Please suggest any good laser diode driver ICs..

[arbj2]

Can anyone suggest a simple laser diode driver IC, that can drive a NPN/PNP laser diode ??

Something like this would be suitable...https://www.ichaus.de/product/iC-WK%20iC-WKL

I looked at some Maxim products but they are mostly communication based ones, all I need is a simple one for pointing application.
thanks
a

 

[keith1200rs]

For a laser pointer a two transistor circuit is all you need - no complicated ICs. Have a look at https://www.repairfaq.org/sam/laserdps.htm - there are some useful circuits (not very well drawn) but make sure you read the description in choosing one - some are not very good!

Keith

 

[arbj2]

but is the circuit stable enough at elevated temperatures ?? say 40 degC ??

 

[keith1200rs]

The 2 transistor circuits are fine for laser pointers. They often use Vbe as a voltage reference so the laser power will vary with temperature but that shouldn't be an issue. Monitor leakage will increase with temperature anyway.

Keith

 

[arbj2]

The LM317 circuit looks OK, as it is also constant current, and hence longer diode life. I could limit the voltage to 5 V using a DC-DC converter. In such a case a minimum input voltage of 7 V would be needed to generate 5V DC.

Is it possible to operate the circuit at 3 V DC instead of 5 VDC, the lasing voltage for my diode is 2.3 V, I could not find anything lower..

Is it risky to run the diode just like a LED, without using the PD for feedback ???

 

[keith1200rs]

As I said, you must be careful with the circuits there as it is a review of circuits around - good and bad. If a laser has a built in monitor diode then you must use it and choose your circuit accordingly.

Keith

 

[jayanth.devarayanadurga]

Try this links https://www.teamwavelength.com/products/

 

[keith1200rs]

Just to repeat, do NOT use LM317 based constant current drive for a laser with built in monitor diode.

Keith

 

[arbj2]

thanks keith1200rs for the help..your information has been very helpful indeed..

I checked out some the driver ICs listed in the link you posted...most products are meant for communication purposes (but I have bookmarked them), ichaus has a very good driver chip, but this is a bit pricey....

Finally I tried out my version of a driver, I used a PIC 10F222 to generate a PWM output, drives the LD through a NPN transistor. The current through the LD is limited using a resistance on the emitter..

Do you think the pulses would damage the laser diode. ?? Although there is a 0.1mfd and a 1N4148 diode in parallel to the LD.

thanks
a

 

[keith1200rs]

What is the laser part number?

Keith

 

[arbj2]

its a QSI make laser diode, NPN type, part no: QL65D7SA

 

[keith1200rs]

In which case you will most likely blow it up. It has a high slope efficiency once you get past the 'knee' of the characteristics. The position of the knee is variable and temperature dependant. There is also a not on the datasheet that it must be operated with APC - automatic power control.

Keith

 

[arbj2]

the current through the LD is well within the specified range.

In this case the diode functions like a LED...maybe I could use the PD current as a feedback to control the LD current....

 

[keith1200rs]

It is not the current you need to worry about - it is the laser optical power. If you exceed the absolute maximum optical power you will destroy it. Without a power control circuit you cannot be certain that you won't exceed the maximum optical power.

Keith

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Also, if you don't drive it to the point where it lases the output will be very low.