• State
  • Locked Locked
  • Replies 2 replies
  • Subscribers 62 subscribers
  • Views 1423 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

Drive a GLCD backlight from PIC 3.3V GP I/O

COULON Laurent
Prodigy 230 points

Hello

I'm looking for a part that will let me drive the cathode of GLCD.

My project is using a PIC 18F2620, 3.3V powered. With a PIC GPIO i need to drive the GLCD backlight cathode in order to switch On / Off the backlight.

GLCD anode is tied to +5V.

 

Actually, what part shoud i consider to drive a led powered from +5V voltage with a GPIO delivering 0 - 3.3V ?

Many thanks for your help,

  • 0
    Prodigy 10 points

    I would use an NPN (or NMOS) controlled by the GPIO. 10-47K in series if using an NPN. Then if you know the supply is always 5V, you can find a suitable resistor to place in series with the LED to set the current. 5V-LED-Resistor-NPN-GND, GPIO-10K-NPN-GND. 

  • 0 in reply to Jacob Lerenius
    Prodigy 230 points

    Thanks, but the GLCD backlight can only be driven by anode pin ( cathode is internaly tied to GND )

    Would that schematic be correct to do it ?

    If GPIO delivers 3.3V when active, would it be enough to get Q1 passing the current into the backlight led ?