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What's wrong with LED Drivers?

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I've been keeping to the norm and using flexdrives set at 1.5amps, but they get pricey when you have several projects going on.

There is a plethora of LED drivers ranging from 300ma - 750ma - 1,400ma on ebay that can be had for less than $6.

By combining 2 or 3 of these you could achieve a lot of amps as well as have the ability to use voltages from 3-9v.

I currently need a 1.5a driver that can run from 3v – 6v, and was wondering how well these LED drivers would work.

Thanks
 

rhd

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There is *nothing* wrong with LED drivers, except that they don't sound as *awesome*.

At least that's my take. There's a $1.99 linear and a ~$5 boost driver, both from DX (you'll find them here by searching "$1.99" or "NJG-18"), and both are fantastic options that I've used a number of times.

That said, I'd probably put lots of caps on them (input and output), and make sure you get a good handle on their heating characteristics before you assume they can hold up to whatever use you're putting them to. But other than that, there certainly are great LED driver options.

Keep in mind though, people have combed through tons and tons of LED drivers, and the 2 above are the only two that I know of that have been pounded away at, and hold up fairly well (in addition to some of the sandwich shoppe ones that are starting to get reviewed recently - but they're as pricey as FlexDrives)
 

daguin

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The main "overall" challenge with using LED drivers is that LED's are more robust than laser diodes. LED's can withstand spikes that a laser diode cannot.

Peace,
dave
 

rhd

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I've been semi-paranoid when using them - I typically have added a 47uF and 10uF cap to both the input/output.
 

rkcstr

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As Dave said, the LED drivers are not designed to be as "clean" as what we expect for laser drivers. They may produce more voltage spikes at on/off, poor current regulation and more. But, that's not to say they won't work or there may not be one that wouldn't have those problems. However, we just stick to drivers designed for lasers because we know (or expect) they don't have these issues. This has been part of my particular issue with designing a new driver as most current regulating ICs are designed for use with LEDs and won't be the best choice for LDs. Really, there are currently (last time I checked) only two ICs that are well-suited for LD use while being versatile enough for a variety of input/output voltages, and DrLava's drivers use them, haha.
 

rhd

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...Really, there are currently (last time I checked) only two ICs that are well-suited for LD use while being versatile enough for a variety of input/output voltages, and DrLava's drivers use them, haha.
Do you mean specifically boost ICs?

If not, I'm anxious to hear your critique of ICs like the LM1117, 1084, 1085, etc. I've had success with them so far, with good caps on input/output, but I really wouldn't know if I'm doing some sort of non-evident low-level damage to my diodes.

OP:
I think the dynamics of price/benefit may be shifting a bit too, which is perhaps why I'm all gung-ho low-cost drivers, as a new-ish entrant into the hobby relative to some of the more veteran users here.

At this point, you can get a 1500mW 445nm diode for ~$45, and a 12x 405nm diode for ~$35.

Relative to the diode, $23 for a driver is an additional 50 to 70% investment that you wouldn't have to spend if you went with a cheaper alternative. However, when similar diodes were $100+, a $23 driver was probably a lot easier to justify at just ~20% additional cost.

In other words, if I spend $5 on an LED boost driver, add a bunch of caps, I feel pretty safe. If my diode dies, it's $40 down the drain. But that sort of seems like a better approach than tossing an additional $20 in the pot every time I want to play around with something new.

Just my thought process FWIW.
 

LarryDFW

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Blue laser;

The real difficulty with LED drivers is the source.

Chinese vendors change them at will.

What you got yesterday, may not be what you get today.

Just insure that you test them . . .
before using with an expensive laser diode.

LarryDFW
 

rkcstr

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Do you mean specifically boost ICs?

If not, I'm anxious to hear your critique of ICs like the LM1117, 1084, 1085, etc. I've had success with them so far, with good caps on input/output, but I really wouldn't know if I'm doing some sort of non-evident low-level damage to my diodes.
Yeah, sorry, I meant switching ICs for boost/buck/etc. The linear ICs like the LM317, LM1117 etc typically are pretty stable. For my driver, for example, it just needed some capacitors added in various places to suppress noise and oscillation, improve stability, etc.
 

wee40811

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Actually I'm interesting in several flashlight drive board.
I found some of them have very good quality.
??63000???? ??15mm ??3mm??????? - ??HunTer - ???? - ??????????????? - Powered by Discuz!
This driver is from china. I know the designer.
It use 63000 chip ragulate current at 1A.
In put voltage 2.7-5.5V
But the designer tried up to 6V and it still function just fine
Intergrated battery reverse protection.
Five settings can be set by users
2*Li-Fe bettery also work in this driver
the dimention is dia-15mm and high-3mm.
Very compact unit
Will it work in 445 blue LD??
 
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I have been using both dx and sandwich shoppe led drivers and for the most part im pretty satisfied.I figured a schottky diode wired with opossite polarity across the diode pins (smd variant or even thru-hole kind works) + output caps should prevent any damage to the diodes from led drivers. You just gotta find the right value schottky diodes. Like for a 445 blue i use a schottky diode rated at 5.1 volts reverse voltage, so anything over that bypasses the die and goes straight to ground. for blu-ray i use a 7.something diode. It makes sense right? voltage spikes, static, etc that bypassed the capicitor somehow will get caught by the schottky and go safely to ground. I dunno if im totally right but so far even the sensitive 12x blu-rays seems to be fine with a sandwich shoppe boost driver... and @ rhd that one can do 1A and is only 12 bucks. much much less than a flex (1.5A) or microboost (1A)
 




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