Electrical/Optical
These versatile bar graph arrays are composed of ten
light emitting diodes. The light from each LED is optically
stretched to form individual elements. The Red (HDSP-
4820) bar graph array LEDs use a p-n junction diffused
into a GaAsP epitaxial layer on a GaAs substrate. The Al-
GaAs Red (HLCP-J100) bar graph array LEDs use double
heterojunction AlGaAs on a GaAs substrate. HER (HDSP-
4830) and Yellow (HDSP-4840) bar graph array LEDs use
a GaAsP epitaxial layer on a GaP substrate. Green (HDSP-
4850) bar graph array LEDs use liquid phase GaP epi-
taxial layer on a GaP substrate. The multicolor bar graph
arrays (HDSP-4832/4836) have HER, Yellow, and Green
LEDs in one package. These displays are designed for
strobed operation. The typical forward voltage values
can be scaled from Figures 5 and 11. These values should
be used to calculate the current limiting resistor value
and typical power consumption. Expected maximum VF
values for driver circuit design and maximum power dis-
sipation may be calculated using the VFMAX models:
Standard Red HDSP-4820 series
VFMAX = 1.8 V + IPeak (10 :)
For: IPeak t 5 mA
AlGaAs Red HLCP-J100 series
VFMAX = 1.8 V + IPeak (20 :)
For: IPeak d 20 mA
VFMAX = 2.0 V + IPeak (10 :)
For: IPeak t 20 mA
HER (HDSP-4830) and Yellow
(HDSP-4840) series
VFMAX = 1.6 + IPeak (45 :)
For: 5 mA d IPeak d 20 mA
VFMAX = 1.75 + IPeak (38 :)
For: IPeak t 20 mA
Green (HDSP-4850) series
VFMAX = 2.0 + IPeak (50 :)
For: IPeak > 5 mA
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Data subject to change. Copyright © 2005-2009 Avago Technologies. All rights reserved. Obsoletes AV01-0277EN
AV02-1798EN - November 5, 2009
Figures 4 and 10 allow the designer to calculate the lu-
minous intensity at different peak and average currents.
The following equation calculates intensity at different
peak and average currents:
IVAVG = (IFAVG/IFAVG DATA
SHEET)Kpeak)(IVDATA SHEET)
Where:
IVAVG is the calculated time averaged luminous inten-
sity resulting from IFAVG.
IFAVG is the desired time averaged LED current.
IFAVG DATA SHEET is the data sheet test current for
IVDATA SHEET.
Kpeak is the relative efficiency at the peak current,
scaled from Figure 4 or 10.
IV DATA SHEET is the data sheet luminous intensity,
resulting from IFAVG DATA SHEET.
For example, what is the luminous intensity of an HDSP-
4830 driven at 50 mA peak 1/5 duty factor?
IFAVG = (50 mA) (0.2) = 10 mA
IFAVG DATA SHEET = 10 mA
Kpeak = 1.3
IV DATA SHEET = 3500 Pcd
Therefore
IVAVG = (10 mA/10 mA) (1.3) (3500 mcd) = 4550 mcd