Appendix E. Display Brightness
Two ways have been shown to control the brightness
of this LED display: setting the peak current and setting
the duty factor. Both values are set in Control Word 0.
To compute the resulting display brightness when both
PWM and peak current control are used, simply multi-
ply the two relative brightness factors. For example, if
Control Register 0 holds the word 1001101, the peak
current is 73% of full scale (BIT D
5
= L, BIT D
4
= L) and
the PWM is set to 60% duty factor (BIT D
3
= H, BIT D
2
= H, BIT D
1
= L, BIT D
0
= H). The resulting brightness is
44% (.73 x .60 = .44) of full scale.
The temperature of the display will also aect the LED
brightness as shown in Figure 5.
Appendix F. Reference Material
Application Note 1027: Soldering LED Components
Application Note 1015: Contrast Enhancement Techniques
for LED Displays
Figure 5.
RELATIVE LUMINOUS INTENSITY
(NORMALIZED TO 1 AT 25°C)
YELLOW
HER/ORANGE
0.2
-55
T
A
– AMBIENT TEMPERATURE – °C
3.0
2.6
2.2
1.8
1.4
1.0
0.6
856545255-15-35
GREEN
AlGaAs
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Data subject to change. Copyright © 2007 Avago Technologies Limited. All rights reserved. Obsoletes 5989-3181EN
AV02-0699EN - September 18, 2007
