LQ170E1LG11 Datasheet, PDF (12/23 Pages) Sharp Electrionic Components – TFT LCD MODULE

9
6-2. Backlight
The back light system is an edge-lighting type with 4CCFTs (Cold Cathode Fluorescent Tube).
The characteristics of the lamp are shown in the following table.
The value mentioned below is at the case of one CCFT.
CCFT Model Name : TBD
Parameter
Symbol Min. Typ. Max. Unit
Remark
Lamp current range
IL
(3.0) (6.5) (7.0) mArms Note1
Lamp voltage
V_L
Lamp power consumption PL
(650) (720) Vrms IL=(6.5)mArms Ta=25 (60)kHz
(4.23) (4.68) W
Note2
IL=(6.5)mArms Ta=25 (60)kHz
Lamp frequency
FL
(40) (60) (70) kHz Note3
Kick-off voltage
Vs
(1800) Vrms Ta=0 Note4
Lamp life time
TL (50,000)
hour Note5
Note1 A lamp can be light in the range of lamp current shown above.
Maximum rating for current is measured by high frequency current measurement equipment
connected to V_LOW at circuit showed below.
(Note : To keep enough kick-off voltage and necessary steady voltage for CCFT.)
Lamp frequency : (40) (70)kHz
Ambient temperature : 0 50
M odule
CN2,3,4,5
:1pin
CN2,3,4,5
:2pin
Inverter
Note2 Referential data per one CCFT by calculation ( IL
The data don’t include loss at inverter.
VL ) .
Note3 Lamp frequency of inverter may produce interference with horizontal synchronous frequency, and
this may cause horizontal beat on the display. Therefore, adjust lamp frequency, and keep inverter as far
as from module or use electronic shielding between inverter and module to avoid interference.
Note4 It is defined at 27pF for the ballast capacitor of a DC-AC inverter.
The kick-off voltage may rise up in the user set, please decide the open output voltage by checking not
to occur lighting failure under operating state.
The open output voltage should be applied to the lamp for more than 1 second to startup.
Otherwise the lamp may not be turned on.
Note5 Above value is applicable when the long side of LCD module is placed horizontally.
(Landscape position)
(Lamp lifetime may vary if LCD module is in portrait position due to the change of mercury density
inside the lamp.)
Lamp life time is defined as the time when either or occurs in the continuous operation under
the condition of Ta=25 and IL=(6.5) mA rms.
Brightness becomes 50% of the original value under standard condition.
Kick-off voltage at Ta=0 exceeds (1800) V_rms value.
Note
The performance of the backlight, for example lifetime or brightness, is much influenced by the characteristics of
the DC-AC inverter for the lamp. When you design or order the inverter, please make sure that a poor lighting
caused by the mismatch of the backlight and the inverter (miss-lighting, flicker, etc.) never occurs. When you
confirm it, the module should be operated in the same condition as it is installed in your instrument.
Use the lamp inverter power source incorporating such safeguard as overvoltage / overcurrent protective circuit
or lamp voltage waveform detection circuit, which should have individual control of each lamp.
In case one circuit without such individual control is connected to more than two lamps, excessive current may
flow into one lamp when the other one is not in operation.