for Design Guide T8 Application Samsung Electronics LM561X, LM231X rev1.0 1. Introduction 2 1.1 T8 Description 3 1.1.1 Fluorescent 3 1.1.2 The structure of LED-tube 4 1.1.3 The effects of diffuser 5 1.1.4 The effects of pitch 6 1.1.5 Ballast connection of LED-tube 7 2. Implementation 8 2.1 T8 Implementation 8 2.1.1 Calculation table (estimation) 8 2.1.2 Implementation (realization) 9 2.1.3 Comparison with estimation vs. realization 9 3. Epilogue 10 4. Revision History 11 With incandescent lamp, fluorescent lamp has become a main lighting source of residential life and industrial filed. For energy savings and protection of the environment, new light source has to be required and LED is a major candidate of replacing that role. In this design guide, it is shown how LED component could be used as the lighting source of these traditional lamp and what main design factors are. Especially samsung LED components, LM5631X, LM231X, are introduced as a light source and several technical guide is presented in terms of thermal and optical properties. T8 specification could be designed - total luminous flux, power dissipation, beam angle and the number of LEDs. From these specification, expected performances could be estimated through the design support tool. For accuracy, we made entire T8 LED-tube implementation and showed comparison with estimated performance and realized results. This design guide is made for providing several design information for T8 LED-tube replacement and is not any warranty or a specification. 2 1.1 T8 Description 1.1.1 Fluorescent Visible light Glass tube Phosphor UV rays Electron Reflector Fluorescent Hg & Ar gas Filament AC power input consent Starter Condenser Switch Ballaster Lighting [ Fluorescent structure & circuit ] [ 360′ beam angle & reflector ] Fluorescent has developed nearly 60 years ago and nowadays so many lighting application adopted this light source. Brief theory is that electrons emitted from filament meets Hg & Ar gas and then generate UV rays which makes visible light with phosphor coated inside of glass tube. Less optical glare is a great merit of fluorescent. On the other hand, adopted Hg and Ar gas is anti-ecologies and normally reflector which could reduce efficiency of system is basic essential combination for it’s 360 beam angle features. Bi pin Single pin Double contact Base (Socket) Tube (Diameter /Length) Application G5 G13 Fa8 R17d T-5 (16㎜ / 2ft) T-8 (26㎜ / 2ft, 4ft, 8ft) T-10 (32㎜ / 2ft, 4ft, 8ft) T-12 (38㎜ / 2ft, 4ft, 8ft) T-6 T-8 T-12 T-10 T-12 Regular type High output / Very high output [ Fluorescent socket type & tube diameter ] Fluorescent has several different pin type. G13 socket is largely used in T-8, T-10 and T-12. G5 is used in T-5 which has higher optical efficiency rather than T-8 due to shorter diameter. Single pin and double contact pin is used partially. 3 1.1 T8 Description 1.1.2 The structure of LED-tube LED-tube have begun to replace fluorescent light source for high optical efficiency, energy saving, eco-friendly material and long lifetime. Especially as for LED-tube’s long lifetime, demand of LED-tube has been requested from garage lighting application of large market and storage. After early time, many indoor application start to replace fluorescent lamp with LEDtube as a main lighting source. Reflector Fluorescent Diffuser cover Cap LED PCB Heat sink Lighting FR-PCB LED Diffuser cover PSU Heat sink [ Structure of LED-tube ] General structure of the LED-tube consists of LED, PCB, heat sink, diffuser cover, socket and power supply unit(PSU) instead of ballast in fluorescent. LED emit optical light directionally, therefore actually reflector doesn’t be required as much as fluorescent lamp. This makes LEDtube has less optical loss rather than fluorescent. But LED-tube needs function of scattering directional light characteristics through the diffuser cover which could reduce glare property also. 4 1.1 T8 Description 1.1.3 The effects of diffuser LED has a directional optic property and needs to adopt heat sink, large PCB which makes longish beam angle of T8. In order to increase viewing angle more wider, diffuser cover could be used and additionally this cover also makes less glare level. Heat Sink PCB LED Diffuser Lighting Lighting [ Without diffuser cover ] [ With diffuser cover ] shadow Diffusion of light Heat sink Without diffuser cover Diffuser With diffuser cover [ The difference of beam angle between without and with diffuser @ side view ] In above picture, we can observe shadow line from heat sink edge (without diffuser) and also could see more wide diffused light performance (with diffuser). 5 1.1 T8 Description 1.1.4 The effects of LED pitch There are some relations between LED pitch and cover height from LED to diffuser for illuminance uniformity. If LED power consumption is increased to emit higher luminance flux, heat sink might be designed more carefully and could be appeared hot spot through diffuser cover (Case-C). To prevent hot spot, the height of diffuser cover should be larger and the diameter should be considered by T8 specification (Case-D). To reduce cover diameter of LED-tube, LED pitch and LED light output should be optimized to T8 system and then thermal management should be optimized (Case-A or Case-B). The index of illuminance uniformity ratio could be presented in terms of MH value. Heat Sink P-1 Heat P-2 P-3 PCB H-1 H-2 LED H-3 Light Diffuser (side view) Diffuser (top view) Uniform intensity (Case – A) (Case – B) Hot spot intensity Uniform intensity (Case – C) (Case – D) 0.8 Height : 16.8mm 0.7 (minimum / maximum) Uniformity ratio of illuminance [ The relation of pitch and cover height for illuminance uniformity ] 0.6 Pitch : 10.8mm Targeting uniformity Minimum uniformity 0.5 0.4 0.3 2nd optic design is required region 0.2 0.1 0 1 2 3 4 5 6 7 8 9 10 MH (Length of LED-diffuser cover / Pitch of LED-LED) MH = (Height / Pitch) = 1.55 [ Uniformity ratio of illuminance] 6 1.1 T8 Description 1.1.5 Ballast connection of LED-tube Traditional fluorescent lamp is driven by ballast which is divided into magnetic ballast and electronic ballast. The work of these ballast is AC charging and discharging not the conversion of AC to DC power(SMPS). But LED –tube should be driven by constant current mode. Therefore AC to DC power converter is generally required as a ballast of LED-tube. At first, for the compatibility between already installed magnetic or electronic ballast of traditional T8 lamp and LED-tube, compatible converter should be required for LED-tube. LED-tube Starter LED driver Electronic Ballast Magnetic Ballast [ compatible converter type with installed ballast of fluorescent ] The exclusive converter for LED-tube is divided into interior type and exterior type. Interior converter type is embedded in LED-tube body and tube socket is connected to AC plug directly. And another is exterior type which is separated with LED-tube body like as fluorescent ballast. [ Interior converter type ] [ Exterior converter type ] 7 2.1 T8 Implementation 2.1.1 Calculated table (estimation) System estimation and compare tool of samsung led is supported for user convenience. First, user could sellect LED type and detail rank information (CCT, VF, Flux rank). Then optical and electrical efficiency of system information could be inserted. If there’s non information of system level, then just board level results might be shown. Second, target driving current and the number of LEDs should be inserted. After this, unit LED performance(Flux, VF) and system expected value(total flux, power consumption, lumen per watt) could be shown. And this value is just only relevant to 25℃ solder point temperature case(Ts). If user want real value at operating condition, for example when Ts is 70℃ or 85℃ etc,. do the next stage. Third, insert expected Ts temperature to tool. Then LED performance might be changed as to inserted Ts information and system results might be changed also. Furthermore the thermal resistance of system could be known. From these system information, allowable current level related with derating curve is shown and some comments would be presented and expected lifetime becomes to be shown. LM231A sellect : LM231A,LM231B,LM561A,LM561B,LM362A CCT [K] 2700 B 5000 C 5000 2700~6500 IF_driving (A) # of LED Vf : AZ,A1,A2,A3,A4 A3 (Datasheet) TJ_max. = 110℃ Rank Flux : S1,S2,S3 S2 (Datasheet) IF_max. = 150㎃ LED performances at operating 2700 5000 5000 2700~6500 Derating performance Flux (㏐) TJ (℃) Flux (㏐) Power (W) Efficacy (Lm/W) Rth(J-a) 2.95 20.4 54.3 1997 23.30 85.7 256 110 51 25 0.063 22.7 58.7 2020 23.99 0.150 inside of derating curve 100 55 25 84.2 258.2 0.087 inside of derating curve 90 59 25 2.99 25.2 63.2 2019 24.50 82.4 256.1 0.150 0.079 inside of derating curve 110 51 25 2.95 20.9 54.3 2046 23.30 87.8 256 0.150 0.094 inside of derating curve 0.100 110 75 25 3.05 34.8 81.1 3407 43.01 79.2 255.5 0.150 0.050 inside of derating curve 0.150 110 105 25 3.13 46.2 114.4 4523 66.21 68.3 255.6 0.143 -0.007 Out of current range 0.056 110 64 25 2.92 20.4 67.3 1997 23.06 86.6 373.1 0.113 0.057 inside of derating curve 0.100 110 99 25 2.99 32.2 105.0 3152 42.17 74.7 371.5 0.106 0.006 Warning for current 0.114 110 111 25 3.03 36.0 117.9 3524 48.71 0.04~0.15 Input # Efficiency of PSU 0~100 78% Efficiency of Optical 0~100 89% measured data LED performances at operating 0.150 Comment 0.094 0.056 IF_driving (A) # of LED 2.97 IF_max. (A) IF_margin (A) 0.071 Input filed CCT [K] Estimations of system VF (V) 0.056 CASE F LED 89% Ta (℃) sellect : LM231A,LM231B,LM561A,LM561B,LM362A E 78% 0~100 Ts (℃) LM561B D 0~100 Input filed CASE A Efficiency of PSU Efficiency of Optical 72.3 370 0.104 -0.010 Out of current range ※ derating characteristics is based on Ts (LED solder temperature) ※ IF_margin = IF_max.-IF_driving LED Vf : AZ,A1,A2,A3,A4 A3 Rank Flux : S1,S2,S3 S2 Estimations of system (Datasheet) TJ_max. = 110℃ (Datasheet) IF_max. = 150㎃ Derating performance Ts (℃) Ta (℃) VF (V) Flux (㏐) TJ (℃) Flux (㏐) Power (W) Efficacy (Lm/W) Rth(J-a) 0.056 110 52 25 2.96 22.4 54.7 2193 23.38 93.8 258.2 0.150 0.094 inside of derating curve 0.063 100 56 25 2.98 24.9 59.0 2216 24.07 92.1 259.3 0.150 0.087 inside of derating curve 0.071 90 60 25 3.00 27.7 63.4 2219 24.58 90.3 256.3 0.150 0.079 inside of derating curve 0.056 110 52 25 2.96 24.9 54.7 2438 23.38 104.3 258.2 0.150 0.094 inside of derating curve 0.100 110 77 25 3.07 41.0 81.9 4014 43.29 92.7 257.5 0.149 0.049 inside of derating curve 0.150 110 109 25 3.18 56.0 116.6 5482 67.27 81.5 257.9 0.139 -0.011 Out of current range 0.056 110 65 25 2.94 24.3 67.6 2379 23.22 102.5 373.8 0.112 0.056 inside of derating curve 0.100 110 102 25 3.03 39.0 106.8 3818 42.73 89.4 375.2 0.104 0.004 Warning for current 0.114 110 115 25 3.07 43.7 120.6 4278 49.36 86.7 375.7 0.101 -0.013 Out of current range 0.04~0.15 Input # measured data 8 IF_max. (A) IF_margin (A) Comment 2.1 T8 Implementation 2.1.2 Implementation (realization) Real implementation of LED-tube is made for 4ft T8 replacement. Adopted LED components are LM561B and LM231A and 110 number of LEDs are used respectively. 2.1.3 Comparison with estimation vs. realization The measured value of LED-tube implementation and the estimated value from estimation software tool is compared as below table. LED Rank (VF : A3, Flux : S2) LM561B Estim. LM231A Imple. Estim. Imple. LM561B Estim. LM231A Imple. Estim. CCT (K) 2700 5000 # of LED 110 110 Total lumen (lm) 2193 Total power (W) 23.4 Set efficacy (lm/W) 93.8 2242 1997 (102.2%) 23.9 (99.8%) 23.3 (102.1% 93.8 1994 23.8 (102.1%) 85.7 (100.0%) 83.8 (97.8%) ※( 2438 2442 (100.2%) 23.4 23.5 (100.4%) 104.3 104.1 (99.8%) 2046 Imple. 2162 (105.6%) 23.3 24.0 (103.0%) 87.8 90.2 (102.7%) ) : ratio of ‘implementation value / estimation value’ 9 The market price of LED-tube falls down rapidly year by year. But actually the cost of LEDtube is still expensive compared with fluorescent lamp. Therefore manufacturer should consider 2 kind of main factor. One is initial price of LED-tube itself and install cost. Another is running cost related with electric bill and this cost is closely correlated with LED-tube efficiency. From these relations, the concept of payback becomes important. Below graph show a simple payback curve. Both of A-condition and B-condition has same initial price. But LED-tube efficiency or electric bill might be different. Therefore payback time could be different like as below graph(payback A-point and B-point, the efficiency of B is more higher than A). Surely as initial cost falls down, payback time could be advanced like B’-condition. Therefore LED-tube could have various market positioning according to each country and installed site . Total cost Fluorescent Initial cost + Running cost LED-tube (A-condition) Payback A-point Payback B-point Payback B’-point LED-tube (B-condition) LED-tube (B’-condition) Time [ Example of payback] 10 Writer Date Revision History 2013.03.21 New Version 11 Drawn Approved Y.J. Lee D.M. Jeon