LM1085 DIY Driver

[Ghostchrome]

I *think* it's a fundamental flaw in the concept of using a PCB-mounted TO-252 version of the IC. The bottom side of the IC, with the thermal pad, is heatsinked to the PCB itself. You rely on arctic silvering the WRONG side of the IC (the epoxy/plastic top) to the pill/heatsink/host.

I just don't thinke TO-252 ICs have enough:
- Surface area to dissipate the heat to the air
- Volume to absorb the heat in the first place

However, I'm stumped because I feel like if this was the case, we'd be hearing similar complaints about lots of the drivers out there. The Jib 1.8, the Mohgasm 1.8, etc. And we don't - or at least I've never heard anything negative about those drivers.

I've never (until now) wanted to use a TO-252 IC. I've always suffered with the larger packages, as a trade off for knowing they could handle themselves. But obviously people use 252, and *must* be having some luck with it, otherwise I wouldn't see it used so much.

Well, mine may or may not be a moh 1.8A

I just figured that mine was maybe not heatsinked very well or that I got one with an IC that wasn't really performing up to par since I've never heard of anyone having problems with them either. Heck, I figured the diode would have trouble before the driver. Anyway yeah, you could be on to something there about the design of that particular IC package. Maybe I'll try totally covering the driver with thermal epoxy, maybe squish a piece of metal or two on it and see if that helps. heh

 

[m3vuv]

Well, mine may or may not be a moh 1.8A

I just figured that mine was maybe not heatsinked very well or that I got one with an IC that wasn't really performing up to par since I've never heard of anyone having problems with them either. Heck, I figured the diode would have trouble before the driver. Anyway yeah, you could be on to something there about the design of that particular IC package. Maybe I'll try totally covering the driver with thermal epoxy, maybe squish a piece of metal or two on it and see if that helps. heh

just talking about regulators did she some testing today,some time ago i was running a 450nm m-140 strait from 2 18650 cells in series via a lm7805 reg,it worked fine,they are rated at 1500ma top whack,any way i decided to build another the same,this time i measured the current from the 7805 basicaly shorting the output via my fluke,it was showing out 2 amps,just goes to show how to show how they can vary from part to part,good jom i checked!! m3vuv

 

[lasersbee]

You are aware that this Thread is 7 years old....
That is called Necroposting and is not good
Forum Etiquette.

You could have easily opened a new Thread.

Jerry