Laser pointer discussion. Read/write reviews of laser pointers and laser pointer companies. Learn about all types of laser pointers and lasers





Welcome to Laser Pointer Forums! If you are looking for a laser pointer or want to compare different laser pointer companies, you may want to check out the LPF Laser Pointer Company Database. The link will open in a new window for your convenience.








Green Laser Pointers by Category Blue Laser Pointers by Category Red Laser Pointers by Category
Yellow Laser Pointers by Category Violet Laser Pointers by Category Orange Laser Pointers by Category
Top Laser Pointers by Power - 1 Watt+ Top Laser Pointers by Power - 500mW+ Top Laser Pointers by Power - 250mW+
Laser Pointer Database High Power Laser Pointers Laser Pointer Diodes
Laser Technology Laser Pointer Parts Lasers by Wavelength
Top 10 Laser Pointer Companies Laser Pointer Company Database Visible Beam Laser Pointers


One laser store meets all your needs

























Go Back   Laser Pointer Forums - Discuss Laser Pointers > Lasers > Drivers, Test-load, Power Supply, & Batteries



LPF List of Laser Pointer Companies (link opens new window)



Reply
 
LinkBack Thread Tools Display Modes
Old 11-12-2013, 11:17 PM #1
FalloutBe's Avatar
Member
 
Join Date: Nov 2013
Posts: 39
Rep Power: 0
FalloutBe is on a distinguished road
FalloutBe FalloutBe is offline
Member
FalloutBe's Avatar
 
Join Date: Nov 2013
Posts: 39
Rep Power: 0
FalloutBe is on a distinguished road
Default Switching regulator that regulates current instead of voltage?

Hello,


I was scouting Linear Technology's ICs to find a switching regulator which regulates the output current, as required for laser diode drivers.
(alternative: Maxim Integrated)

Preferably I want a regulator which doesn't need an inductor to operate. I read that charge pumps might be what I'm looking for.
However the charge pumps I found mostly have low input voltage requirements which is a problem since the power supply will be 9VDC.
Those which DO accept over 9V input voltage, can deliver only 250mA output, which is not enough.

If this is Really not possible, the best alternative will be a Buck regulator.

The problem is that all these ICs that I find regulate output voltage? But I need to regulate the output current, as I read in the sticky post on this board.
Are there ICs out there that regulate output current? Or am I supposed to add some things to the IC to trick it into regulating current?

I have built a lot of linear current regulators which dissipate a lot of heat in the power converter.
9V input voltage, 400mA output @ 2V is sadly a lot of wasted energy since the other 7V needs to be dissipated.
This is why I finally want to try and build one which uses a switched regulator.

List of my requirements:
- No inductors
- 9-15V input voltage
- Current regulation
- ~0mA to >700mA Output current

Not many requirements, but sadly I can't find any regulator which matches all of this.



I see people here on the forums building epically small buck drivers, and I can't help myself going crazy about understanding how it's possible that they can make it so small, and with so less components..
Are those drivers current regulators?

Now I don't need one of those, what I want is to be able to build a driver myself, and most importantly, to understand how this can be done.
There is no need for the driver to be this small. I'm always happy to use T7 or T5 packages because I can't work with DFN, SO, MS, .. packages. I don't have the skills to solder them.


Any ideas?



Last edited by FalloutBe; 11-12-2013 at 11:41 PM.
FalloutBe is offline   Reply With Quote







LPF List of Laser Pointer Companies (link opens new window)







Old 11-13-2013, 01:42 AM #2
djQUAN's Avatar
Class 3R Laser
 
Join Date: May 2013
Location: Philippines
Posts: 1,128
Rep Power: 559
djQUAN has a reputation beyond reputedjQUAN has a reputation beyond reputedjQUAN has a reputation beyond reputedjQUAN has a reputation beyond reputedjQUAN has a reputation beyond reputedjQUAN has a reputation beyond reputedjQUAN has a reputation beyond reputedjQUAN has a reputation beyond reputedjQUAN has a reputation beyond reputedjQUAN has a reputation beyond reputedjQUAN has a reputation beyond repute
Send a message via Yahoo to djQUAN
djQUAN djQUAN is offline
Class 3R Laser
djQUAN's Avatar
 
Join Date: May 2013
Location: Philippines
Posts: 1,128
Rep Power: 559
djQUAN has a reputation beyond reputedjQUAN has a reputation beyond reputedjQUAN has a reputation beyond reputedjQUAN has a reputation beyond reputedjQUAN has a reputation beyond reputedjQUAN has a reputation beyond reputedjQUAN has a reputation beyond reputedjQUAN has a reputation beyond reputedjQUAN has a reputation beyond reputedjQUAN has a reputation beyond reputedjQUAN has a reputation beyond repute
Send a message via Yahoo to djQUAN
Default Re: Switching regulator that regulates current instead of voltage?

A charge pump is basically a switched capacitor converter. A capacitor carries charge from the input to the output. For step up charge pumps, a cap is basically charged in parallel with the input and discharged in series and vice versa for step down. It is quite efficient for low currents and if the output is a multiple of the input. There are charge pumps IIRC that are designed for driving LED backlights but still have the low current limitation. It's inherent for charge pumps since you are limited by the switch on resistances and the size and ESR of the flying capacitor.

If you want higher currents, there's no way but to use inductors. Why are you afraid of them anyways? you can always find one in scrap boards and rewind them to get other values.
djQUAN is offline   Reply With Quote
Old 11-13-2013, 04:34 AM #3
Cyparagon's Avatar
Class 4 Laser
 
Join Date: Sep 2007
Location: Wisconsin
Posts: 9,144
Rep Power: 9321
Cyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond repute
Cyparagon Cyparagon is online now
Class 4 Laser
Cyparagon's Avatar
 
Join Date: Sep 2007
Location: Wisconsin
Posts: 9,144
Rep Power: 9321
Cyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond repute
Default Re: Switching regulator that regulates current instead of voltage?

Switching regulators rely on inductance for their operation, so requiring no inductors is silly.
You can get ICs with internal inductors, but their current capacity is very low.

Remove the no-inductors requirement and search again.
__________________
A problem well stated is a problem half solved.
Cyparagon is online now   Reply With Quote
Old 11-13-2013, 07:07 AM #4
The Lightning Stalker's Avatar
Class 3B Laser
 
Join Date: Aug 2013
Location: MI, US
Posts: 2,654
Rep Power: 716
The Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond repute
The Lightning Stalker The Lightning Stalker is offline
Class 3B Laser
The Lightning Stalker's Avatar
 
Join Date: Aug 2013
Location: MI, US
Posts: 2,654
Rep Power: 716
The Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond repute
Default Re: Switching regulator that regulates current instead of voltage?

There is no way to avoid using an inductor. It isn't possible to regulate current with a charge pump
because the instantaneous current through a capacitor tends to go toward infinity. In a real capacitor, it
is only limited by the ESR of the capacitor and resistances in whatever is connected to it (actually stray
inductances as well, but they are insignificant. So technically a charge pump actually contains
inductors(!) and avoiding them is completely impossible(!!)) Anyway, that resistance will convert the
power directly into heat and take out the weakest link. So many poor defenseless little electronic
components have been sacrificed to gain this knowledge.
__________________
ALL NEW MEMBERS MUST READ THIS!!! --> http://www.laserpointersafety.com

"Where, now, is the way by which the light distributes itself" - Job 38:24

YouTube Channel
The Lightning Stalker is offline   Reply With Quote
Old 11-13-2013, 09:17 AM #5
FalloutBe's Avatar
Member
 
Join Date: Nov 2013
Posts: 39
Rep Power: 0
FalloutBe is on a distinguished road
FalloutBe FalloutBe is offline
Member
FalloutBe's Avatar
 
Join Date: Nov 2013
Posts: 39
Rep Power: 0
FalloutBe is on a distinguished road
Default Re: Switching regulator that regulates current instead of voltage?

Alright, forget the 'no inductor' requirement.
I've also found a lot of ICs with built in inductors, which do go up to high currents such as 1-2A! Fantastic ^^

Now the problem still remains: they are voltage regulators?!

About the different packages: It seems like the larger packages such as T5, T7, N8,.. always have a much larger 'minimum output voltage' (~4V) in contrary to the ~0.1-0.5V which I find for the smaller packages, why is this?
It's a big problem for me because I can't solder these small packages, but the large packages become useless if they output a minimum of 4V to the diode.

Last edited by FalloutBe; 11-13-2013 at 09:22 AM.
FalloutBe is offline   Reply With Quote
Old 11-13-2013, 01:04 PM #6
Leodahsan's Avatar
Class 3R Laser
 
Join Date: Aug 2010
Location: Rio Grande do Sul, Brazil
Posts: 2,088
Rep Power: 165
Leodahsan has a reputation beyond reputeLeodahsan has a reputation beyond reputeLeodahsan has a reputation beyond reputeLeodahsan has a reputation beyond reputeLeodahsan has a reputation beyond reputeLeodahsan has a reputation beyond reputeLeodahsan has a reputation beyond reputeLeodahsan has a reputation beyond reputeLeodahsan has a reputation beyond reputeLeodahsan has a reputation beyond reputeLeodahsan has a reputation beyond repute
Leodahsan Leodahsan is offline
Class 3R Laser
Leodahsan's Avatar
 
Join Date: Aug 2010
Location: Rio Grande do Sul, Brazil
Posts: 2,088
Rep Power: 165
Leodahsan has a reputation beyond reputeLeodahsan has a reputation beyond reputeLeodahsan has a reputation beyond reputeLeodahsan has a reputation beyond reputeLeodahsan has a reputation beyond reputeLeodahsan has a reputation beyond reputeLeodahsan has a reputation beyond reputeLeodahsan has a reputation beyond reputeLeodahsan has a reputation beyond reputeLeodahsan has a reputation beyond reputeLeodahsan has a reputation beyond repute
Default Re: Switching regulator that regulates current instead of voltage?

Maybe searching for buck / boost LED drivers IC's may give you some results? You just need to scope the output and check if theres smooth turn on, hows regulation (current out error in %). I didn't build any switch mode drivers, but I've always wanted to.

Subscribing to thread
__________________
Any doubts, feel free to PM ou send me a visitor message! I'll help as I can.

Best regards,
Leonardo
__________________

* Deploying CNC router project soon...

DONATE!
The smallest donation will help, if you like this enormous information resource, just do it.
Leodahsan is offline   Reply With Quote
Old 11-13-2013, 03:49 PM #7
Cyparagon's Avatar
Class 4 Laser
 
Join Date: Sep 2007
Location: Wisconsin
Posts: 9,144
Rep Power: 9321
Cyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond repute
Cyparagon Cyparagon is online now
Class 4 Laser
Cyparagon's Avatar
 
Join Date: Sep 2007
Location: Wisconsin
Posts: 9,144
Rep Power: 9321
Cyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond repute
Default Re: Switching regulator that regulates current instead of voltage?

A 2A buck regulator IC with internal inductor? This I gotta see.

Regulators are only trying to get a specific voltage on a feedback pin. You can vary the voltage or the current by varying the ratio that the output has to this expected feedback voltage. Google the LM317 for a simple example. Compare the voltage and current modes of operation.

You can convert the current to a voltage using a shunt. You can then amplify that voltage to match the feedback requirements of the IC using many different methods.
__________________
A problem well stated is a problem half solved.
Cyparagon is online now   Reply With Quote
Old 11-13-2013, 08:50 PM #8
FalloutBe's Avatar
Member
 
Join Date: Nov 2013
Posts: 39
Rep Power: 0
FalloutBe is on a distinguished road
FalloutBe FalloutBe is offline
Member
FalloutBe's Avatar
 
Join Date: Nov 2013
Posts: 39
Rep Power: 0
FalloutBe is on a distinguished road
Default Re: Switching regulator that regulates current instead of voltage?

Quote:
Originally Posted by Leodahsan View Post
Maybe searching for buck / boost LED drivers IC's may give you some results? You just need to scope the output and check if theres smooth turn on, hows regulation (current out error in %). I didn't build any switch mode drivers, but I've always wanted to.

Subscribing to thread
http://www.linear.com/product/LT3517
This is probably something I'm looking for, but it does not have an internal switch.
Also, why are these packages so tiny? 4mm wide?! how am I supposed to solder this, my soldering iron tip is like 5mm wide.



Quote:
Originally Posted by Cyparagon View Post
A 2A buck regulator IC with internal inductor? This I gotta see.
Linear Technology - Parametric Search for Step-Down (Buck) Regulators with Internal Inductor
They even go up to 36A

Quote:
Originally Posted by Cyparagon View Post
Regulators are only trying to get a specific voltage on a feedback pin. You can vary the voltage or the current by varying the ratio that the output has to this expected feedback voltage. Google the LM317 for a simple example. Compare the voltage and current modes of operation.

You can convert the current to a voltage using a shunt. You can then amplify that voltage to match the feedback requirements of the IC using many different methods.
Thank you for explaining how to make the current regulation!
Sadly the packages with internal inductors don't have the feedback pin because that's also internal :/

Last edited by FalloutBe; 11-13-2013 at 09:06 PM.
FalloutBe is offline   Reply With Quote
Old 11-13-2013, 09:09 PM #9
The Lightning Stalker's Avatar
Class 3B Laser
 
Join Date: Aug 2013
Location: MI, US
Posts: 2,654
Rep Power: 716
The Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond repute
The Lightning Stalker The Lightning Stalker is offline
Class 3B Laser
The Lightning Stalker's Avatar
 
Join Date: Aug 2013
Location: MI, US
Posts: 2,654
Rep Power: 716
The Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond repute
Default Re: Switching regulator that regulates current instead of voltage?

Quote:
Originally Posted by FalloutBe View Post
Sadly the packages with internal inductors don't have the feedback pin because that's also internal :/
Sure they do. Take a look at the LTM8050, for instance.
__________________
ALL NEW MEMBERS MUST READ THIS!!! --> http://www.laserpointersafety.com

"Where, now, is the way by which the light distributes itself" - Job 38:24

YouTube Channel
The Lightning Stalker is offline   Reply With Quote
Old 11-13-2013, 09:19 PM #10
FalloutBe's Avatar
Member
 
Join Date: Nov 2013
Posts: 39
Rep Power: 0
FalloutBe is on a distinguished road
FalloutBe FalloutBe is offline
Member
FalloutBe's Avatar
 
Join Date: Nov 2013
Posts: 39
Rep Power: 0
FalloutBe is on a distinguished road
Default Re: Switching regulator that regulates current instead of voltage?

Quote:
Originally Posted by The Lightning Stalker View Post
Sure they do. Take a look at the LTM8050, for instance.
Quote:
FB (Pin K7): The LTM8050 regulates its FB pin to 0.79V.
Connect the adjust resistor from this pin to ground.
The value of R FB is given by the equation
RFB = 394.21/(VOUT– 0.79), where RFB is in kΩ.
So I need to amplify the current signal from a sense resistor, into a resistive value? It would be a lot easier if the fb was an analog voltage input.

Last edited by FalloutBe; 11-13-2013 at 09:20 PM.
FalloutBe is offline   Reply With Quote
Old 11-13-2013, 09:28 PM #11
The Lightning Stalker's Avatar
Class 3B Laser
 
Join Date: Aug 2013
Location: MI, US
Posts: 2,654
Rep Power: 716
The Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond repute
The Lightning Stalker The Lightning Stalker is offline
Class 3B Laser
The Lightning Stalker's Avatar
 
Join Date: Aug 2013
Location: MI, US
Posts: 2,654
Rep Power: 716
The Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond repute
Default Re: Switching regulator that regulates current instead of voltage?

It is an analog voltage input. When it hits 0.79V it shuts off.
__________________
ALL NEW MEMBERS MUST READ THIS!!! --> http://www.laserpointersafety.com

"Where, now, is the way by which the light distributes itself" - Job 38:24

YouTube Channel
The Lightning Stalker is offline   Reply With Quote
Old 11-13-2013, 10:26 PM #12
FalloutBe's Avatar
Member
 
Join Date: Nov 2013
Posts: 39
Rep Power: 0
FalloutBe is on a distinguished road
FalloutBe FalloutBe is offline
Member
FalloutBe's Avatar
 
Join Date: Nov 2013
Posts: 39
Rep Power: 0
FalloutBe is on a distinguished road
Default Re: Switching regulator that regulates current instead of voltage?

Ooooh so the FB resistor that you must add, creates a voltage divider together with the 499k resistor?

Is it still possible then to have the output of the OpAmp connected to this pin?
Because that would mean that the OpAmp output is connected to Vout trough the 499k resistor. Isn't that bad?
FalloutBe is offline   Reply With Quote
Old 11-13-2013, 10:35 PM #13
The Lightning Stalker's Avatar
Class 3B Laser
 
Join Date: Aug 2013
Location: MI, US
Posts: 2,654
Rep Power: 716
The Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond repute
The Lightning Stalker The Lightning Stalker is offline
Class 3B Laser
The Lightning Stalker's Avatar
 
Join Date: Aug 2013
Location: MI, US
Posts: 2,654
Rep Power: 716
The Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond repute
Default Re: Switching regulator that regulates current instead of voltage?

No no, you would connect the sensing resistor to ground in series with the load. Then FB would connect
at the node between the resistor and load. It would require some experimentation. These modules aren't
cheap either, like $45 apiece, but I don't know what your budget is.
__________________
ALL NEW MEMBERS MUST READ THIS!!! --> http://www.laserpointersafety.com

"Where, now, is the way by which the light distributes itself" - Job 38:24

YouTube Channel
The Lightning Stalker is offline   Reply With Quote
Old 11-13-2013, 10:39 PM #14
FalloutBe's Avatar
Member
 
Join Date: Nov 2013
Posts: 39
Rep Power: 0
FalloutBe is on a distinguished road
FalloutBe FalloutBe is offline
Member
FalloutBe's Avatar
 
Join Date: Nov 2013
Posts: 39
Rep Power: 0
FalloutBe is on a distinguished road
Default Re: Switching regulator that regulates current instead of voltage?

Oh like that!
So to choose the output current, I simply change the sensing resistor into a POT?
(however I'm not sure there are like 0.1ohm pots)

EDIT: I calculated the sensing pot, and would have to be a 5or10ohm pot.

And indeed.. That is way too expensive. I was thinking about €5 or something ^^



How about we go back a step. This Ámodule stuff actually isn't even what I'm looking for.
let's go back to larger components such as the TO220 packages ^^ It's no problem if the driver gets larger.
This one for example:
http://www.linear.com/product/LT1959
(found in this list, and sorting by 'minimum output voltage) because that needs to be low, right?)

The feedback pin on this component:
Quote:
FB:
The feedback pin is used to set output voltage using an
external voltage divider that generates 1.21V at the pin
with the desired output voltage. Three additional functions
are performed by the FB pin. When the pin voltage drops
below 0.8V, switch current limit is reduced. Below 0.7V
the external sync function is disabled and switching fre-
quency is reduced. See Feedback Pin Function section in
Applications Information for details
hmm isn't that "regulation" bad? it'll only react when it goes below a certain value.

Last edited by FalloutBe; 11-13-2013 at 10:54 PM.
FalloutBe is offline   Reply With Quote
Old 11-13-2013, 11:55 PM #15
The Lightning Stalker's Avatar
Class 3B Laser
 
Join Date: Aug 2013
Location: MI, US
Posts: 2,654
Rep Power: 716
The Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond repute
The Lightning Stalker The Lightning Stalker is offline
Class 3B Laser
The Lightning Stalker's Avatar
 
Join Date: Aug 2013
Location: MI, US
Posts: 2,654
Rep Power: 716
The Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond repute
Default Re: Switching regulator that regulates current instead of voltage?

Quote:
Originally Posted by FalloutBe View Post
Oh like that!
So to choose the output current, I simply change the sensing resistor into a POT?
(however I'm not sure there are like 0.1ohm pots)
You would need a high power pot. Instead use a regular sense resistor and put a 10k pot
across that. Adjusting the pot down would increase the current. You just have to be
careful not to bottom it out, or else it will max out and probably blow something. The thing
to do would be to connect another resistor to ground in series with the pot to set a fixed
minimum below which it cannot go.

Quote:
Originally Posted by FalloutBe View Post
Now you're talking.

Quote:
Originally Posted by FalloutBe View Post
(found in this list, and sorting by 'minimum output voltage) because that needs to be low, right?)
We're actually looking for a low reference voltage, but logic would dictate that a low output
voltage would equate to a low reference voltage. Reference voltage isn't usually on a
product selector anyway.

Quote:
Originally Posted by FalloutBe View Post
The feedback pin on this component:

hmm isn't that "regulation" bad? it'll only react when it goes below a certain value.
Not necessarily, but it might be undesirable. We are after all using this for purposes other
than what it was designed for. The only time the reference voltage will be in that range will
be during startup (and shutdown, but that don't count) and open load circuit conditions.If
you can find a "current-mode" regulator, that will work much better. CC switching
regulators need a load at all times, or else bad things happen.
__________________
ALL NEW MEMBERS MUST READ THIS!!! --> http://www.laserpointersafety.com

"Where, now, is the way by which the light distributes itself" - Job 38:24

YouTube Channel
The Lightning Stalker is offline   Reply With Quote
Old 11-14-2013, 12:13 AM #16
Cyparagon's Avatar
Class 4 Laser
 
Join Date: Sep 2007
Location: Wisconsin
Posts: 9,144
Rep Power: 9321
Cyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond repute
Cyparagon Cyparagon is online now
Class 4 Laser
Cyparagon's Avatar
 
Join Date: Sep 2007
Location: Wisconsin
Posts: 9,144
Rep Power: 9321
Cyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond repute
Default Re: Switching regulator that regulates current instead of voltage?

Quote:
Originally Posted by FalloutBe View Post
Those are not ICs. Those are DCDC converter modules which are basically an assembled circuit board.
__________________
A problem well stated is a problem half solved.
Cyparagon is online now   Reply With Quote
Reply





Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On











Loading








Green Laser Pointers by Category Blue Laser Pointers by Category Red Laser Pointers by Category
Yellow Laser Pointers by Category Violet Laser Pointers by Category Orange Laser Pointers by Category
Top Laser Pointers by Power - 1 Watt+ Top Laser Pointers by Power - 500mW+ Top Laser Pointers by Power - 250mW+
Laser Pointer Database High Power Laser Pointers Laser Pointer Diodes






Privacy Policy | Advertising Disclaimer | Terms of Use


 


All times are GMT. The time now is 01:13 PM.


Powered by: vBulletin
Copyright ©2000 - 2017, Jelsoft Enterprises Ltd.
Search Engine Friendly URLs by vBSEO
Privacy Policy | Advertising Disclaimer | Terms of Use
Copyright (C) 2017 Laser Pointer Forums, LLC