3.3V digital PWM to 5W analog signal
If you just want it to work with zero effort and don't care about spending extra $$, there are &quot;PWM-to-voltage&quot; chips that do the conversion at maximum speed for you. For example LTC2644. If you take that route, it's quite easy, you just need to pick the clock speed.
If the laser spends 1ms on each pixel, you would need the conversion-to-analog to settle in some fraction of 1ms, to produce an acceptable image. 100 us would probably be the bare minimum, 10us would probably be pretty good. But be prepared for surprises -- the eyes are quite sensitive.
A ~200kHz clock speed should be a good place to start -- but only if you're using the method of the LTC chip above.
Now if you want to save some money, you'd increase the clock quite a bit to make room for a cheaper filter. Design a higher order filter to get the &quot;90% rise time&quot; under 10us, or whatever number you picked as &quot;good enough&quot;. Then set the clock high enough that the filter attenuates it to a level that wouldn't be visible. Otherwise you can have some moire patterns in your laser printed image from aliasing effects.