Leds Dimming or Lower voltage?

Hi,
I came across a circuit today and i saw some dimming leds sequences.
Its like it fades off rather than turns off straight away..

When i take a closer look, it uses a PIC16F628A.
The circuit is relatively simple it uses MOSFETs.

Is there a way to write the program as such??
Variable output voltage??

Thx in advance..

The PIC just uses PWM to dim the LEDs. It just varies the duty cycle of a squarewave to change the LED brightness. The square wave is of a high enough freqency that your eyes don't see the flicker.

Thx for the explaination..
Btw do u have some code sample that i can refer to?
and wats PWM?

vinvin said:

and wats PWM?

Click to expand...

If you ask google I'm sure you'd find out, but it's Pulse Width Modulation.