APPLICATION NOTES: Using DomiPlus As LED Light Source For T8/T10 Tube Light. Introduction: LED T8/T10 Fluorescent replacement light tube has commonly available in the market since last two years. There are various types of LED package use for this LED T8/T10 tube. The 2 most common type of LED package used are: (i) 3528 type LED with typical power of 60mW per LED and (ii) 5050/6060 type LED with typical power of 0.5W or 1W Nevertheless, there are both pro and cons of using these 2 types of LED in T8/T10 application: 3528 Package Pro Cons 1 High optical efficiency 1 2 Wide spread of LED distribution across the pcb to enhance heat dissipation 2 3 Since quantity of LED use is huge, there is less bright spot observed on the tube 3 Usually 250/300 pieces of LED is required, substantial SMT cost and LED packaging cost Complicated pcb track design, imbalance current flowthrough each parallel string of LED might cause thermal runaway Left little space on the pcb board to mount other electronic component. 5050/6060 Package Pro Cons 1 Use up to 36 piece of LED only, save packaging and SMT cost 1 Obvious bright spot on LED tube due to high intensity point light source 2 Simple pcb and LED driving circuit design 2 Shadowing effect due to LED is widely space from one to another 3 Ample space on the pcb to slot in other electronic component 3 Challenging heat management due to localize point heat source 13/04/2010 -1- Proprietary information. All rights reserved VerO DomiPlus In T8/T10 Light Tube In order to gain advantage of 3528 package while filling in the short fall, Dominant has introduced DomiPlus LED package with the following features for light tube application: Typical drive current of 60mA (200mW). Electrically isolated terminal for simple heat sinking. High optical efficiency. Large light emitting surface. Optical Design Consideration For T8/T10 Light Tube Typically for the LED T8/T10 light tube, 308 pieces of 3528 LED is used in the design with total flux output of about 1600 lumen. Based on this calculation, the same total flux output can be achieved by using only 104 pieces DomiPlus LED, which is 66% reduction in LED count. The T8 light bar can be designed by using DomiPlus with a LED to LED pitch of 11.2mm in a 1.2m length T8 light bar application. The LEDs are arranged in a 2 rows formation to ensure more uniform light output from both sides of the light tube. A probable lay-out is as per illustrated below. This application note will demonstrate the performance of DomiPlus versus current typical designs. The DomiPlus design was compared with the following: (i) A standard 36W fluorescent lamp (ii) A LED T8 light tube with 308 pieces 3528 LED ( frosted cover ) (iii) Newly develop T8 light tube with 104 pieces DomiPlus LED ( frosted cover ) 13/04/2010 -2- Proprietary information. All rights reserved VerO DomiPlus In T8/T10 Light Tube Light Tube Measurement Setup 1.95m -100cm -77.5cm -55cm -22.5cm 0cm 22.5cm 55cm -35cm 0cm N ote 77.5cm 35cm Lux m easurem ent point 100cm 1. Reference: Measurement Of Standard 36W Fluorescent Lamp Height: 1.95m Lux Meter : Point Center 337 Mini Lightmeter . -100cm . -77.5cm . -55cm . -22.5cm Date 55cm 1/4/2010 0 22.5cm 77.5cm 100cm . -35cm 60 65 67 67 63 67 67 65 60 0 61 69 72 73 68 73 72 69 61 . +35cm 59 68 71 72 68 72 71 68 59 Photo Overview 13/04/2010 Close-up view -3- Proprietary information. All rights reserved VerO DomiPlus In T8/T10 Light Tube 2. Measurement Results Of Light Tube With 308 Pieces 3528 LED (Frosted Tube) Height: 1.95m Lux Meter : Point Extech Easy View 31 (LUX) . -100cm . -77.5cm . -55cm . -22.5cm 0 22.5cm Date 55cm 1/21/2010 77.5cm 100cm . -35cm 82 87 97 103 103 104 98 87 82 0 84 92 102 109 109 109 102 92 84 . +35cm 82 89 97 106 103 106 99 89 82 Overview Overview Close-up view 3. Measurement Results Of Light Tube With 104 Pieces DomiPlus LED (Frosted Tube) Height: 1.95m Lux Meter : Point Center 337 Mini Lightmeter . -100cm . -77.5cm . -55cm . -22.5cm 0 22.5cm Date 55cm 5/4/2010 77.5cm 100cm . -35cm 76 80 88 97 102 97 88 81 76 0 78 83 95 102 106 102 95 83 77 . +35cm 76 82 93 101 102 101 93 82 74 Overview Close-up view Comment: The flux measurement above shows that the surface luminance of light tube build with 104 pieces of DomiPlus is comparable to light tube with 308 pieces of 3528 LED. The surface of frosted tube will show an alternate bright/dim pattern when using the 104 pieces of DomiPlus LED. This is only obvious upon close up. However, the bright spot is certainly less visible compares to 5050/6060 type high power LED as displayed below: 13/04/2010 -4- Proprietary information. All rights reserved VerO DomiPlus In T8/T10 Light Tube Overview Close-up view CRI Enhancement The CRI for light tube can also be enhanced by addition of amber light element. In this case, SpiceLED LED, SSA-NLD is used to introduce the amber light for color mixing. With this combination, the light output can achieve CRI of 80 and above. 4. Measurement Results Of Light Tube With 104 Pieces DomiPlus LED And 34 SpiceLED (Note: measured with fix power as cool white model) Height: 1.95m Lux Meter : Point Center 337 Mini Lightmeter . -100cm . -77.5cm . -55cm . -22.5cm 0 22.5cm Date 55cm 5/4/2010 77.5cm 100cm . -35cm 65 74 85 95 97 95 85 74 65 0 70 79 91 102 104 102 91 79 70 . +35cm 67 87 89 101 101 101 89 87 67 Overview Close-up view Thermal Design Consideration DomiPlus is designed with 2 NC pads for direct heat sink attachment. It is constructed in such a manner that the electrical current paths are separated from the thermal path. This allows design of standard dual side FR4 PCB with plated through copper via to achieve maximum thermal conductivity directly from the NC pad down to the rear side of the PCB. 13/04/2010 -5- Proprietary information. All rights reserved VerO DomiPlus In T8/T10 Light Tube The rear side of the PCB is typically covered with copper and the PCB is mounted onto the metal casing of the lighting unit. This significantly improves the thermal management and in turns the reliability of the LEDs. DomiPlus solder lead design PCB Cross Section Through Hole Copper Plated Via On PCB With standard 60mA per LED driving condition, the LED solder point temperature can be maintained at 45 deg C in an enclosed tube. With this enhanced LED thermal management, the LED light intensity can be maintained at >90% level during light up. 13/04/2010 -6- Proprietary information. All rights reserved VerO DomiPlus In T8/T10 Light Tube Summary DomiPlus LED is a highly cost effective solution for T8/T10 light tube application that possesses the strength of both 3528 and 5050/6060 package. Even though the color tone on the frosted casing might appear slightly uneven, it manages to eliminate the glaring bright spot as seen using 5050/6060 package while maintaining the illuminated surface brightness. 13/04/2010 -7- Proprietary information. All rights reserved VerO