LCD Backlight Analysis:
Current/Power | blue LCD | transflective (sunlight readable) LCD |
backlight on | 82.4mA 644mW | 251.6mA 1950.4mW |
backlight off | 53.2mA 416.2mW | 53.2mA 416.2mW |
The LCD backlight turns out to be a real power hogger. 1950 milliWatts? Whoa!! Maybe I should read the datasheet more often..
240-280mA! I thought I had a short circuit, but apparently, this LCD uses that much current for the backlight. From now on, the backlight will be off in my circuit (cut pin 15 to the display), but I added a switch, just in case.
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NO problem Tobias
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Hi David, I am using Sam Knight's PWM library
https://code.google.com/archive/p/arduino-pwm-frequency-library/downloads
Just uploaded it to my repository, just in case
https://github.com/atmelino/Arduino/tree/master/libraries/PWM
very easy to use:
pwmWrite(PWM_OUT, pulseWidth);
Fortunately, the transflective LCD is easy to read in sunlight without a backlight. I added a button to briefly turn the backlight on if necessary, but I figure most of the time you don't need a backlight at all. Thanks for the suggestion though.
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Hey Tobias, man, that's is a big energy hog. Since you are using an Arduino, how are you controlling the PWM duty cycle? Usually you can design a dimmer for the LCD backlight and have the switching frequency set to about 200 Hz and maybe control the duty cycle at 25 to 50 % duty cycle to shave some of that current down.
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