RGB LED PCB Assembly Instructions & Technical Manual
Description
The RGB MR-16 PCB is a LED-based luminaire which can be easily customized with the following options:
➡
Three-colour light assembly using 3 or 6 LEDs per colour;
➡
Single-colour light assembly using either 9 or 18 LEDs in your choice of colour;
➡
Use either 2-pin 5mm or 4-pin Piranha-style (single-colour) LEDs.
PCBs are populated with each colour having two sets of three LEDs with a single current-limiting resistor per set.
Any LED colour is possible but the basic RGB kit comes with six red, six blue, and six green 5mm LEDs while the
white kit comes with 18 5mm LEDs.
The resistors included with our kits are intended for 12V operation and will produce approximately 20mA per set of
three LEDs for a total of 120mA per board with 18 LEDs installed. It is possible to operate with other voltages as long
as the minimum power supply voltage is greater than the sum of the individual LED forward voltages (e.g., with red
LEDs where V
f
= 2.0 V, the minimum voltage would be 6V for each set of LEDs). For a 20mA current in each LED
string, the appropriate resistor value for each set of three LEDs, R, is calculated from:
R
=
50(
V
b
−
3
V
f
)
For this example V
b
= 8V, so the resistor value would be 50(8-6) = 100
Ω
. Select the closest available resistor which is
greater than or equal to the desired value. If installing in an automotive application, please be aware that the battery
voltage can vary by up to 15V so use this value for the V
b
value.
The red, green, blue, and white LEDs included with our kits have the following V
f
values:
L E D
T Y P I C A L V
f
1 2 V R E S I S TO R
Red (RGB Kit)
2.0V
300
Ω
Green (RGB Kit)
3.2V
120
Ω
Blue (RGB Kit)
3.0V
150
Ω
White (White Kit)
3.2V
120
Ω
If you require different resistors, be sure to use only the
¼
watt miniature resistors (i.e., 1.70mm x 3.20mm)—other
resistors are too large to fit on this PCB.
Another consideration that will limit the maximum voltage is the power rating of the resistors. The worst-case power
dissipation in the red resistors (
¼
W) limits the maximum voltage to:
This maximum voltage can be increased by either placing the red LED strings in series or using another LED in place
of the red with a higher V
f
value. Refer to the
below
.
V
max
=
25
2
+
3
V
f
=
18.5
C o m p u t e r I n s p i r a t i o n s
!
A s s e m b l y & Te c h n i c a l M a n u a l
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