IF peak Max.
IF Max.
21
LED lamps
Determine the pulse drive conditions as follows.
1. Decide what repetition frequency (f) and duty factor
(DF) will be used.
2. Determine the maximum tolerable peak current ratio
from Figure 2.
3. Determine the maximum forward current from
Figure 3.
For example, when Ta = 40
_C or above, the maximum
forward current (IF Max.) decreases.
4. Calculate the maximum tolerable peak current (IF
peak Max.).
Example
If f = 1 kHz, DF = 10%, and Ta = 40
_C, the maximum toler-
able peak current ratio from Figure 2 is 3.0 for red, orange
and yellow, and 2.4 for green.
The maximum forward current IF Max. at Ta = 40
_C is 20
mA for red, orange and yellow, and 25 mA for green.
Therefore, the maximum tolerable peak current under
these conditions is as follows :
FRed, orange and yellow
20 mA
3.0 = 60 mA
. .
FGreen
25 mA
2.4 = 60 mA
. . . . . . . . . . . . . . . . . .
For the repetition frequency, we recommend 1 kHz or
above.
(7)
Decrease of rated current
The maximum rated forward current of LED lamps will
vary depending on the ambient operating temperature.
(Refer to Figure 3)
(8)
Variation of luminous intensity depending on ambi-
ent temperature
ROHM LED lights have a temperature coefficient of
approximately –1% for red and orange, and
* 0.5% for
yellow and green. (Refer to the luminous intensity vs.
case temperature characteristics for each LED type.)
FStorage precautions
Storage in a dry box is best. However, if this is not pos-
sible we recommend the following conditions :
Temperature : 5 to 30
_C
Humidity : 60%RH max.
FRecommended PCB
We recommend the following hole diameters. Note, how-
ever, that these may vary depending on the board materi-
al, degree of integration, and wiring.
FLED lamp product names
The product names of ROHM LED lamps and chip LEDs
are coded as follows :