HCMS-2975_13 Datasheet, PDF (16/16 Pages) AVAGO TECHNOLOGIES LIMITED – High Performance CMOS 5 x 7 Alphanumeric Displays

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 D₅ = L, BIT D₄ = L) and
the PWM is set to 60% duty factor (BIT D₃ = H, BIT D₂
= H, BIT D₁ = L, BIT D₀ = H). The resulting brightness is
44% (.73 x .60 = .44) of full scale.
The temperature of the display will also affect the LED
bright­ness as shown in Figure 5.
3.0
2.6
HER/ORANGE
2.2
YELLOW
1.8
GREEN
1.4
AlGaAs
1.0
0.6
0.2
-55 -35 -15 5 25 45 65 85
T_A – AMBIENT TEMPERATURE – °C
Figure 5.
Appendix F. Reference Material
Application Note 1027: Soldering LED Components
Applica­tion Note 1015: Contrast Enhancement Techniques
for LED Displays
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Data subject to change. Copyright © 2007 Avago Technologies Limited. All rights reserved. Obsoletes 5989-3181EN
AV02-0699EN - September 18, 2007