Micro Boost and LOC 815 diode

Hello, I am in the process of building a portable laser using a long open can LPC-815 red laser diode. I purchased the host from Ehgemus and it will be powered by a single CR123 3-3.2 volt battery.

Since Dr. Lava is out of the flex drives, I instead ordered a micro boost driver. From what I understand, the micro boost drivers are primarily used for +4 volt Blu-Ray diodes and not 2.5 volt LOC diodes. I went through all the documention about the driver and I plan on setting the current to just under 400mA but I don't see anywhere how I can set the output voltage. By setting it at 400mA current, I do not want to over boost the voltage to where I may blow the diode.

(Vout * Iout) / Vin < 1.2 =OR= (X * 0.4amps) / 3volts < 1.2

So what would be the driver output voltage on a freshly charged 3 volt CR123 battery?

(9 * 0.4) / 3 = 1.2

9 Volts?!? My math must be wrong, please help

EDIT: I canceled my order for the boost drive since the host is grounded to the case pin of the diode and will short out the boost driver. Dr. Lava sent me an email saying the flex drivers will be available the first week of October.

No, you're right. Microboost cannot be used on red builds.

The MicroBoost is a boost only driver so it cannot drop the output voltage, (or buck the voltage), down to ~2.5V LOC. From info gleaned in the 445 threads then the driver can only cope with driving a diode 0.35V below the battery voltage. This mean dropping some volts somewhere. I posted a similar question a while back but don't think an answer was forthcoming. I asked where I could drop the volts... Use a 1N4001 diode before the driver input or between driver and LD? I get the feeling putting it between driver and LD would throw out the current through the LD but I am not sure. Putting it before the driver input may work but I don't know if there would be any side-effects.

The driver, under the circumstances within it's specs, will output the required voltage by whatever you are driving. You do not need to, 'set', voltage output, just work within the stated ranges.

M

A diode can be added to drop voltage on a linear driver. I'm not sure how it would effect a microboost though.

Funny, I was told to get the boost driver with my combination of red diode + single 3 volt battery.

How do people normally power these diodes using one CR123 battery?

paulzimm said:

Funny, I was told to get the boost driver with my combination of red diode + single 3 volt battery.

How do people normally power these diodes using one CR123 battery?

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With a FlexDrive or a DIY driver like the LM317 based DDL.

What about the Groove V2 driver?
http://hacylon.case.edu/ebay/laser_diode/Groove_2.php

Thanks again for ALL your help - this forum rocks!

Groove requires vout+1.2. This puts the requirement for a red around 6.6v minimum. This would still require 2 cr123 batteries same as a rckstr.

jib77 said:

With a FlexDrive or a DIY driver like the LM317 based DDL.

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Even a DIY driver with LM317 requires around 7 volts:
Laser driver - It can be done

So my ONLY option is to wait for the Micro Flex to come back in stock?

What about one of the O-like drivers? I see tons of single 3 volt battery red LD hosts on this forum so there must be another option:
http://www.*****************.com/shop/4-laser-diode-drivers

PS - I just now got a message after I canceled my Micro Boost order from Dr. Lava himself:
"Hello, note that the FlexDrive is temporarily out of stock but will be here in early Oct. Regards, Andrew"

check this new thread in the driver section: http://laserpointerforums.com/f67/d...m-diodes-up-200ma-cheap-unfinished-55638.html. Rafa is powering a red diode with a single Li-Ion and his linear driver.

If you want a switching regulator you might also look at doing one based on the LTC3490 (recommended by erdabyz). Max input is 3.2V and you get a fixed 350mA current, very low part count(IC, input and output caps, and inductor).

LTC3490 Datasheet

The reason the microboost cannot be used other than the obvious voltage is that the driver is a floating - current regulater... The reds use the case ground as their ground.

The 405nm 445nm or ultra violets have a isolated ground pin as well as anoid pin.
so by hooking the driver up to a red is essentially bypassing the driver.

jander6442 said:

The 405nm 445nm or ultra violets have a isolated ground pin as well as anoid pin. so by hooking the boost driver up to a red is essentially bypassing the driver.

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Thanks Jander, you just saved my diodes life! I guess I am going to "tough it out" and wait for the flex drive if I want to use a single 3.2 volt CR123 battery with this diode...

I'm just regurgitating what I've picked up from Jayrob. So I'll pass the thank you on

jib77 said:

If you want a switching regulator you might also look at doing one based on the LTC3490 (recommended by erdabyz). Max input is 3.2V and you get a fixed 350mA current, very low part count(IC, input and output caps, and inductor).

LTC3490 Datasheet

Click to expand...

If you are fine with a LDO drain linear regulator, I've had a good run with the AMC7135. No external parts required, but an output cap might be a good addition.

paulzimm said:

(Vout * Iout) / Vin < 1.2 =OR= (X * 0.4amps) / 3volts < 1.2

So what would be the driver output voltage on a freshly charged 3 volt CR123 battery?

(9 * 0.4) / 3 = 1.2

9 Volts?!? My math must be wrong, please help

Click to expand...

From what I understand after browsing around here:

This formula shows your input/output conversion and shows that when you plug in your known Vin and Vout (forward voltage of the diode can be used for Vout i assume) if the outcome of the left side of the equation is less than 1.2 than the driver will work (combination of Vin and Vout is suitable). This formula can not be used to calculate your Vout, Vout will be your diode's forward voltage at a current you are driving.

Also look at this: http://laserpointerforums.com/f64/l...lavadrive2-fits-pens-22502-56.html#post784259 and the next post.

As I have said I have driven my LPC-815 at 450mA with microboost. When measured the Vf across the diode was 3V (battery's voltage since it only boosts or keeps V the same as batterie's) which is according to the lpc-815 datasheet a maximum operating voltage for this diode. It seems that If you can make a build that will isolate the heatsink or the module with diode from the case (case is often used as ground/negative) and find a way to feed 3v or less into the driver (1n4001 diodes in series between the powersource and the driver for example) you will be fine.