Making a 3V - 6.4V step-up circuit

[diachi]

hello all, i was just wondering today, how to make a 3V - 6.4 V step-up circuit so i can make my ( soon to arrive ) DX labby slightly portable, can anyone help with what components i would need to build it, i know how to solder and stuff so i would have no bother putting it together, thanks for any help

 

[JLSE]

I dont think its an easy road, ive tried myself but just dont have strong enough electronics background to do it. Dr. Lava has very nice boost kits (not sure if he still has any, PM him). I purchased 2 from Jayrob, 1 for red and 1 for BR. I havent had a chance to assemble them yet, but I must say they are well designed and definately worth the money. I took my chances with the 6x build by using such a basic driver, but will be using these new drivers in my next. If you value your diode, I would suggest that you stick with tried and tested. My first attempt for a boost circuit seemed like a good idea, that is until I fried a PS3 diode with it :-[

 

[diachi]

ok, well i think the laser will be ok aslong as i dont push it past 6.42 V, its just the circuit i need, though for now i have a DC adapter that puts out 6.36V so that'll do the job till i get my circuit so i can use batteries, and i PMed BlueFusion to see if he could design me a circuit with a list of components that i could build myself to suit my own size needs etc

Edit : also PMed Dr. Lava

 

[yngndrw]

First of all I'd suggest that you step up past what you need - Say 9V, then regulate the current down to what your laser diode needs.

Stepping up a voltage requires a switched mode converter, which is not simple in any way. It produces a pulsed output which is then filtered. This can however mean that the output voltage can spike up much higher than you'd expect. This type of switched mode converter is called a boost converter.

After stepping up the voltage, you should use a linear regulator to regulate the current for the laser diode. This will produce the most stable supply.

This will not be the most efficient however. If you want efficient, then just use a boost converter with properly tuned filter components. Be warned, to get this setup properly is a pain, hence why I'd suggest that if you have to build your own that you think about the two stage design.

 

[Bionic-Badger]

Depending on your soldering skills, just buy a ready-made one from TI.  You can get the TPS61072 from Mouser.com for about $2.50. I wouldn't be surprised if this is what the Lavadrive2 actually uses. It is TINY, and requires other parts like an inductor, some resistors, and capacitors, but otherwise the only issue is to just solder it together.

If you're not keen on soldering up a tiny chip like that, you can get a Lavadrive2, but they're kind of expensive now since they're in short supply ($50), though normally they're $20.

 

[yngndrw]

$50 for a regulator ?

I'm tempted to make up a load of clones for cheap for you guys.

 

[Bionic-Badger]

Well, it's also because that lavadrive is really tiny, and I think it's assembled too. I wouldn't mind some cheap clones though.

 

[diachi]

Well I dont mind soldering, and my dads pretty good too, so I might give that a try, thanks.


EDIT : Just so this is clear, this isn't to power an LD , its to power another driver that takes 6.2-6.4V and I cant get the correct power any other way than this, plus I want some more experience at soldering and stuff like that .

Thanks again.

 

[Bionic-Badger]

Actually, that regulator I suggested might not be the one you want since you need 6.4V. There are others that do that however. Still, they're not SOT-23 types. Perhaps check this table to see if you find one you can use:

http://focus.ti.com/lit/ml/slvt154/slvt154.pdf

 

[toked323]

Hey get the 61020 I got it from TI (2 of them) as free samples

 

[Bionic-Badger]

Yeah, TI is good about free samples, though after some time they want you to actually buy something.