HCMS-39X6 Datasheet, PDF (21/22 Pages) Agilent(Hewlett-Packard) – 3.3 V High Performance CMOS 5x7 AlphaNumeric Displays

Appendix E. Display
Brightness
Appendix F. Reference
Material
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 multiply
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.
Application Note 1027:
Soldering LED Components
Application Note 1015: Contrast
Enhancement Techniques for
LED Displays
The temperature of the display
will also affect the LED
brightness as shown in Figure 10.
3.0
2.5
2.0
1.5
1.0
0.5
0
-50
RED
GREEN
0
50
100
AMBIENT TEMPERATURE – °C
Figure 10. Relative luminous Intensity versus ambient temperature.
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