Boost Drivers

[bhank]

How exactly do boost drivers work? I've been curious lately and i want to be able to drive a red or BR diode with the power from just 1 18650 or other 3.7v battery. i would also like to have the ability to control output like with the lm317 drivers I just also want to be able to power it to its max with just a lower voltage. if anyone can give any schematics that would help me a bunch.

Thanks

 

[pwNd]

here is some schematics for voltage booster, but i dont find this part LT1327 anywhere to buy.

http://www3.telus.net/chemelec/Projects/Voltage-Boost/LT1372-1.png

 

[lasersbee]

A boost driver is basically an AC step-up voltage circuit..
then the stepped-up AC is filtered into DC that is available
at the output.


Jerry

 

[Krutz]

..think of it as a wall-mount-transformator (powersupply) in reverse. in both the voltage is made into a pulsed voltage, then fed into a coil (or two coils, depends). how the coil(s) are built determines if the output voltage is higher or lower (or the same, if you want) as the input voltage.

much more info, more details:
candlepowerforums: difference between buck, buck boost, and PWM

we dont use PWM ("pulsing") for lasers. but besides that, laserdiodes are very similar to LEDs, just more fragile. ..and cooler, of course ;-)

manuel

 

[dr-ebert]

PWM would be nice for having a dimmable laser...

 

[Krutz]

of course you are right! i totally forgot about the scanner-guys, they use PWM for sure. its just not used for "pointers" here.. ;-)

manuel

 

[bhank]

awesome. thanks guys. I've been out of town for a few days so i just now got a chance to get online haha but i do appreciate your help

 

[diachi]

of course you are right! i totally forgot about the scanner-guys, they use PWM for sure. its just not used for "pointers" here.. ;-)

manuel

Do you mean driving the LD directly with PWM ? Analogue is more suitable, if your scanning you don't want your lasers to be pulsed continually, otherwise you end up with lines.

Boost drivers are switching mode drivers. They use PWM along side a capacitor and an inductor in order to achieve a DC output which has a higher voltage than the DC input (or lower in the case of a buck driver). They are usually >80% efficient if they are well done.