion efficiency. Initial Design Space inside the housing is limited and the general solution presented in the NCL30000LED1GEVB demonstration board will be modified towards the specific requirements of an 11 watt TRIAC dimmable LED lamp. Figure 2. http://onsemi.com 2 AND8463/D Figure 3. Figure 4. http://onsemi.com 3 AND8463/D Detailed Design applications whereas the 230 V application requires an 800 V FET. Likewise, a 100 V Schottky rectifier is appropriate for 115 V applications and a 200 V device was chosen for 230 V lamps. A turns ratio of 5.3 to 1 will function well with both input ranges. The minimum operating frequency will change depending on the input voltage. Frequency is sufficiently low for the EMI filter to accommodate either range. Safety isolation requires triple insulated wire where 21 turns of #26 wire fills one layer. Splitting the primary in two equal series-connected segments with the secondary positioned in between will provide low leakage inductance. In this case, 56 turns per primary section are used. The bias winding must provide sufficient power to maintain operation when connected to a phase cut dimmer. Empirical testing shows 17 to 20 volts minimum works well. A bias winding of 16 turns ensures adequate voltage. The transformer primary inductance is 1.9 mH. Secondary bias can be simplified due to the lower LED forward voltage. In this case, the regulator transistor can be eliminated utilizing resistor R21 and zener D11 to establish bias voltage. Further reduction in parts is possible in this dimming application compared to a non-dimming application. Since the load is well defined and the line voltage is restricted, the maximum on-time capacitor limits the peak power delivered such that the ’fast’ current control loop utilized on the NCL30000LED evaluation board can be eliminated. The NCS1002 dual op-amp plus reference replaces the dual op amp and separate reference. The op-amp connected directly to the reference provides open load protection and the second op-amp is the LED current regulator. The 0.2 ohm sense resistor keeps sensing losses to a minimum. The schematic for the 115 V driver is shown in Figure 5 below. A complete bill of material is shown in Appendix A at the end of this Application Note. Complete design details for the NCL30000 are presented in Application Notes AND8451 and AND8448. The 11 watt power level is close to the 15 watt operation of the demonstration board. As such, a similar EMI filter will be used for this PAR30 design. The MOV surge limiter is relocated across the input line for better circuit board placement and to limit energy dissipated in the input resistors R1 and R10. These input resistors are included for TRIAC compatibility along with R4 and C3. The component values depend on the input voltage range. Designing for a narrow output voltage range allows some simplifications to the original schematic, in particular, the biasing networks. For dimming, the input waveform will be chopped and the bias capacitor must store energy during the active input periods and deliver bias power to the NCL30000 during periods when the input is not present. The narrow LED operating range allows elimination of electrolytic capacitor C6. C8 is required for energy storage and Q2 is needed to improve efficiency of regulator zener diode D9. Biasing for optocoupler U2 is provided by D8 and R14 without affecting the low current start up energy provided by R7 and R13. Turn on time is controlled by R7 and R13. Reducing the value of these resistors will speed turn on delay but will adversely affect efficiency. Setting the resistance too high will result in insufficient current for the base of Q2 and will limit bias power at low dimming settings. Selecting R7 and R13 as 47K ohms provides turn on delay of 240 msec for the 115 V lamp and 150K ohms provides 290 msec for the 230 V lamp and performs well when dimming. An EFD20 transformer core is used which fits the limited volume inside the housing. The NCL30000 Design Spreadsheet is used to establish transformer parameters. The process begins with entering the input voltage range and LED output parameters. A 500 V FET is sufficient for 115 V http://onsemi.com 4 D9 MMBZ5245 15V N RV1 V275LA2 15 Ohm C7 1nF R14 4.7K D8 MMBZ5239 9.1v R13 47K R7 47K R1 R10 0 Ohm R2 C1 470pF 5K6 R9 6.2K R15 100K C2 47nF 5K6 C9 470pF 4 3 2 1 U1 - + ZCD GND DRV Vcc NCL30000 CS Ct Comp MFP MMBTA06 Q2 L3 1.6mH R3 4 D1 HD06 1 2 L2 800uH 5 6 7 8 C3 470nF 3 Ca 100pF Rb 10K Ra 2.2K Da MMBD7000 D6 BAS21 C4 100nF C8 10uF R4 240 10 R18 R20 0.5 OHM 100 Q3 NDD05N50Z R19 Optional Minimum off-time circuit R16 47K D5 MURA160 C5 4700 pF 8 FL2 T1D FL1 C10 4.7 nF U2 PS2561L_1 6 T1C 7 4 T1B 3 9 T1A 4 5 3 http://onsemi.com 1 Figure 5. 115V Lamp Schematic 2 L + 3mA C11 680uF D10 MBRD5H100 R22 1.5K D11 MMBZ5231 5.1V C13 100nF R21 3.3K 100pF C14 R31 4.7K R25 2.2K R27 51K 1 2 3 4 R26 18K U3 NCS1002 8 7 6 5 R28 680 D13 BAW56 0.2 ohm R29 LED+ R30 24K LED- C15 220nF R8 47K 24.4Volts AND8463/D AND8463/D Performance Results Data shown below in Table 1 was collected from each version of PAR30 lamp. The damper network comprised of R4 and C3 improves performance when a TRIAC dimmer is used. This network dissipates energy and introduces some phase displacement on input current. If dimming is not required, the damper network can be eliminated. Performance for each configuration is shown below: Table 1. Performance of PAR30 Lamps Lamp Version RC Damper Present Input Power (W) PF %THD Output Current (mA) Output Volts (Vdc) Output Power (W) Efficiency (%) 115 Yes 12.91 0.98 10.2 452 23.61 10.67 82.7 No 12.72 0.99 6.5 452 23.60 10.67 83.9 Yes 13.00 0.87 23.4 453 23.60 10.69 82.2 No 12.59 0.97 11.2 453 23.44 10.62 84.4 230 As with any high power factor single stage converter output ripple is filtered by the secondary side capacitor. LEDs display a constant voltage characteristic and current ripple is sensitive to the driver’s output ripple voltage where higher capacitance minimizes ripple. Space is limited in this application and a 680 mF capacitor was selected as the output filter. Ripple current is shown in Figures 6 and 7 below. Scale factor is 167 mA/division: Figure 7. 393 mA pk-pk ripple current for 230V Lamp The peak of the ripple current is maintained below the maximum operating current of the LEDs selected. Thermocouples were affixed to critical components and the driver was enclosed in the lamp housing with the heatsink attached in its expected configuration. LED temperature was monitored on the aluminum base plate adjacent to the LED module. The lamp was operated until thermal equilibrium was achieved. Results are shown in Table 2 below: Figure 6. 320 mA pk-pk ripple current for 115V Lamp Table 2. Thermal Test Results Ambient LEDs Q3 FET D10 Output Rectifier Transformer C11 output capacitor 17.8°C 56.9°C 75.2°C 82.0°C 72.4°C 57.8°C Temp Rise 39.1°C 57.4°C 64.2°C 54.6°C 40.0°C In a production integral LED lamp it is common to have the power supply assembly encapsulated in a potting compound. Potting will improve thermal transfer and reduces hot spot temperatures. http://onsemi.com 6 AND8463/D IEC61000-3-2 Current Harmonics Dimming Performance The design passes Class C current harmonic requirements for both 115 V and 230 V versions. Test results are shown below in Table 3. Note these lamps also pass the more stringent requirements for inputs equal to or greater than 25 watts. The PAR30 LED lamp performs well with a variety of commercially available TRIAC and electronic phase cut dimmers. Dimming is continuous and predictable with many dimmers providing control down to zero light output. Table 4 below shows 115 V and Table 5 shows 230 V PAR30 lamp performance with various dimmers. Table 3. Class C Current Harmonics Lamp version 3rd Harmonic (Limit 86%) 5th Harmonic (Limit 61%) 115 5.94% 3.36% 230 16.6% 10.96% Table 4. 115 V Version Lamp Dimmer Performance Manufacturer Dimmer Model Min Conduction Angle (degrees) Current at Min Conduction Angle (mA) Cooper Aspire 9530AA 9.9 1 Ding Chung DC-310 9.1 5 GE Rotary DI 61 <10.4 <1 Kuei Lin AC 110V 500W <9.1 <1 Leviton CFL Slide 6673-P 33.9 57 Leviton Electronic 6615-POW 56.6 116 Leviton Illumatech IPI06 16 11 Leviton Rotary OC58L1 <11 <2 Leviton Sureslide 6633-PLW <11 <1 Lutron Digital Fade MAW-600H 13.6 17 Lutron Skylark S-600 <9.9 <1 Lutron Toggler TG-600PH 25.5 22 Pass & Seymour D703PLAV 8.6 <1 Pass & Seymour LS603PLAV 8.2 <1 Pass & Seymour LSLV603PWV <6.7 <1 SCT YM-2508A <8 <1 Table 5. 230 V Version Lamp Dimmer Performance Manufacturer Dimmer Model Min Conduction Angle (degrees) Current at Min Conduction Angle (mA) Alombard 741021 10 <1 Clipsal KB31RD400 12.6 <1 Clipsal 32V500 14 <1 Legrande 999.58 50 110 Lutron LLSM-502 9 3 MK SX8501 18.4 11 SCT Y-25082A 15 6 http://onsemi.com 7 AND8463/D Conducted EMI Minimizing ’across the line’ or X-capacitance will reduce current peaks when the TRIAC turns on. Oscillations in the input filter will be reduced and TRIAC operation is more predictable. Adding resistance in series with the input (R1 and R10) and an R-C damper (R4 and C3) reduce the oscillations as well. Figures 8 and 9 show the conducted EMI profiles for the 115 V and 230 V PAR30 lamps respectively. An input filter is necessary to meet Class B conducted EMI limits. The filter was carefully designed for compatibility with TRIAC dimmers since excessive current peaks when the TRIAC turns on will create oscillations in the filter. If this occurs, the resultant damped sinusoid input current can fall below the minimum TRIAC holding current forcing the TRIAC off prematurely. Depending on the TRIAC dimmer position and the line voltage the TRIAC could re-fire resulting in visible flicker and added component stress. dBuV 80 70 60 EN 55022; Class B Conducted, Quasi−Peak 50 EN 55022; Class B Conducted, Average 40 30 20 10 Average 0 −10 −20 1 10 (Start = 0.15, Stop = 30.00) MHz Figure 8. EMI Profile for 115 V Lamp dBuV 80 70 60 EN 55022; Class B Conducted, Quasi-Peak 50 EN 55022; Class B Conducted, Average 40 30 20 10 Average 0 −10 −20 1 10 (Start = 0.15, Stop = 30.00) MHz Figure 9. EMI Profile for 230 V Lamp Conclusion efficiency allows the thermally limited PAR30 envelope to deliver more power to the LEDs and consume less power in the driver. The basic design can be scaled up for higher power to support PAR38 lamps. A practical PAR30 LED lamp design based on the NCL30000 LED controller is presented which meets the design objectives. This circuit can be tailored to match drive requirements for many different LED engines. The high http://onsemi.com 8 AND8463/D APPENDIX A: Bill Of Materials Bill of Materials for the NCL300000 PAR30 Driver Note: Parts specific to one version of Lamp are indicated as (115V) or (230V). Designator Value Footprint Manufacturer C1 470pF 50V Ceramic COG, NPO 0603 SMD Panasonic ECJ-1VC1H471J C2 47nF 300 VAC Film X1 (LS = 12.5 mm) Box Panasonic ECQ-U3A473MG C3 (115V) 470nF 450 V Metal Polyester Film (LS = 15mm) Box EPCOS C3 (230V) 330nF 250 VAC Metallized Polyester Film (LS=15 mm) Box Panasonic ECQ-U2A334ML C4 100nF 250 VAC X1 Metal Polyester Film (LS = 15 mm) Box Panasonic ECQ-U2A104ML C5 4700 pF 500V Ceramic X7R 1206 SMD Vishay C7 1nF 50V Ceramic X7R 0603 SMD Panasonic ECJ-1VB1H102K C8 10uF 50V Electrolytic, 5mm dia (LS = 2mm) Radial Panasonic EEU-EB1H100S C9 (115V) 470pF 50V Ceramic COG, NPO 0603 SMD Panasonic ECJ-1VC1H471J C9 (230V) 180pF 50V Ceramic 0603 SMD Panasonic ECJ-1VC1H181J C10 4.7 nF 250VAC Y5U X1Y1 (LS = 10mm) Radial Panasonic CD16-E2GA472MYNS C11 680uF 35V Aluminum Electrolytic Radial Panasonic EEU-FM1V681 C13 100nF 25V Ceramic X7R 0603 SMD Panasonic ECJ-1VB1E104K C14 100pF 50V Ceramic COG, NPO 0603 SMD Panasonic ECJ-1VC1H101J C15 220nF 25V Ceramic X7R 0603 SMD Panasonic C1608XR1E224M HD06-T D1 HD06-T D5 MURA160 D6 BAS21 D8 D9 Description Manufacturer Part Number B32522N6474J VJ1206Y472KXEAT5Z Rectifier bridge, 600V, 0.8A SMD Diodes Inc. 600V, 1A SMA ON Semiconductor MURA160T3 250V, 200mA SOT23 ON Semiconductor BAS21LT1G MMBZ5239 9.1V ZENER SOT23 ON Semiconductor MMBZ5239BLT1 MMBZ5245 15V ZENER SOT23 ON Semiconductor MMBZ5245BLT1 MBRD5H100 Schottky, 100V, 5A DPAK ON Semiconductor MBRD5H100T4G D10 (230V) MURD620 Rectifier, 200V, 6A DPAK ON Semiconductor MURD620CT D11 MMBZ5231 5.1V ZENER SOT23 ON Semiconductor MMBZ5231BLT1 D13 BAW56 70V, 200MA SOT23 ON Semiconductor BAW56LT1G L2 800uH Torroid Through Hole Wurth Midcom L3 (115V) 1.6mH Torroid Through Hole Wurth Midcom L3 (230V) 800uH Torroid Through Hole Wurth Midcom D10 (115V) 750311431 Rev 6A 750311431 Rev 6A Q2 MMBTA06 NPN, 80V, 500mA SOT23 ON Semiconductor MMBTA06LT1G Q3 (115V) NDD05N50 N-Channel MOSFET 500V, 4.7A, 1.5R DPAK ON Semiconductor NDD05N50ZT4G Q3 (230V) SPD02N80 N-Channel MOSFET 800V, 2A DPAK Infineon SPD02N80C3 R1 (115V) 15 Fusible resistor, 1W Axial Vishay NFR0100001509JR500 R1 (230V) 33R Fusible resistor, 33R, 1W NFR0100003309JR500 R2 R3 5K6 1/10W R4 (115V) 240 Metal Film 1W Axial Vishay 0603 SMD Panasonic Axial Vishay http://onsemi.com 9 ERJ-3GEYJ562V PR01000102400JR500 AND8463/D Designator Value Description Footprint Manufacturer Manufacturer Part Number R4 (230V) 510 Metal Film 1W Axial Vishay PR01000105100JR500 R7 R13 (115V) 47K 1/4W 1206 SMD Panasonic ERJ-8ENF4702V R7 R13 (230V) 150K 1/4W 1206 SMD Vishay ERJ-8ENF1503V R8 47K 1/10W 0603 SMD Panasonic ERJ-3EKF4702V R9 6K2 1/10W 0603 SMD Panasonic ERJ-3EKF6201V R10 (115V) Zero Jumper - - R10 (230V) 33R Fusible resistor, 33R, 1W Axial Vishay R14 4K7 1/10W 0603 SMD Panasonic ERJ-3EKF4701V R15 100K 1/10W 0603 SMD Panasonic ERJ-3EKF1003V R16 47K 1/10W 0603 SMD Panasonic ERJ-3EKF4702V R18 100 1/10W 0603 SMD Panasonic ERJ-3EKF1000V R19 10 1/10W 0603 SMD Panasonic ERJ-3EKF10R0V R20 0.51 1/4W 1206 SMD Rohm R21 3.3K 1/4W 1206 SMD Panasonic ERJ-8ENF3301V R22 1.5K 1/10W 0603 SMD Panasonic ERJ-3EKF1501V R25 2.2K 1/10W 0603 SMD Panasonic ERJ-3EKF2201V R26 18K 1/4W 1206 SMD Panasonic ERJ-8ENF1802V R27 51K 1/4W 1206 SMD Panasonic ERJ-8ENF5102V R28 680 1/10W 0603 SMD Panasonic ERJ-3GEYJ681V R29 0.2 1/4W 1206 SMD Rohm Semi MCR18EZHFLR200 R30 24K 1/10W 0603 SMD Panasonic ERJ-3EKF2402V R31 4K7 1/4W 1206 SMD Panasonic ERJ-8ENF4701V RV1 V275LA2 275V 23 Joule (LS = 7mm) Radial Littelfuse U1 NCL30000 Single Stage PFC LED Driver SOIC8 ON Semiconductor U2 PS2561L_1 80V, 50mA SMT4 NEC Electronics U3 NCS1002 CV/CC Secondary Controller SOIC8 ON Semiconductor SMD EFD20 Wurth Midcom T1 EFD 20, 12 watt NFR0100003309JR500 MCR18EZHFLR510 V275LA2P NCL30000DR2G PS2561L-1 NCS1002DR2G 750311620 ENERGY STAR and the ENERGY STAR mark are registered U.S. marks. 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