11
Notes:
1. This is the maximum voltage that can
be applied across the Differential
Transmitter Data Inputs to prevent
damage to the input ESD protection
circuit.
2. The outputs are terminated with 50
connected to V
CC
- 2 V.
3. The specified signaling rate of
10 MBd to 125 MBd guarantees
operation of the transmitter and
receiver link to the full conditions
listed in the FDDI Physical Layer
Medium Dependent standard.
Specifically, the link bit-error-ratio
will be equal to or better than 2.5 x
10
-10
for any valid FDDI pattern. The
transmitter section of the link is
capable of dc to 125 MBd. The
receiver is internally ac-coupled
which limits the lower signaling rate
to 10 MBd. For purposes of
definition, the symbol rate (Baud),
also called signaling rate, fs, is the
reciprocal of the symbol time. Data
rate (bits/sec) is the symbol rate
divided by the encoding factor used
to encode the data (symbols/bit).
4. The power supply current needed to
operate the transmitter is provided to
differential ECL circuitry. This
circuitry maintains a nearly constant
current flow from the power supply.
Constant current operation helps to
prevent unwanted electrical noise
from being generated and conducted
or emitted to neighboring circuitry.
5. This value is measured with an output
load R
L
= 10 k
.
6. This value is measured with the out-
puts terminated into 50
connected
to V
CC
- 2 V and an Input Optical
Power level of -14 dBm average.
7. The power dissipation value is the
power dissipated in the transmitter
and receiver itself. Power dissipation
is calculated as the sum of the
products of supply voltage and
currents, minus the sum of the
products of the output voltages and
currents.
8. This value is measured with respect to
V
CC
with the output terminated into
50
connected to V
CC
- 2 V.
9. The output rise and fall times are
measured between 20% and 80%
levels with the output connected to
V
CC
- 2 V through 50
.
10. Duty Cycle Distortion contributed by
the receiver is measured at the 50%
threshold using an IDLE Line State,
125 MBd (62.5 MHz square-wave),
input signal. The input optical power
level is -20 dBm average. See
Application Information–Data Link
Jitter Section for further information.
11. Data Dependent Jitter contributed by
the receiver is specified with the
FDDI DDJ test pattern described in
the FDDI PMD Annex A.5. The input
optical power level is -20 dBm
average. See Application
Information–Data Link Jitter Section
for further information.
12. Random Jitter contributed by the
receiver is specified with an IDLE
Line State, 125 MBd (62.5 MHz
square-wave), input signal. The input
optical power level is at the maxi-
mum of “P
IN Min.
(W).” See Applica-
tion Information–Data Link Jitter
Section for further information.
13. These optical power values are
measured with the following
conditions:
The Beginning of Life (BOL) to the
End of Life (EOL) optical power
degradation is typically 1.5 dB per
the industry convention for long
wavelength LEDs. The actual
degradation observed in Hewlett-
Packard’s 1300 nm LED products
is < 1dB, as specified in this data
sheet.
Over the specified operating
voltage and temperature ranges.
With HALT Line State, (12.5 MHz
square-wave), input signal.
At the end of one meter of noted
optical fiber with cladding modes
removed.
The average power value can be
converted to a peak power value by
adding 3 dB. Higher output optical
power transmitters are available on
special request.
14. The Extinction Ratio is a measure of
the modulation depth of the optical
signal. The data “0” output optical
power is compared to the data “1”
peak output optical power and
expressed as a percentage. With the
transmitter driven by a HALT Line
State (12.5 MHz square-wave) signal,
the average optical power is
measured. The data “1” peak power is
then calculated by adding 3 dB to the
measured average optical power. The
data “0” output optical power is
found by measuring the optical power
when the transmitter is driven by a
logic “0” input. The extinction ratio is
the ratio of the optical power at the
“0” level compared to the optical
power at the “1” level expressed as a
percentage or in decibels.
15. The transmitter provides compliance
with the need for Transmit_Disable
commands from the FDDI SMT layer
by providing an Output Optical
Power level of <-45 dBm average in
response to a logic “0” input. This
specification applies to either 62.5/
125
μ
m or 50/125
μ
m fiber cables.
16. This parameter complies with the
FDDI PMD requirements for the
tradeoffs between center wavelength,
spectral width, and rise/fall times
shown in Figure 9.
17. This parameter complies with the
optical pulse envelope from the FDDI
PMD shown in Figure 10. The optical
rise and fall times are measured from
10% to 90% when the transmitter is
driven by the FDDI HALT Line State
(12.5 MHz square-wave) input signal.
18. Duty Cycle Distortion contributed by
the transmitter is measured at a 50%
threshold using an IDLE Line State,
125 MBd (62.5 MHz square-wave),
input signal. See Application
Information–Data Link Jitter Per-
formance Section of this data sheet
for further details.
19. Data Dependent Jitter contributed by
the transmitter is specified with the
FDDI test pattern described in FDDI
PMD Annex A.5. See Application
Information–Data Link Jitter
Performance Section of this data
sheet for further details.
20. Random Jitter contributed by the
transmitter is specified with an IDLE
Line State, 125 MBd (62.5 MHz
square-wave), input signal. See
Application Information–Data Link
Jitter Performance Section of this
data sheet for further details.
21. This specification is intended to
indicate the performance of the
receiver when Input Optical Power
signal characteristics are present per
the following definitions. The Input
Optical Power dynamic range from
the minimum level (with a window
time-width) to the maximum level is
the range over which the receiver is
guaranteed to provide output data
with a Bit-Error-Ratio (BER) better
than or equal to 2.5 x 10
-10
.
At the Beginning of Life (BOL).
Over the specified operating
voltage and temperature ranges.
Input symbol pattern is the FDDI
test pattern defined in FDDI PMD
Annex A.5 with 4B/5B NRZI
encoded data that contains a duty-
cycle base-line wander effect of