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 V
F
values for driver circuit design and maximum power dis-
sipation may be calculated using the V
FMAX
models:
Standard Red HDSP-4820 series
V
F
MAX = 1.8 V + I
Peak
(10 :)
For: I
Peak
t 5 mA
AlGaAs Red HLCP-J100 series
V
F
MAX = 1.8 V + I
Peak
(20 :)
For: I
Peak
d 20 mA
V
F
MAX = 2.0 V + I
Peak
(10 :)
For: I
Peak
t 20 mA
HER (HDSP-4830) and Yellow
(HDSP-4840) series
V
F
MAX = 1.6 + I
Peak
(45 :)
For: 5 mA d I
Peak
d 20 mA
V
F
MAX = 1.75 + I
Peak
(38 :)
For: I
Peak
t 20 mA
Green (HDSP-4850) series
V
F
MAX = 2.0 + I
Peak
(50 :)
For: I
Peak
> 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:
I
V
AVG = (I
F
AVG/I
F
AVG DATA
SHEET)K
peak
)(I
V
DATA SHEET)
Where:
I
V
AVG is the calculated time averaged luminous inten-
sity resulting from I
F
AVG.
I
F
AVG is the desired time averaged LED current.
I
F
AVG DATA SHEET is the data sheet test current for
I
V
DATA SHEET.
K
peak
is the relative efficiency at the peak current,
scaled from Figure 4 or 10.
I
V
DATA SHEET is the data sheet luminous intensity,
resulting from I
F
AVG DATA SHEET.
For example, what is the luminous intensity of an HDSP-
4830 driven at 50 mA peak 1/5 duty factor?
I
F
AVG = (50 mA) (0.2) = 10 mA
I
F
AVG DATA SHEET = 10 mA
K
peak
= 1.3
I
V
DATA SHEET = 3500 Pcd
Therefore
I
V
AVG = (10 mA/10 mA) (1.3) (3500 mcd) = 4550 mcd
