LCD display backlight voltage

Discussion in 'The Projects Forum' started by eminthepooh, Nov 8, 2012.

  1. eminthepooh

    Thread Starter New Member

    Aug 26, 2012
    Hello, I'm designing a system to be mass produced which has this charecter LCD (common HD44780 controller). As stated in some datasheets the LCD backlight voltage drop is minimum 4.2V maximum 4.8V. I'm controlling its operation with a mosfet and resistor as seen in the picture.

    I'm wondering if there is an easy/rule of thumb way to design without a pot (currently using pot set at ~4ohms) so that my circuit with work every time regardless of the backlight voltage drop. I've considered going to a 12V power supply to have a greater range in control. Any suggestions?

    Thank you,
  2. ScottWang


    Aug 23, 2012
    The better way is fixed the voltage of backlight of LCD.

    If you need to adjust the voltage of backlight, you could use the DIP Switch to choose the resistors you want, the DIP Switches has many kinds of pins, as 2,4,6,8,10,12 pins, DIP Switch.
  3. tubeguy

    Well-Known Member

    Nov 3, 2012
    Could you post a link to a datasheet for this device?