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Topic: HD44780 LCD Backlight control with PWM (Read 12 times) previous topic - next topic

GaryP

The only law for me; Ohms Law: U=R*I       P=U*I
Note to self: "Damn! Why don't you just fix it!!!"

pixelk

a pulldown resistor so that the mosfet doesn't get high when it shouldn't. Is it wrong ? Should I remove it completely ? I had doubts about it.

GaryP

Well, examine  it a little, and tell me what it does in your circuit.

Kari
The only law for me; Ohms Law: U=R*I       P=U*I
Note to self: "Damn! Why don't you just fix it!!!"

mowcius

I have to admit I'm not really up on FETs but I think that link I posted is confusing :P

In your case you don't want the 10Kohm resistor - it was only there on the linked one due to how it was wired with the external supply.

So LED- to D, S to Ground and G to D3

I'd personally put the 150ohm resistor between S and Ground but that's just personal preference

pixelk

#19
Mar 20, 2011, 11:27 am Last Edit: Mar 20, 2011, 11:31 am by pixelk Reason: 1
[font=Verdana]Kari [/font][/b][/size]: looks like the 10k sucked all the juice from the lcd in my previous schematic.

[font=Verdana]mowcius [/font][/b][/size]: It seems right now, thank you.

Here is the final (more simple) design :



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