Let's Make Robots!

fast power transistor

I need advice for a power transistor

Hi all,

Since DanM posted his laser blog I was hooked to the idea of pulse driving laser diodes.

I have created my own pulsing hardware using an ATMega328 to generate a 62.5 ns pulse at 16 Mhz, driving the diode trough an ULN2803 (Toshiba made) which seems to be able to respond well to such short pulses. 

However the ULN2803 is limited in power output so the highest current I could sink is about 700mA (I know the ULN2803 is limited to 500mA yes) by parralelling outputs. At this level the ULN2803 is way over its limits and starts overheating.