hello,
I am working on led project,This are some component in project controller ATmega 16 , 25 watt led panel (0.700 mA ,33 volt ) and led panel current controlling circuit to control Brightness of led panel up to 4 level by using ATmega16 PWM port.

i have to doubt on led panel controlling circuit. i am searching option for this i have got one by using power transister, TIP series
http://www.onsemi.com/pub_link/Collateral/TIP120-D.PDF

but i am not sure about this .
any buddy having any other method to control brightness of this 25 watt led panel.
please help...

 

Can you set up your Atmega PWM to output a 100 to 200 Hz PWM ?
If you can then try to vary it's duty cycle.
And after than figure out a way to drive the LED with it.
I would suggest a logic level MOSFET.