FREE DIY open source BOOST driver!!! Tested & working!!

[chefla]

One question I've had about inductors, in a buck configuration does the inductor need to be able to handle the max switch current or the max output current?

In a buck configuration your inductor current is your switch current, is your load current. All of that is in series when the switch is on.
In cases where you use caps on the output there will be some additional current going to re-charge the caps during cycles. But there only are a few cases where you have to take that additional cap current into account. Most inductors anyways have a rated inductance with a +/-20% tolerance window, so unless you pick one right at the lower limit you should be fine.

 

[Jubathoph]

Guys

Forgive me if this is a dumb question. R1 and R2 are your "set resistors" which are in series with the LD between L- and ground. The IC is maintainin a feedback voltage of 190mV through the resistors by regulating current through the LD. That means that the L- is voltage is at +190mv, Right?? How is this used with a case negative diode and a grounded host? If the LD- is bonded to the host and the host is at Ground the set resistor would be bypassed..

Let me know if my question is unclear. Thanks

 

[foulmist]

Guys

Forgive me if this is a dumb question. R1 and R2 are your "set resistors" which are in series with the LD between L- and ground. The IC is maintainin a feedback voltage of 190mV through the resistors by regulating current through the LD. That means that the L- is voltage is at +190mv, Right?? How is this used with a case negative diode and a grounded host? If the LD- is bonded to the host and the host is at Ground the set resistor would be bypassed..

Let me know if my question is unclear. Thanks

you should isolate the laser diode case (LD-) in this situation from the host (GND) :beer:

 

[tsteele93]

you should isolate the laser diode case (LD-) in this situation from the host (GND) :beer:

How does that affect heat sinking? How do you isolate the case electrically while still maintaining a thermal connection?

 

[Wolfman29]

It generally just makes it harder to heatsink, unfortunately.

 

[Blord]

How does that affect heat sinking? How do you isolate the case electrically while still maintaining a thermal connection?

You could anodizing the host or the sink or both. That is the reason I like the C6 host. Electrically isolated while thermally connected.

 

[rhd]

Can I ask a practical question?

What case-negative diode would you be using this driver with? I'm not sure I can think of one that you would use this driver with off hand.

 

[LuxorLasers147]

How does that affect heat sinking? How do you isolate the case electrically while still maintaining a thermal connection?

You could anodizing the host or the sink or both. That is the reason I like the C6 host. Electrically isolated while thermally connected.

Thermal tape. If i remember right, lazeerer used it in his 2W build, around the module. But i guess you can wrap it around the sink, if your dealing with a press fit. "no problem" he said :beer:

 

[rhd]

Thermal tape. If i remember right, lazeerer used it in his 2W build, around the module. But i guess you can wrap it around the sink, if your dealing with a press fit. "no problem" he said :beer:

It's probably "Kapton Tape" that we're talking about.

However, my question from this post still stands:
http://laserpointerforums.com/f67/f...iver-tested-working-71433-11.html#post1040529

 

[Jubathoph]

Yeah my queston was geared towards case neg diodes most of which don't need boost. The reason I asked is this is the same configuration my buck IC uses which is powering case negative diodes. In that case I will gave to isolate the diodes from the host, no problem. I was just wondering if I had interpreted the circuit correctly which it looks like I did. Didnt mean to derail the thread :beer:

 

[LuxorLasers147]

It's probably "Kapton Tape" that we're talking about.

However, my question from this post still stands:
http://laserpointerforums.com/f67/f...iver-tested-working-71433-11.html#post1040529

Dont really know, I think i read "thermal".

You know may opinion about this. LPCs need too much voltage to work at high currents with a linear driver out of 1cell. So i dont see anything wrong in using a 5$ driver, and it works haha. The only problem is the GND.
Remember the ST drive (ST i think)? it´s almost the only linear that can do it with one cell, but its 10$+

 

[rhd]

You know may opinion about this. LPCs need too much voltage to work at high currents with a linear driver out of 1cell. So i dont see anything wrong in using a 5$ driver, and it works haha. The only problem is the GND.
Remember the ST drive (ST i think)? it´s almost the only linear that can do it with one cell, but its 10$+

I see another problem.

This isn't a buck driver

You can't run a diode that has a Vf of less than 3V, from a cell that will provide a voltage of up to 4.2V, with a boost driver.

For that matter, the ST Drive actually won't always work either, because technically it requires a VIN of 4.5V for that IC to operate. It sometimes works on less than that. But in practice, I'm growing to hate those ICs.

 

[Hiemal]

RHD, PHR-805T's are case negative if I remember right.

 

[foulmist]

I see another problem.

This isn't a buck driver

You can't run a diode that has a Vf of less than 3V, from a cell that will provide a voltage of up to 4.2V, with a boost driver.

For that matter, the ST Drive actually won't always work either, because technically it requires a VIN of 4.5V for that IC to operate. It sometimes works on less than that. But in practice, I'm growing to hate those ICs.

someone may still try to run it with 2 AA or 3AA alkaline/Ni-Mh batteries or even 1 AA
not me though
:beer:

 

[LuxorLasers147]

I see another problem.

This isn't a buck driver

You can't run a diode that has a Vf of less than 3V, from a cell that will provide a voltage of up to 4.2V, with a boost driver.

For that matter, the ST Drive actually won't always work either, because technically it requires a VIN of 4.5V for that IC to operate. It sometimes works on less than that. But in practice, I'm growing to hate those ICs.

I was convinced it could buck aswell -.-

So i see the picture now. How would you feed a LOC with 500mA in a 14500 host? Plz you cannot split the batt in two
Theres an LED driver that does that perfectly, it´s the "4Pack" driver. Its the only way i see under 2$ hehe.

 

[lazeerer]

Thermal tape. If i remember right, lazeerer used it in his 2W build, around the module. But i guess you can wrap it around the sink, if your dealing with a press fit. "no problem" he said :beer:

Nope was not me.


There would be NO need for it since both pins on a 445nm diode is insulated already.:thinking:

The Only time i used it was with 660nm diodes and also recommend it a couple times for 660nm diode.

You got me mixed up with some.

But again this is a Boost drive and i see no point to use a Red diode with it.