| ??? 07/04/05 14:20 Read: times |
#96518 - PWM - LCD backlight |
Hey forum
Messing around with a small 8051 aplication, I got an idea. I need 5V and a few mA's for my 8051, MAX232 and the controller on the LCD. A 7805 would come in handy. I need a lot more power for the LED backlight on my LCD. About 500 mA for a 4x40 type. I could use a switched PSU, but since my micro got a PWM output, how about making a currentcontroller around a simple op amp and a transistor - a IRFD 110 f.x. Then pulse the op amps positive input with the PWM. By selecting a proper feedback/currentlimiting resistor i prevent current exeding whatever the dispaly can handle. Is this workable, or have I missed something? How do you drive your LED backlight? Happy 4th of July! ha' en god dag Per Guldmann |
| Topic | Author | Date |
| PWM - LCD backlight | 01/01/70 00:00 | |
| One Approach! | 01/01/70 00:00 | |
| Why not. | 01/01/70 00:00 | |
| Not an entirely good idea | 01/01/70 00:00 | |
| But | 01/01/70 00:00 | |
| But but | 01/01/70 00:00 | |
| hmm | 01/01/70 00:00 | |
| Apologies | 01/01/70 00:00 | |
| Buck, actually | 01/01/70 00:00 | |
| Bugger it. | 01/01/70 00:00 | |
| Bugger it | 01/01/70 00:00 | |
| Capacitor? | 01/01/70 00:00 | |
| biology | 01/01/70 00:00 | |
| Per | 01/01/70 00:00 | |
| development | 01/01/70 00:00 | |
| I got that working nicely.... | 01/01/70 00:00 | |
| Well Done | 01/01/70 00:00 | |
| what I do | 01/01/70 00:00 | |
final cut | 01/01/70 00:00 |