LED driver as laser diode driver

Please correct me if I'm wrong but the source of light for a LASER is a diode. As long as the electrical characteristics are the same could I use this LED driver for my laser? NCL30160 datasheet

It lists a maximum current of 1.5A and can be configured for any load, has enable and extremely high frequency switching capable.
I'm sure this has been done before but my search yielded no results. Any tried this or know of the downsides?
Thanks.

Not sure about that one but the amc7135 is a led driver thats been used for the mits 500 before

As long as it's current controlled, and the voltage/current ranges match your diode, yes.

I'd even say that most cheaper laser driver boards use chipsets originally intended for LEDs.

I don't know how much experience you have with electronics like this, so keep in mind that these are not like what you see in tutorials where you can just solder a little board to the diode. They're ICs meant to be a part of a driver circuit. They'll need external components besides the IC to maintain the current.

Hi Riv,
Is that true for the amc7135 also?

VirtueViolater said:

Hi Riv,
Is that true for the amc7135 also?

Click to expand...

The amc7135 is a fixed current driver IC it 350mA, so you won't need external resistors or caps as part of the current regulation, but you should have some capacitors for stabilization. Just check a datasheet for an example.

AMC7135 is a linear, low drop, constant current regulator intended for driving leds from batteries with only a small voltage above what they require. It can be used for lasers as well, also for driving pump diodes from 2 NiMH cells etc.

However, the chip in this topic is something else entirely: It's a buck switchmode converter with current limitation.

This can still work fine as is proven by a load of laser drivers operating under the same principle on the market, but you have to be a bit careful.

One big difference between lasers and leds is how they handle short situations of overcurrent. Most leds fail from overcurrent due to thermal reasons, where laser diodes have problems with optical breakdown of their facets.

This means a driver can briefly send out a jolt of current on, for example, switch on, into a LED and be fine, but it would fry a laser diode if that brief period was only a millisecond.

The only way to be certain is to hook the driver up to a dummy load, and watch current on a scope during power-on, adjustment and power-off. If you see no overshoots it should be fine for laser use.

You can probably see it on an analog scope, but it works best if you have a digital scope with storage that can operate in single-shot mode so you can easily examine the power-on and power-off behaviour.

Great info guys,
Thanks!

I think it will work just fine as a laser diode driver. All laser diode drivers (and led drivers) are essentially voltage regulators. They simply regulate to voltage over a shunt resistor and, because V=IR, regulate the current.

Looking over the datasheet its seems fine, but I would add capacitors to the output to clean it up a little bit since laser diodes are a bit more sensitive than leds. You can see the funky output in on of the graphs on the datasheet. Only down side is it doesn't really handle much current.

THANK YOU!!!! Thanks for such great responses. I'll order one and some test components. It seems like it would have way more functionality than a similar lm317 circuit. I'll hook it up to the scope and do a comparison of overshoot when switching with this vs the lm317. Will be a while but I'll provide a detailed report with my findings.

Sounds like a good idea!

The main disadvantage of the lm317 circuit is it's enormous voltage drop requirement - theoretically 4.25 volts to keep wihtin the specifications of the chip, although you can get away with less for most real world chips.

kaminsknator said:

THANK YOU!!!! Thanks for such great responses. I'll order one and some test components. It seems like it would have way more functionality than a similar lm317 circuit. I'll hook it up to the scope and do a comparison of overshoot when switching with this vs the lm317. Will be a while but I'll provide a detailed report with my findings.

Click to expand...

Do you have experience with circuit design? Because you are probably gonna need to design a pcb to get that working. If you want I could make a quick board file in eagle.

And I would order extras just in case you blow one! Its happened to me plenty of times.

If you come out with a working circuit please post it in my custom driver thread!

Ok thanks for your help, I will keep everyone posted on the design. It's a number of months out from completion just bought a house and time is limited currently.

Take your time for it

Surely you will damage some components when prototyping things, this is fairly normal and happens to everyone i think.

Just try your designs on dummy loads to avoid blowing up expensive laser diodes, accidently smoking out the odd transisor or opamp is just part of 'the process' sometimes