Issue B.2 07/08

Page 7 of 14

OPTEK reserves the right to make changes at any time in order to improve design and to supply the best product possible.

OPTEK Technology Inc. —

1645 Wallace Drive, Carrollton, Texas 75006

Phone: (972) 323-2200 or (800) 341-4747 FAX: (972) 323-2396 visibleLED@optekinc.com www.optekinc.com

Lednium Series Optimal X

OVTL09LG3x Series

Spatial Intensity Distribution

Normalized Spectral Intensity vs Angular Displacement

Angle (degrees)

-

-80

-60

-40

-20

0

20

40

60

80

100

In the diagram below if each parallel group of three LEDs is a single color the luminous flux produced is a

mixture or R + G + B. To change the emission level of any group (color), and therefore the color of the mixed light,

the current passing through each group must be changed, yet the circuit current remains a constant value. The

means of doing this is to shunt current away from a group while allowing the total circuit current to remain constant.

By controlling the operating point of the three shunt transistors, the operating current of each group of LEDs

can be independently and continuously adjusted. The transistors will turn OFF (short across) each strip individually

when they are ON. The frequency for PWMs should be high to eliminate flickering (more than 20KHz preferred).

Controlling the ON time for each strip will control the average intensity of each strip in order to color-mix the RGB

Turtle.

Red PWM

Green PWM

Blue PWN

R1 - 10K

Common

3

2

1

Current

Source

R1 - 10K

R1 - 10K

MGSF1N03LT1G

MGSF1N03LT1G

MGSF1N03LT1G

1

2

3

3

1

2

3

1

2

Dimming and color mixing for OVTL09LG3M