same I but different V

[Volter]

Hi,
If I got LEDs in series of different V (3V,3V,3V,2V,2V) values but same I (500mA) will they get the same current through?
Thanks.

[jwax]

You'll find the current in a series circuit is constant, once you apply sufficient voltage across the string.

[Bob Scott]

Hi,
If I got LEDs in series of different V (3V,3V,3V,2V,2V) values but same I (500mA) will they get the same current through?
Thanks.

Yes, if they are in series, the same amount of current must flow through all LEDs. It's like a river. The same amount of water must flow past all points.

I am just curious; which school did you attend to get your EET diploma?

[Bigglez]

If I got LEDs in series of I (500mA)

Is that a typo? 500mA is too high for common LEDs.
Are these Lumileds or other high watters?

if V = 3V, I = 0.5A, P= 1.5Watts!

[MrAl]

Hi,
If I got LEDs in series of different V (3V,3V,3V,2V,2V) values but same I (500mA) will they get the same current through?
Thanks.

The same current flows though each device in a series circuit.
If you have them connected end to end this will work out.
Any other way requires each LED to have its own resistor.

[Volter]

For Bob, is it OK to verify what I might know? Also, I got into software engineering and so haven’t done any EET for quite a time. That is why I kind of making sure I am not doing something I should not do. I might have more similar questions just to make sure I destroy the least of what I make!
On the other side I wanted to know more about the V across the LEDs since I would like to drive the LEDs with one driver.
Thanks guys anyway!

[Bigglez]

I wanted to know more about the V across the LEDs since I would like to drive the LEDs with one driver.

A series circuit, with common current in a single branch
has the least parts, but the LEDs would give different
light levels unless they are all of the same brand and
colour (i.e. same part number). Higher source voltage
is required.

A parallel circuit, with ballast resistors per LED has
the most versatility. The driver in this case would be
low impedance to have the least disruptive effect on
the separate LED branches.

[Volter]

Thank you Bigglez, that is what I am looking for! My apologies for not being clear, that happens often when I do not know too many answers.
I was considering a Buck circuit to build this driver circuit. Would you suggest a design circuit to fit your recommendation?
Thanks!

[Bigglez]

I was considering a Buck circuit to build this driver circuit. Would you suggest a design circuit to fit your recommendation?

A lot depends upon how much raw DC voltage you
have to start with, and how many LEDs.

A buck converter has lower out voltage then in
A boost converter has higher out voltage than in
A buck-boost does both but has inverted polarity*
A SEPIC converter covers all possibilities, but is complex.

*Two converters in cascade can 'double-invert' to
regain the first polarity and offer both boost and
buck operation.

Use the above links for reference. Here's a good
primer Ap Note on LED drivers from Maxim.

[Volter]

SO, you want me to go thru all those CALCULATIONS and all what it takes to come up with the design! Well, I guess I do not have much choice and so I will plunge into sometimes to night.
Thanks.

[Bigglez]

SO, you want me to go thru all those CALCULATIONS and all what it takes to come up with the design! Well, I guess I do not have much choice and so I will plunge into sometimes to night.

Use the above links for reference. Here's a good
primer Ap Note on LED drivers from Maxim.

Reading those materials is optional. However, you haven't
told us what you want to do with your LED(s).

[Volter]

I would like to built a fixture for something that could be a cheaper alternative to something that is already out there if I will have enough luck. So, at the moment I would like to avoid going into too many details if that’s OK.
Thanks.