lasorbs... should they have protected my diodes?

[shrad]

well Andy you may also continue here if desired, as I think everything was said about my misadventure

your design is really clever and useful, so there is big profit from your "spam"

[drlava]

Many people have had great success with - regulated drivers and cathode common diodes, but it does require an extra bit of paying attention to make sure things don't get shorted. - regulated drivers are best with common anode diodes (IR) and isolated diodes like blu ray. However for DIY red, because of occasions like this, there continues to be a request for a common anode driver.

Andreas posted a nice one above and I've been working on one as well. Let me just rant - it's frustrating trying to spec and build a high speed analog driver when the electronics industry is constantly obsoleting critical parts with no replacement! The FET you found is certainly still a jem, not many others that are still available will work well in this application. Unfortunately (not your fault) it delivers its heat to the PCB instead of a heatsink. That's another problem.. the industry obsoleting 'old packages' like to-220 in favor of SMT or tabless to-220 look-alikes (dpak-3). In your case with low power it's not a problem at all, but in other designs pulling 20W of heat away from a smt d-pak is a lot harder than from a to-220!
end rant.

[andythemechanic]

Andreas posted a nice one above and I've been working on one as well. Let me just rant - it's frustrating trying to spec and build a high speed analog driver when the electronics industry is constantly obsoleting critical parts with no replacement! The FET you found is certainly still a jem, not many others that are still available will work well in this application. Unfortunately (not your fault) it delivers its heat to the PCB instead of a heatsink. That's another problem.. the industry obsoleting 'old packages' like to-220 in favor of SMT or tabless to-220 look-alikes (dpak-3). In your case with low power it's not a problem at all, but in other designs pulling 20W of heat away from a smt d-pak is a lot harder than from a to-220!
end rant.

No Problem, but there are still TO-220 options for P-Channel Mosfets. In my former design (http://www.photonlexicon.com/forums/...9912#post99912) I used the irlib9343 and that also worked well. I tested it up to 5A with a good heatsink. I switched to a SMD device now because I had the feeling there are not many applications where a high side driver with more than 1A current is needed. The high power C-mount for example I think they are case positive. Up to 1W dissipation is no problem for my current design. If this is not enough it's quite easy to just exchange the Mosfet in the layout.

Andreas