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Электронный компонент: HFCT-5942AL

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Agilent HFCT-5942xxx Single Mode Laser
Small Form Factor Transceivers for
ATM, SONET OC-48/SDH STM-16
Data Sheet
Description
The HFCT-5942xxx are high
performance, cost effective
modules for serial optical data
communications applications at
2488 Mb/s. They are designed to
provide SONET/SDH compliant
links at 2488 Mb/s for both short
and intermediate reach links.
The modules are designed for
single mode fiber and operate at a
nominal wavelength of 1300 nm.
They incorporate high
performance, reliable, long
wavelength optical devices and
proven circuit technology to give
long life and consistent service.
The transmitter section of the
HFCT-5942L/AL/G/AG
incorporates a 1300 nm Fabry
Perot (FP) laser. The transmitter
in the HFCT-5942TL/ATL/TG/
ATG uses a Distributed Feedback
(DFB) Laser packaged in
conjunction with an optical
isolator for excellent back
reflection performance. The
transmitter has full IEC 825 and
CDRH Class 1 eye safety.
For each device the receiver
section uses an MOVPE grown
planar SEDET PIN photodetector
for low dark current and excellent
responsivity.
A positive ECL logic interface
simplifies interface to external
circuitry.
The transceivers are supplied in
the new industry standard 2 x 10
DIP style package with the LC
fiber connector interface and is
footprint compatible with SFF
Multi Source Agreement (MSA).
Features
HFCT-5942L/AL:
Links of 2 km with 9/125 m
single mode fiber (SMF)
HFCT-5942TL/ATL:
Links of 15 km with 9/125 m
single mode fiber (SMF)
Multisourced 2 x 10 package style
with LC receptacle
Single +3.3 V power supply
Temperature range:
HFCT-5942L/G:
0C to +70C
HFCT-5942TL/TG:
0C to +70C
HFCT-5942AL/AG: -40C to +85C
HFCT-5942ATL/ATG:
-20C to +85C
Wave solder and aqueous wash
process compatible
Manufactured in an ISO9002
certified facility
Fully Class 1 CDRH/IEC 825
compliant
Compliant with ITU-T G.957
STM-16, I-16 and S-16.1 Optical
Interfaces
HFCT-5942L/AL/TL/ATL:
with EMI nose shield
HFCT-5942G/AG/TG/ATG:
without EMI nose shield
Applications
SONET/SDH equipment
interconnect, OC-48/SDH STM-16
rate
Short and intermediate reach
ATM/SONET links
2
Functional Description
Receiver Section
Design
The receiver section for the
HFCT-5942xxx contains an
InGaAs/InP photo detector and a
preamplifier mounted in an
optical subassembly. This optical
subassembly is coupled to a
postamp/decision circuit on a
circuit board. The design of the
optical assembly is such that it
provides better than 27 dB
Optical Return Loss (ORL).
The postamplifier is ac coupled to
the preamplifier as illustrated in
Figure 1. The coupling capacitors
are large enough to pass the
SONET/SDH test pattern at
2488 Mb/s without significant
distortion or performance
penalty. If a lower signal rate, or
a code which has significantly
more low frequency content is
used, sensitivity, jitter and pulse
distortion could be degraded.
Figure 1 also shows a filter
function which limits the
bandwidth of the preamp output
signal. The filter is designed to
bandlimit the preamp output
noise and thus improve the
receiver sensitivity.
These components will reduce
the sensitivity of the receiver as
the signal bit rate is increased
above 2488 Mb/s.
As an optional feature the device
also incorporates a photodetector
bias circuit. The circuit works by
providing a mirrored output of
the bias current within the
photodiode. This output must be
connected to V
CC
and can be
monitored by connecting through
a series resistor (see Application
Section).
Figure 1. Receiver Block Diagram
Noise Immunity
The receiver includes internal
circuit components to filter
power supply noise. However
under some conditions of EMI
and power supply noise, external
power supply filtering may be
necessary (see Application
Section).
The Signal Detect Circuit
The signal detect circuit works
by sensing the peak level of the
received signal and comparing
this level to a reference. The SD
output is low voltage TTL.
TRANS-
IMPEDANCE
PRE-
AMPLIFIER
FILTER
GND
AMPLIFIER
PECL
OUTPUT
BUFFER
TTL
OUTPUT
BUFFER
DATA OUT
SIGNAL
DETECT
CIRCUIT
SD
DATA OUT
PHOTODETECTOR
BIAS
3
Figure 2. Simplified Transmitter Schematic
Functional Description
Transmitter Section
Design
A schematic diagram for the
transmitter is shown in Figure 2.
The HFCT-5942L/AL/G/AG
incorporates an FP laser and the
HFCT-5942TL/TG/ATL/ATG uses
a DFB packaged in conjunction
with an optical isolator. Both
packages have been designed to
be compliant with IEC 825 eye
safety requirements under any
single fault condition and CDRH
under normal operating
conditions. The optical output is
controlled by a custom IC that
detects the laser output via the
monitor photodiode. This IC
provides both dc and ac current
drive to the laser to ensure
correct modulation, eye diagram
and extinction ratio over
temperature, supply voltage and
operating life.
The transmitters also include
monitor circuitry for both the
laser diode bias current and laser
diode optical power.
DATA
DATA
PECL
INPUT
LASER
MODULATOR
FP or
DFB
LASER
LASER BIAS
DRIVER
LASER BIAS
CONTROL
PHOTODIODE
(rear facet monitor)
B
MON
(+)
B
MON
(-)
P
MON
(+)
P
MON
(-)
4
Package
The overall package concept for
the device consists of the
following basic elements; two
optical subassemblies, two
electrical subassemblies and the
housing as illustrated in the block
diagram in Figure 3.
The package outline drawing and
pin out are shown in Figures 4
and 5. The details of this package
outline and pin out are compliant
with the multisource definition
of the 2 x 10 DIP.
A metallic nose clip provides
connection to chassis ground for
both EMI and thermal dissipation.
The electrical subassemblies
consist of high volume
multilayer printed circuit boards
on which the IC and various
surface-mounted passive circuit
elements are attached.
The receiver electrical
subassembly includes an internal
shield for the electrical and
optical subassembly to ensure
high immunity to external EMI
fields.
The optical subassemblies are
each attached to their respective
transmit or receive electrical
subassemblies. These two units
are then fitted within the outer
housing of the transceiver that is
molded of filled nonconductive
plastic to provide mechanical
strength. The housing is then
encased with a metal EMI
protective shield. The case is
signal ground and we recommend
soldering the four ground tabs to
host card signal ground.
The pcb's for the two electrical
subassemblies both carry the
signal pins that exit from the
bottom of the transceiver. The
solder posts are fastened into the
molding of the device and are
designed to provide the
mechanical strength required to
withstand the loads imposed on
the transceiver by mating with
the LC connectored fiber cables.
Although they are not connected
electrically to the transceiver, it
is recommended to connect them
to chassis ground.
Figure 3. Block Diagram
DATA OUT
SIGNAL
DETECT
DATA IN
DATA IN
Tx DISABLE
B
MON
(+)
B
MON
(-)
P
MON
(+)
P
MON
(-)
QUANTIZER IC
LASER DRIVER
AND CONTROL
CIRCUIT
PIN PHOTODIODE
PREAMPLIFIER
SUBASSEMBLY
LASER
OPTICAL
SUBASSEMBLY
DATA OUT
LC
RECEPTACLE
R
X
SUPPLY
T
X
SUPPLY
R
X
GROUND
T
X
GROUND
PHOTO DETECTOR
BIAS
LASER BIAS
MONITORING
LASER DIODE
OUTPUT POWER
MONITORING
CASE
*
* NOSE CLIP PROVIDES CONNECTION TO CHASSIS GROUND FOR BOTH EMI AND THERMAL DISSIPATION.
5
Figure 4. HFCT-5942xxx Package Outline Drawing
TOP VIEW
13.59
(0.535)
MAX
13.59
0.535
+ 0
- 0.2
+0
-0.008
( )
15.0 0.2
(0.591 0.008)
6.25
(0.246)
10.16
(0.4)
9.6 0.2
(0.378 0.008)
1.07
(0.042)
1
(0.039)
1.78
(0.07)
20 x 0.5
(0.02)
0.25
(0.01)
3.81
(0.15)
9.8
(0.386)
MAX
48.2
(1.898)
FRONT VIEW
SIDE VIEW
BACK VIEW
19.5 0.3
(0.768 0.012)
1
(0.039)
10.8 0.2
(0.425 0.008)
1.07
(0.042)
1
(0.039)
1.78
(0.07)
20 x 0.5
(0.02)
0.25
(0.01)
3.81
(0.15)
9.8
(0.386)
MAX
48.2
(1.898)
SIDE VIEW
19.5 0.3
(0.768 0.012)
G MODULE - NO EMI NOSE SHIELD
20 x 0.25
(0.01)
BOTTOM VIEW
(PIN THICKNESS)
NOTE: END OF PINS
CHAMFERED
DIMENSIONS IN MILLIMETERS (INCHES)
DIMENSIONS SHOWN ARE NOMINAL. ALL DIMENSIONS MEET THE MAXIMUM PACKAGE OUTLINE DRAWING IN THE SFF MSA.