125 Megabaud Versatile Link
The Versatile Fiber Optic
Connection
Technical Data
Features
Data Transmission at Signal
Rates of 1 to 125 MBd over
Distances of 100 Meters
Compatible with Inexpen-
sive, Easily Terminated
Plastic Optical Fiber, and
with Large Core Silica Fiber
High Voltage Isolation
Transmitter and Receiver
Application Circuit Sche-
matics and Recommended
Board Layouts Available
Interlocking Feature for
Single Channel or Duplex
Links, in a Vertical or
Horizontal Mount
Configuration
Applications
Intra-System Links: Board-
to-Board, Rack-to-Rack
Telecommunications
Switching Systems
Computer-to-Peripheral
Data Links, PC Bus
Extension
Industrial Control
Proprietary LANs
Digitized Video
Medical Instruments
Reduction of Lightning and
Voltage Transient
Susceptibility
Description
The 125 MBd Versatile Link
(HFBR-0507 Series) is the most
cost-effective fiber-optic solution
for transmission of 125 MBd data
over 100 meters. The data link
consists of a 650 nm LED
transmitter, HFBR-15X7, and a
PIN/preamp receiver, HFBR-
25X6. These can be used with
low-cost plastic or silica fiber.
One mm diameter plastic fiber
provides the lowest cost solution
for distances under 25 meters.
The lower attenuation of silica
fiber allows data transmission
over longer distance, for a small
difference in cost. These compo-
nents can be used for high speed
data links without the problems
common with copper wire
solutions, at a competitive cost.
The HFBR-15X7 transmitter is a
high power 650 nm LED in a low
cost plastic housing designed to
efficiently couple power into 1
mm diameter plastic optical fiber
and 200
m Hard Clad Silica
(HCS
) fiber. With the recom-
mended drive circuit, the LED
operates at speeds from 1-125
MBd. The HFBR-25X6 is a high
bandwidth analog receiver con-
taining a PIN photodiode and
internal transimpedance amplifier.
With the recommended applica-
tion circuit for 125 MBd
operation, the performance of the
complete data link is specified for
of 0-25 meters with plastic fiber
and 0-100 meters with 200
m
HCS
fiber. A wide variety of
other digitizing circuits can be
combined with the HFBR-0507
Series to optimize performance
and cost at higher and lower data
rates.
HFBR-0507 Series
HFBR-15X7 Transmitters
HFBR-25X6 Receivers
HCS
is a registered trademark of Spectran Corporation.
2
HFBR-0507 Series
125 MBd Data Link
Data link operating conditions
and performance are specified for
the HFBR-15X7 transmitter and
HFBR-25X6 receiver in the
recommended applications
circuits shown in Figure 1. This
circuit has been optimized for 125
MBd operation. The Applications
Engineering Department in the
Agilent Optical Communication
Division is available to assist in
optimizing link performance for
higher or lower speed operation.
Recommended Operating Conditions for the Circuits in Figures 1 and 2.
Parameter
Symbol
Min.
Max.
Unit
Reference
Ambient Temperature
T
A
0
70
C
Supply Voltage
V
CC
+4.75
+5.25
V
Data Input Voltage Low
V
IL
V
CC
-1.89
V
CC
-1.62
V
Data Input Voltage High
V
IH
V
CC
-1.06
V
CC
-0.70
V
Data Output Load
R
L
45
55
Note 1
Signaling Rate
f
S
1
125
MBd
Duty Cycle
D.C.
40
60
%
Note 2
Link Performance:
1-125 MBd, BER
10
-9
, under recommended operating conditions with
recommended transmit and receive application circuits.
Parameter
Symbol
Min.
[3]
Typ.
[4]
Max.
Unit
Condition
Reference
Optical Power Budget, 1 m POF
OPB
POF
11
16
dB
Note 5,6,7
Optical Power Margin,
OPM
POF,20
3
6
dB
Note 5,6,7
20 m Standard POF
Link Distance with
l
20
27
m
Standard 1 mm POF
Optical Power Margin,
OPM
POF,25
3
6
dB
Note 5,6,7
25 m Low Loss POF
Link Distance with Extra
l
25
32
m
Low Loss 1 mm POF
Optical Power Budget, 1 m HCS
OPB
HCS
7
12
dB
Note 5,6,7
Optical Power Margin,
OPM
HCS,100
3
6
dB
Note 5,6,7
100 m HCS
Link Distance with HCS Cable
l
100
125
m
Notes:
1. If the output of U4C in Figure 1, page 4 is transmitted via coaxial cable, terminate with a 50
resistor to V
CC
- 2 V.
2. Run length limited code with maximum run length of 10
s.
3. Minimum link performance is projected based on the worst case specifications of the HFBR-15X7 transmitter, HFBR-25X6 receiver,
and POF cable, and the typical performance of other components (e.g. logic gates, transistors, resistors, capacitors, quantizer,
HCS cable).
4. Typical performance is at 25
C, 125 MBd, and is measured with typical values of all circuit components.
5. Standard cable is HFBR-RXXYYY plastic optical fiber , with a maximum attenuation of 0.24 dB/m at 650 nm and NA = 0.5.
Extra low loss cable is HFBR-EXXYYY plastic optical fiber, with a maximum attenuation of 0.19 dB/m at 650 nm and NA = 0.5.
HCS cable is HFBR-H/VXXYYY glass optical fiber, with a maximum attenuation of 10 dB/km at 650 nm and NA = 0.37.
6. Optical Power Budget is the difference between the transmitter output power and the receiver sensitivity, measured after
1 meter of fiber. The minimum OPB is based on the limits of optical component performance over temperature, process, and
recommended power supply variation.
7. The Optical Power Margin is the available OPB after including the effects of attenuation and modal dispersion for the minimum
link distance: OPM = OPB - (attenuation power loss + modal dispersion power penalty). The minimum OPM is the margin
available for longterm LED LOP degradation and additional fixed passive losses (such as in-line connectors) in addition to the
minimum specified distance.
3
Hard Clad Silica Fiber (200
m HCS) Transmitter Application Circuit:
Performance of
the HFBR-15X7 transmitter in the recommended application circuit (Figure 1) for HCS; 1-125 MBd, 25
C.
Parameter
Symbol
Typical
Unit
Condition
Note
Average Optical Power 200
m HCS
P
avg
-14.6
dBm
50% Duty
Note 1, Fig 3
Cycle
Average Modulated Power 200
m HCS
P
mod
-16.2
dBm
Note 2, Fig 3
Optical Rise Time (10% to 90%)
t
r
3.1
ns
5 MHz
Optical Fall Time (90% to 10%)
t
f
3.4
ns
5 MHz
High Level LED Current (On)
I
F,H
60
mA
Note 3
Low Level LED Current (Off)
I
F,L
6
mA
Note 3
Optical Overshoot - 200
m HCS
30
%
Transmitter Application Circuit
I
CC
130
mA
Figure 1
Current Consumption - 200
m HCS
Notes:
1. Average optical power is measured with an average power meter at 50% duty cycle, after 1 meter of fiber.
2. To allow the LED to switch at high speeds, the recommended drive circuit modulates LED light output between two non-zero power
levels. The modulated (useful) power is the difference between the high and low level of light output power (transmitted) or input
power (received), which can be measured with an average power meter as a function of duty cycle (see Figure 3). Average Modulated
Power is defined as one half the slope of the average power versus duty cycle:
[P
avg
@ 80% duty cycle - P
avg
@ 20% duty cycle]
Average Modulated Power = --------------------------------------------
(2) [0.80 - 0.20]
3. High and low level LED currents refer to the current through the HFBR-15X7 LED. The low level LED "off" current, sometimes
referred to as "hold-on" current, is prebias supplied to the LED during the off state to facilitate fast switching speeds.
Plastic Optical Fiber (1 mm POF) Transmitter Application Circuit:
Performance of the HFBR-15X7 transmitter in the recommended application circuit (Figure 1) for POF; 1-
125 MBd, 25
C.
Parameter
Symbol
Typical
Unit
Condition
Note
Average Optical Power 1 mm POF
P
avg
-9.7
dBm
50% Duty
Note 1, Fig 3
Cycle
Average Modulated Power 1 mm POF
P
mod
-11.3
dBm
Note 2, Fig 3
Optical Rise Time (10% to 90%)
t
r
2.1
ns
5 MHz
Optical Fall Time (90% to 10%)
t
f
2.8
ns
5 MHz
High Level LED Current (On)
I
F,H
19
mA
Note 3
Low Level LED Current (Off)
I
F,L
3
mA
Note 3
Optical Overshoot - 1 mm POF
45
%
Transmitter Application Circuit
I
CC
110
mA
Figure 1
Current Consumption - 1 mm POF
4
Plastic and Hard Clad Silica Optical Fiber Receiver Application Circuit:
Performance
[4]
of the HFBR-25X6 receiver in the recommended application circuit (Figure 1); 1-125 MBd,
25
C unless otherwise stated.
Parameter
Symbol
Typical
Unit
Condition
Note
Data Output Voltage - Low
V
OL
V
CC
-1.7
V
R
L
= 50
Note 5
Data Output Voltage - High
V
OH
V
CC
-0.9
V
R
L
= 50
Note 5
Receiver Sensitivity to Average
P
min
-27.5
dBm
50% eye opening
Note 2
Modulated Optical Power 1 mm POF
Receiver Sensitivity to Average
P
min
-28.5
dBm
50% eye opening
Note 2
Modulated Optical Power 200
m HCS
Receiver Overdrive Level of Average
P
max
-7.5
dBm
50% eye opening
Note 2
Modulated Optical Power 1 mm POF
Receiver Overdrive Level of Average
P
max
-10.5
dBm
50% eye opening
Note 2
Modulated Optical Power 200
m HCS
Receiver Application Circuit Current
I
CC
85
mA
R
L
=
Figure 1
Consumption
Notes:
4. Performance in response to a signal from the HFBR-15X7 transmitter driven with the recommended circuit at 1-125 MBd over 1 meter
of HFBR-R/EXXYYY plastic optical fiber or 1 meter of HFBR-H/VXXYYY hard clad silica optical fiber.
5. Terminated through a 50
resistor to V
CC
- 2 V.
6. If there is no input optical power to the receiver, electrical noise can result in false triggering of the receiver. In typical applications,
data encoding and error detection prevent random triggering from being interpreted as valid data. Refer to Applications Note 1066 for
design guidelines.
5
C1
0.001
C2
0.1
R5
22
Q1
BFQ52
R6
91
R7
91
Q2
BFQ52
C20
10
C19
0.1
T
X
V
EE
9
8
7
6
5
4
3
2
1
J1
Q2 BASE
Q1 BASE
T
X
V
CC
R
X
V
CC
PIN 19 10H116
PIN 18 10H116
R
X
V
EE
NC
L1
CB70-1812
1
2
3
4
5
13
12
10
9
14
7
8
11
6
1
2
3
4
8
5
8
5
1
2
3
4
12
13
5
7
8
9
3
4
17
15
19
18
R24
1K
R22
1K
R18
51
R16
51
C17
0.1
V
BB
V
CC
C10
0.1
R19
51
R17
51
R15
1K
R23
1K
V
BB
C18
0.1
R25
1K
R20
12
R21
62
V
CC
V
BB
3 V
C14
10
TL431
U5
MC10H116FN
C15
0.1
C11
0.1
C16
0.1
C12
0.1
R14
1K
V
BB
3V
C9
.47
R12
4.7
C13
0.1
HFBR-25X6
R13
4.7
U4C
U4A
U4B
U3
R11*
R10
15
C8*
74ACTQ00
U1B
74ACTQ00
U1D
74ACTQ00
U1C
R9*
R8*
HFBR-15X7
C7
0.001
C6
0.1
C5
10
C4
0.001
C3
0.1
Q3
2N3904
V
CC
74ACTQ00
U1A
POF
300
300
1K
43 pF
R8
R9
R11
C8
HCS
82
82
470
120 pF
TOLERANCE
1%
1%
1%
1%
THE VALUES OF R8, R9, R11, AND
C8 ARE DIFFERENT FOR POF AND
HCS DRIVE CIRCUITS.
ALL CAPACITOR VALUES
ARE IN MICRO FARADS,
WITH 10% TOLERANCE
(UNLESS OTHERWISE NOTED).
ALL RESISTANCES ARE IN
OHMS WITH 5% TOLERANCE
(UNLESS OTHERWISE NOTED).
U2
MC10H116FN
MC10H116FN
2
20
+
+
+
10
14
Figure 1. Transmitter and Receiver Application Circuit with +5 V ECL Inputs and Outputs.
5
Figure 2. Recommended Power Supply Filter and +5 V ECL Signal Terminations for
the Transmitter and Receiver Application Circuit of Figure 1.
Figure 4. Typical Optical Power
Budget vs. Data Rate.
Figure 3. Average Modulated Power.
OPTICAL POWER BUDGET dB
10
21
15
9
DATA RATE MBd
90
70
130
150
19
11
110
17
13
30
50
POF
HCS
8 TD
9 T
X
V
EE
7 TD
6 T
X
V
CC
5 R
X
V
CC
4
3 RD
2 RD
82
10 F
0.1 F
4.7 H
0.1 F
1 R
X
V
EE
+5 V ECL
SERIAL DATA
SOURCE
0.1 F
0.1 F
82
120
120
+5 V ECL
SERIAL DATA
RECEIVER
4.7 H
10 F
+
+
+
5 V
82
82
120
120
FIBER-OPTIC
TRANSCEIVER
SHOWN IN
FIGURE 1
4.7 H
AVERAGE POWER W
0
200
100
0
DUTY CYCLE %
20
40
80
100
150
50
60
AVERAGE POWER,
50% DUTY CYCLE
AVERAGE
MODULATED
POWER
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