LED
Infrared LED
L8957
Low cost LED ideal for optical encoders
L8957 is an infrared LED using a low-cost lens and available at a lower price than other products up to now.
Features
Applications
l
Low price
Uses low cost lens
l
Optical encoders
l
Optical switches
I
Absolute maximum ratings (Ta=25 °C, unless otherwise noted)
Parameter
Symbol
Reverse voltage
V
4
Forward current
I
.
Forward current reduction rate
-
Pulse forward current
I
.2
Pulse forward current reduction rate
-
Power dissipation
P
Operating temperature
Topr
Storage temperature
Tstg
Value
5
80
0.67
0.5
7
150
-30 to +85
-40 to +100
Unit
V
mA
mA/°C
A
mA/°C
mW
°C
°C
I
Electrical and optical characteristics (Ta=25 °C)
Parameter
Symbol
Condition
Min.
Typ.
Max.
Unit
Peak emission wavelength
I
.
=50 mA
840
870
900
nm
lp
Spectral half width
I
.
=50 mA
-
45
-
nm
Dl
Radiant flux
fe
I
.
=50 mA
3.4
5.8
-
mW
Forward voltage
V
.
I
.
=50 mA
-
1.6
1.75
V
Reverse current
I
4
V
4
=5 V
-
-
5
µA
Spot light size *
Bw I
.
=30 mA
4.5
5.0
-
mm
Optical output *
Pe
I
.
=30 mA
1.0
2.0
-
mW
!
Cut-off frequency *
fc
I
.
=30 mA ± 4 mAp-p
25
40
-
MHz
*1: Full width at half maximum, measurement distance (from the image sensor to the bottom surface of L8957s base)=10 mm
*2: Measurement distance [from the photodiode (active area:
f8
mm) to the bottom surface of L8957s base]=10 mm
*3: Frequency at which the optical output drops by -3 dB from that at 100 kHz.
1
HAMAMATSU [ HAMAMATSU CORPORATION ]
