AMC7135 needs heatsinking ?

[Blord]

Is it possible to use these driver to provide 1.4A current to 445nm diodes ?
And does it need heatsinking when it is possible to use ? I mean do they get hot if they are providing 1.4A ?

DealExtreme: $33.94 AMC7135 1400mA Regulated Circuit Board for DIY Flashlights 20-Pack

 

[JLSE]

They get very hot if used with 2 x 3.6v Lith..

The ones I have tried work, but need to be cooled
or they go into protection mode and flicker.

Aside from the 3 months ive been waiting for my order
of the 7135s, ive given up on using these boards.. :banghead:

 

[Gryphon]

Wouldn't 2 lithiums be above its input voltage?

 

[JLSE]

Wouldn't 2 lithiums be above its input voltage?

Yes it is, but there are ways around it. There is a zener
on the boards as is. You can add another to drop the voltage
a little further..

As long as you heatsink well, they can take it no problem.
It just adds heat to the laser in general...

If you mount the 7135 PCB to the back of the heatsink
it will operate stable. If the heatsinking is sub par.
the laser will pulse each time 1 of the 4 7135's drop
out from heat.

In one laser I made, it seemed only one
of the 7135 chips on the board was dropping out for
a half a second or so.. The output would dim out
a few hundred mW and then come back up..

They each go into protection mode out of sync, which
results in random flickering...

 

[Benm]

These devices may require heatsinking, depending on the voltage drop over them. Remember they are only rated for 6.0 volt input, so anything beyond that cannot be guaranteed to work at all.

Still, if you would use one from a 6 volt source to feed a 3 volt red laser diode, the dissipation in the device would be 1 watt, and it would need cooling. The normal procedure for SMT devices like these is to make a large copper area connect to the tab, but you can also find other solutions: Its quite feasible to attach a small heatsink to the plastic of the device using thermally conductive adhesive.

The boards as pictured lack any heatsinking, and must be in thermal contact with a flashlight host to work reliably. The chips themselves do have overheat protection, but that will result in them cutting the current to your laser diode when overheating. If you use several of them in paralel, one or more may overheat at any give time, and you lose 350 mA of current drive, resulting in irradic behaviour - fluctuations in output power, flickering on and off etc.

 

[JLSE]

Its unfortunate they dont make these in + side regulators..

The 7135's are reliable, but an awkward build when using
case - LD's (most 650nm LD's @ 5.6mm)

You either have to insulate common red LD's, or incorporate the
7135 between the switch and body..

 

[Benm]

They arent convenient in that regard indeed... and i don't know of any positive side equivalent either.

These things are obviously LED drivers, where the entire die is usually isolated from its base, but they can be used as replacement drivers for DPSS greens - many of the lower powered pointers operate at 350 mA or so.

 

[Blord]

They are usefull in a lab laser. The driver can easily isolated from the diode/heatsink.
And the fixed 350mA current is pretty handy :

one AMC7135 for a LOC red diode,
two AMC7135 for a 12x BR diode,
four AMC7135 for the 445nm diode.

 

[ndrew2505]

i used 1 of those with a 6v wall wart to make a labby. they get warm but not extrememly hot unless your using too much voltage. i used some small vga/ram heatsinks with some thermal epoxy.

 

[JLSE]

They arent convenient in that regard indeed... and i don't know of any positive side equivalent either.

These things are obviously LED drivers, where the entire die is usually isolated from its base, but they can be used as replacement drivers for DPSS greens - many of the lower powered pointers operate at 350 mA or so.

I bought a cut reel of the IC's from a guy in China.
He also could not find + side regulators in the same
family.

I think the closest was a similar LDO + side, but a
voltage regulator.. Also non adjustable.

 

[mpmsfilho]

Hi, is possible to power my 445nm diode with the AMC7135? (using a 4,5v battery or I need more voltage?)

Thanks

 

[Blord]

Read this thread. It will answer all your questions. You should use the search engine better.

http://laserpointerforums.com/f65/idea-driver-host-51446.html