5
Application Information
The Applications Engineering group is available to assist
you with the technical under standing and design trade-o s
associated with these trans ceivers. You can contact them
through your Avago Technologies sales representative.
The following information is provided to answer some of
the most common questions about the use of these parts.
Transceiver Optical Power Budget versus Link Length
Optical Power Budget (OPB) is the available optical power
for a ber optic link to accommodate ber cable losses plus
losses due to in-line connectors, splices, optical switches,
and to provide margin for link aging and unplanned losses
due to cable plant recon guration or repair.
Figure 4 illustrates the pre dicted OPB associated with the
transceiver speci ed in this data sheet at the Beginning
of Life (BOL). These curves represent the attenuation and
chromatic plus modal dispersion losses associated with
the 62.5/125 μm and 50/125 μm ber cables only. The area
under the curves represents the remaining OPB at any link
length, which is available for overcoming non- ber cable
related losses.
Avago Technologies LED technol ogy has produced
1300 nm LED devices with lower aging characteristics
than normally associated with these technologies in the
industry. The industry conven tion is 1.5 dB aging for 1300
nm LEDs. The Avago Technologies 1300 nm LEDs will
experience less than 1 dB of aging over normal com mer-
cial equip ment mission life periods. Contact your Avago
Technologies sales repre sentative for additional details.
Figure 4 was generated with a Avago Technologies ber
optic link model containing the current industry con-
ventions for ber cable speci cations and the FDDI PMD
and LCF-PMD optical parameters. These parameters are
re ected in the guaranteed performance of the trans-
ceiver speci cations in this data sheet. This same model
has been used extensively in the ANSI and IEEE commit-
tees, including the ANSI X3T9.5 committee, to establish
the optical performance require ments for various ber
optic interface standards. The cable parameters used
come from the ISO/IEC JTC1/SC 25/WG3 Generic Cabling
for Customer Premises per DIS 11801 docu ment and the
EIA/TIA-568-A Commercial Building Telecom munications
Cabling Standard per SP-2840.
Transceiver Signaling Operating Rate Range and
BER Performance
For purposes of de nition, the symbol (Baud) rate, also
called signaling rate, is the reciprocal of the shortest symbol
time. Data rate (bits/sec) is the sym bol rate divided by the
encoding factor used to encode the data (symbols/bit).
When used in FDDI and ATM 100 Mb/s applications the per-
formance of the 1300 nm transceivers is guaranteed over
the signaling rate of 10 MBd to 125 MBd to the full condi-
tions listed in individual product speci cation tables.
Figure 4. Typical Optical Power Budget at BOL versus Fiber Optic Cable
Length.
OPTICAL POWER BUDGET (dB)
0
FIBER OPTIC CABLE LENGTH (km)
0.5 1.5 2.0 2.5
12
10
8
6
4
2
1.0
0.3
HFBR-5903, 62.5/125 µm
HFBR-5903
50/125 µm
CONDITIONS:
1. PRBS 2
7
-1
2. DATA SAMPLED AT CENTER OF DATA
SYMBOL.
3. BER = 10
-6
4. T
A
= +25 ˚C
5. V
CC
= 3.3 V dc
6. INPUT OPTICAL RISE/FALL TIMES = 1.0/
2.1 ns.
-1
-0.5
0
0.5
1
1.5
2
2.5
0
25 50 75 100 125
150 175 200
SIGNAL RATE (MBd)
TRANSCEIVER RELATIVE POWER BUDGET
AT CONSTANT BER (dB)
Figure 5. Transceiver Relative Optical Power Budget at Constant BER vs.
Signaling Rate.
