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Powering 6.1V laser diode with two CR123A batteries

karolekgaj

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Sep 5, 2022
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Hello, newbie here. I want to drive OSRAM PLT3 520D diode with two CR123A batteries, that means around 6.5V. The diode itself in Datasheet says that operating voltage is typ. 6.1V max. 7.5V. I wanted to make constant current source with lm317, but it needs around 2v input voltage more than voltage needed to drive a load. So, if I will connect this diode straight to the battery, will it burn or work just fine?
I don't want to burn my diode, it's fairly expensive. Thanks in advance!
 





Joined
Oct 18, 2014
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Hello, newbie here. I want to drive OSRAM PLT3 520D diode with two CR123A batteries, that means around 6.5V. The diode itself in Datasheet says that operating voltage is typ. 6.1V max. 7.5V. I wanted to make constant current source with lm317, but it needs around 2v input voltage more than voltage needed to drive a load. So, if I will connect this diode straight to the battery, will it burn or work just fine?
I don't want to burn my diode, it's fairly expensive. Thanks in advance!
you need only lm317 with R = 3.8 ohm! you will have current ~328mA , it is ok for you diode ! good luck bro ;)
your LM317 will run by 2 lithium 3.7V, full charge is 4.2V /each -- > total 8.4V full charge
 

Giannis_TDM

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Apr 27, 2019
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Hello, newbie here. I want to drive OSRAM PLT3 520D diode with two CR123A batteries, that means around 6.5V. The diode itself in Datasheet says that operating voltage is typ. 6.1V max. 7.5V. I wanted to make constant current source with lm317, but it needs around 2v input voltage more than voltage needed to drive a load. So, if I will connect this diode straight to the battery, will it burn or work just fine?
I don't want to burn my diode, it's fairly expensive. Thanks in advance!
The LM317 will have too much voltage drop, it wont cut it, connecting to the battery will kill it, you need a driver, You can either buy one or make one of my open source boost drivers depending on how you want to run it, for a single CR123A use the open source boost as it will automatically raise the voltage to the diode vF at your desired current, you can also choose the buck if you swap out the batteries for 2 lithium 16340s which if I recall correctly are the same size as CR123A batteries. https://sites.google.com/view/giannislasershack/open-source-drivers
Best of luck with your project!
 

karolekgaj

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Sep 5, 2022
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Thanks for your reply! Powering it by cr123a is a must, It will be a handheld laser pointer. I need to design my own pcb, because i also need to add attiny10 microcontroller to get button long press functionality, and it would be the best to have it in one package, because space is very limited. Can you tell me what will be the best way to drive it with 6.5V? Of course, the smaller the solution, the better.
 

WizardG

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Is there a higher voltage version of the AMC7135?
 

gazer101

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Feb 23, 2020
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you can just put multiple amc7135s in series no?
would they be fried if you go over 3V?
 

WizardG

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you can just put multiple amc7135s in series no?
would they be fried if you go over 3V?
6 volts input is the redline for these according to the spec sheet. So even in series, the first part will still see over 6 volts. :-(
 




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