LED current consumption
Archiver
Posts: 46,084
I have some LEDs that I need to turn on and I need to know how current is
affected by connecting them in series and in parallel. Each LED operates
from 3.2 to 4 VDC and is rated at 30ma of current. How much current does it
draw if 3 of them are connected in parallel? in series? assuming I have a
4VDC power supply? How is brightness affected? I know this is lot, but I
would greatly appreciate any feedback? Thank you.
-Sean
[noparse][[/noparse]Non-text portions of this message have been removed]
affected by connecting them in series and in parallel. Each LED operates
from 3.2 to 4 VDC and is rated at 30ma of current. How much current does it
draw if 3 of them are connected in parallel? in series? assuming I have a
4VDC power supply? How is brightness affected? I know this is lot, but I
would greatly appreciate any feedback? Thank you.
-Sean
[noparse][[/noparse]Non-text portions of this message have been removed]
Comments
Remember that in series they will all have the same current (whatever
you limit it to with an external resistor) but their voltage drops will
add up. So 3 3V LEDs in series will drop 9V. With a 12V battery that
would leave you 3V across the resistor.
In parallel, the current is separate for each, but the voltage is the
same. So 3 3V LEDs in parallel still drop 3V. But the current through
each is separate.
Al Williams
AWC
* Control 8 servos at once
http://www.al-williams.com/awce/pak8.htm
>
Original Message
> From: sean975@a... [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=8o1aRJjtOSve2u_TE3Bvf2YeOBywuc4uGRXLBD_2FeykBjOnI2EQXVzpjPeU93n9zqi4swnx_hUaaQ]sean975@a...[/url
> Sent: Wednesday, June 12, 2002 1:23 PM
> To: basicstamps@yahoogroups.com
> Subject: [noparse][[/noparse]basicstamps] LED current consumption
>
>
> I have some LEDs that I need to turn on and I need to know
> how current is
> affected by connecting them in series and in parallel. Each
> LED operates
> from 3.2 to 4 VDC and is rated at 30ma of current. How much
> current does it
> draw if 3 of them are connected in parallel? in series?
> assuming I have a
> 4VDC power supply? How is brightness affected? I know this
> is lot, but I
> would greatly appreciate any feedback? Thank you.
> -Sean
>
>
> [noparse][[/noparse]Non-text portions of this message have been removed]
>
>
> To UNSUBSCRIBE, just send mail to:
> basicstamps-unsubscribe@yahoogroups.com
> from the same email address that you subscribed. Text in the
> Subject and Body of the message will be ignored.
>
>
> Your use of Yahoo! Groups is subject to
> http://docs.yahoo.com/info/terms/
>
In parallel each LED will draw will require typically 5 - 20mA each, the
more LEDS, the more current. In series, the total current will be the
same as the current flowing through one LED, but the supply voltage will
need to be higher, to allow for approx 2V drop per LED. With a 4V supply
you can only realistically power LEDs in parallel. You will need to
insert a resistor in series with each LED to limit current. So for a LED
with say, 10mA Current the following applies: ((V supply (4volts)) - (V
LED volt drop (2 volts)))/ LED drive current (0.01A) = 2/.01 = 200 ohms.
Power dissipation in resistor = 2V * .01A = .02 Watts. Brightness is
affected by the amount of current through the LED, BUT doubling the
current will not double the amount of visible light output. 10mA is OK
for 5mm STD LEDS. The above uses generalizations and typical values and
should get you in the right ballpark.
Rob
Original Message
From: sean975@a... [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=t8AxVxE2JHJ8ybkFprklqnYhUOnOAwMipmKfvAWOqdQooDbOakCkHQrWlHstbwQWDFsybVXdDQpqjw]sean975@a...[/url
Sent: 12 June 2002 19:23
To: basicstamps@yahoogroups.com
Subject: [noparse][[/noparse]basicstamps] LED current consumption
I have some LEDs that I need to turn on and I need to know how current
is
affected by connecting them in series and in parallel. Each LED
operates
from 3.2 to 4 VDC and is rated at 30ma of current. How much current
does it
draw if 3 of them are connected in parallel? in series? assuming I have
a
4VDC power supply? How is brightness affected? I know this is lot, but
I
would greatly appreciate any feedback? Thank you.
-Sean
[noparse][[/noparse]Non-text portions of this message have been removed]
To UNSUBSCRIBE, just send mail to:
basicstamps-unsubscribe@yahoogroups.com
from the same email address that you subscribed. Text in the Subject
and Body of the message will be ignored.
Your use of Yahoo! Groups is subject to
http://docs.yahoo.com/info/terms/