Connecting 200 LEDs divided into 3 groups with pwm

Other Hardware LEDs and Multiplexing
2

You probably want to drive the LEDs with a higher voltage (say: 12V to 50V) so you can put a bunch of LEDs in series. Try this online calculator:

http://led.linear1.org/led.wiz/

Then you can use an NPN transistor that can handle the voltage and current to switch the array on and off via a PWM pin.