- LED backlit modules are 2-5mm thicker than an EL or non-backlit
- Longer life ( more than 100,000 hours ) than EL lamps at the
sacrifice of power and module size.
- Operation is possible by the same +5 V supply as used for the
modules. (Standard color yellow-green)
- The LED backlight illumination is available in yellow-green,
green, white, red, and amber.
- The brightness of the backlight can simply be adjusted by a
resistor or a potentiometer
- In most cases, 1 lamp failing does not make the backlight unusable.
Using Methods of BKL
There are 5 methods of using LED in character type:
- This is the most common type to light the LED by external of
4.2V to Jp2 between pin 1 and pin 4.
- Lighting the LED through a limiting current resistance which
we already included in our LCM by external voltage of 5V to Jp2
between pin 1 and pin 4.
- Providing 4.2V by pin 15 and pin 16 of the interface to light
- Providing 5V by pin 15 and pin 16 of the interface to light
the LED through a limiting current resistance which we already
included in our LCM.
- We can light the LED only by inner voltage through a limiting
resistance without any external power supply.
for LED Backlight
Limit resistors must be used for array backlit modules. Refer
to the specific module specification for recommended and/or maximum
backlight ratings. LEDs are arranged in serial pairs and operated
in parallel . The lamp will require 4.2VDC. Brightness can be
set or controlled by selecting the proper limit resistor. Select
a resistor that will drop the remaining voltage at the desired
current. For example, if 200mA produces the desired brightness
and the supply voltage is +5VDC, the limit resistor will drop
0.8VDC (5.0 - 4.2). Therefore, E/I = R = 0.8/0.2 - 4ohms.
Variable brightness can be controlled with a digital potentiometer
or pulse-width modulated circuit.