ATM2412B SERIES TFT GRAPHIC MODULE VER1.1
3.2 The Characteristics Of LED Backlight
3.2.1 Electrical-Optical Characteristics Of LED Backlight
(Ta=25ºC)
Item
Forward Voltage
(1)(5)
Forward Current
(5)
Luminance
(3)
Uniformity
(2)
Chroma coordinate
Lifetime
(4)
Symbol
Vf
If
Lv
Δ
x
y
-
Vf = 5V
Condition
--
Vf = 5V
Vf = 5V
(Lvmin/Lvmax)%
Vf = 5V
Min
3
--
200
70%
0.26
0.28
-
Typ
5
206
250
75%
--
--
20000
Max
5.5
--
--
--
0.36
0.38
-
Unit
V
mA
cd/㎡
-
-
-
Hours
NOTE:
(1) Forward voltage means voltage applied to Pin21 & Pin22
(2)The luminance is the average value of 5 points,The measurement instrument is BM-7 luminance
colorimeter.The diameter of aperture is
Φ5mm
(3) Luminance when LCM displaying white color.
(4) Backlight lifetime means luminance value larger than half of the original after 20000 hours’ continuous
working.
(5) Input current of Pin 21 might change because the voltage of PIN21 will affect the efficiency of backlight
driving circuit, but current for LEDs will keep constant within the range of input voltage.
3.2.2 Backlight Control Circuit For LCM（2x6=12 pcs LED）
B L D R IV IN G
C IR C U IT
2 2 :0 V
2 1 :+ 3 V ~ 5 .5 V IN
P IN 2 2 is c o n n e c te d to P IN 2 (V S S ) in te rn a lly
3.2.3 LED Characteristics Curves（for single led）
1.Forward current VS.Ambient Temperature
2.
Forward
current VS Forward Voltage
25
Forward Current (mA）
30
C u r r e n t ( m A )
F o r w a r d
20
15
10
5
0
-30
25
20
15
10
5
0
4
2
3
Forward Voltage
5
0
25
50 80
Ambient Temperature
100
AZ DISPLAYS
4
AZDISPLAYS [ AZ DISPLAYS ]
