HFBR-14E6TC 查看數據表（PDF） - HP => Agilent Technologies
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HFBR-14E6TC
HP => Agilent Technologies
HFBR-14E6TC Datasheet PDF : 25 Pages
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5 MBd Logic Link Design
If resistor R1 in Figure 2 is 70.4
W, a forward current IF of 48 mA
is applied to the HFBR-14x4
LED transmitter. With IF = 48
mA the HFBR-14x4/24x2 logic
link is guaranteed to work with
62.5/125 µm fiber optic cable
over the entire range of 0 to
1750 meters at a data rate of dc
to 5 MBd, with arbitrary data
format and pulse width
distortion typically less than
25%. By setting R1 = 115 W, the
transmitter can be driven with
IF = 30 mA, if it is desired to
economize on power or achieve
lower pulse distortion.
The following example will
illustrate the technique for
selecting the appropriate value
of IF and R1.
Maximum distance required =
400 meters. From Figure 3 the
drive current should be 15 mA.
From the transmitter data VF =
1.5 V (max.) at IF = 15 mA as
shown in Figure 9.
R1 = VCC − VF = 5V −1.5V
IF
15 mA
R1 = 233 Ω
The curves in Figures 3, 4, and 5
are constructed assuming no
inline splice or any additional
system loss. Should the link
consists of any in-line splices,
these curves can still be used to
calculate link limits provided
they are shifted by the
additional system loss expressed
in dB. For example, Figure 3
indicates that with 48 mA of
transmitter drive current, a 1.75
km link distance is achievable
with 62.5/125 µm fiber which
has a maximum attenuation of 4
dB/km. With 2 dB of additional
system loss, a 1.25 km link
distance is still achievable.
+5 V
SELECT R1 TO SET IF
R1
IF
2
6
1 KΩ
7
3
HFBR-14xx
TRANSMITTER
T
DATA IN
½ 75451
NOTE:
IT IS ESSENTIAL THAT A BYPASS CAPACITOR (0.01 µF TO 0.1 µF
CERAMIC) BE CONNECTED FROM PIN 2 TO PIN 7 OF THE RECEIVER.
TOTAL LEAD LENGTH BETWEEN BOTH ENDS OF THE CAPACITOR
AND THE PINS SHOULD NOT EXCEED 20 MM.
TRANSMISSION
DISTANCE =
Figure 2. Typical Circuit Configuration.
HFBR-24x2
RECEIVER
2
R6
7&3
TTL DATA OUT
RL
VCC
0.1 µF
11
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