Application Note - T8 Application Design Guide

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
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