most dimmable buckpucks can be pwm'd with out a filter.At least mine do, 3021-d-e-700ma. the problem i have is i want to use a 12v rf pwm dimmer, when the pucks need 0-5v, backwards mind you (5v full off, 0v full on). that means up is down and down is up on the pwm dimmer rf remote.
I had a rough build working using a 12v dimmer to trim the voltage with a 1k pot on the output to kick out 0-5v (well not exactly, as its pwm not analog 0-5), but powering the dimmer from a sepic (to keep a constant voltage when the led's drop the voltage, since they are both wired to the same 1.25a 12v ac/d transformer), seems kind of sketchy as its putting alot of current into that control pin potentially, compared to the measley 40ma it needs. It works, but both the driver and pwm dimmer must have sepics to prevent voltage drops that screw with the driver and dimmer. Ideally schottkys as well, if you need more current and have to wire up parallel sepics.
The cool thing about those sepics though, is you can power them off pretty much any dc source, batteries, ac/dc transformers, hell even solar panels.
I think the next thing im going to try w/ this idea, is taking the 5v ref pin from the buckpuck, take the groung from the main sepic, and use one of these 3.5-10v > 12v boost converters, to try and run the dimmer off that. Then a pot to trim the voltage, or alternatiely, wire up some mosfets to switch the 5v+ ref pin, and the control wire for the buckpuck open closed via pwm to dim the driver.
If either of those last two ideas work, then its as simple as analog write (well pwm, but it still works)to digital pwm output on my arduino. Thn i can use 1 rf dimmer for multiple high power smd led's using an arduino to write several pwm outputs from that analog input of 0-5v from the pwm dimmer. Or just buy more dimmers, as they're under $10 ea on ebay.
BTW, can anyone recommend a mosfet that is fully on @ 12v? i' like to just use something like that ont the output of the 12v pwm dimmer, to pwm switch the 5v 40ma 5v out on the buckpuck. I have bunch of irf46zn's laying around, but from what i read on its data sheet, its gate voltage is fully on at 4v. I need something that will be fully on at 12v.