HFCT-5944xxx
Single Mode SFF Transceivers for SONET OC-48/SDH STM-16 Multirate
Operation
(Part of the Avago Technologies METRAK family)
Data Sheet
Description
The HFCT-5944xxx are high performance, cost effective
modules for serial optical data communications ap-
plications that range from 125 Mb/s to 2.7 Gb/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 in-
corporate high performance, reliable, long wavelength
optical devices and proven circuit technology to give
long life and consistent service.
The transmitter section of the HFCT-5944L/AL/G/AG
incorporates a 1300 nm Fabry Perot (FP) laser. The
transmitter in the HFCT-5944TL/ATL/TG/ATG uses a
Distributed Feedback (DFB) Laser packaged in conjunc-
tion 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 ex-
ternal circuitry.
The transceivers are supplied in the new industry stan-
dard 2 x 10 DIP style package with the LC fiber connec-
tor interface and is footprint compatible with SFF Multi
Source Agreement (MSA).
Features
• Multirate operation from 125 Mb/s to 2.7 Gb/s
• HFCT-5944L/AL: Links of 2 km with 9/125 µm single
mode fiber (SMF)
• HFCT-5944TL/ATL: Links of 15 km with 9/125 µm single
mode fiber (SMF)
• Multisourced 2 x 10 package style with LC receptacle
• Single +3.3 V power supply
• Temperature range:
HFCT-5944L/G:
0°C to +70°C
HFCT-5944TL/TG:
0°C to +70°C
HFCT-5944AL/AG: -40°C to +85°C
HFCT-5944ATL/ATG: -20°C to +85°C
• 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-5944L/AL/TL/ATL: metalized nose and EMI
shield
• HFCT-5944G/AG/TG/ATG: no metalization and no EMI
shield
Applications
• SONET/SDH equipment interconnect
• Multirate Client Interface on Metro Gateways and
Edge Switches
Functional Description
Receiver Section
Design
The receiver section for the HFCT-5944xxx 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 il-
lustrated in Figure 1. The coupling capacitors are large
enough to pass the SONET/SDH test pattern at 155 Mb/
s, 622 Mb/s and 2488 Mb/s without significant distor-
tion or performance penalty. For multirate applications
the sensitivity will meet the maximum SONET specifica-
tion for OC48 across all datarates (-19 dBm), also for DC
balanced codes, e.g. 8B/10B. For codes which have a
significantly lower frequency content, 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 de-
signed to bandlimit the preamp output noise and thus
improve the receiver sensitivity.
These components will reduce the sensitivity of the re-
ceiver as the signal bit rate is increased above 2.7 Gb/s.
As an optional feature the device also incorporates a
photodetector bias circuit. The circuit works by provid-
ing 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 resis-
tor (see Application Section).
Noise Immunity
The receiver includes internal circuit components to
filter power supply noise. However under some condi-
tions of EMI and power supply noise, external power
supply filtering may be necessary (see Application Sec-
tion).
The Signal Detect Circuit
The signal detect circuit works by sensing the peak level
of the received signal and comparing this level to a ref-
erence. The SD output is low voltage TTL.
PHOTODETECTOR
BIAS
TRANS-
IMPEDANCE
PRE-
AMPLIFIER
FILTER
AMPLIFIER
DATA OUT
PECL
OUTPUT
BUFFER
DATA OUT
GND
SIGNAL
DETECT
CIRCUIT
TTL
OUTPUT
BUFFER
SD
Figure 1. Receiver Block Diagram
2
Functional Description
Transmitter Section
Design
A schematic diagram for the transmitter is shown in Fig-
ure 2. The HFCT-5944L/AL/G/AG incorporates an FP laser
and the HFCT-5944TL/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 op-
tical output is controlled by a custom IC that detects the
laser output via the monitor photodiode. This IC pro-
vides 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.
FP or
DFB
LASER
DATA
DATA
PECL
INPUT
LASER
MODULATOR
PHOTODIODE
(rear facet monitor)
B
MON
(+)
B
MON
(-)
LASER BIAS
DRIVER
P
MON
(+)
P
MON
(-)
Figure 2. Simplified Transmitter Schematic
LASER BIAS
CONTROL
3
Package
The overall package concept for the device consists of
the following basic elements; two optical subassem-
blies, 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.
In combination witht he metalized nose segment of the
package 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 en-
sure 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 car-
ry the signal pins that exit from the bottom of the trans-
ceiver. 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.
R
X
SUPPLY
*
PHOTO DETECTOR
BIAS
DATA OUT
QUANTIZER IC
DATA OUT
SIGNAL
DETECT
T
X
GROUND
DATA IN
DATA IN
Tx DISABLE
B
MON
(+)
B
MON
(-)
P
MON
(+)
P
MON
(-)
LASER BIAS
MONITORING
LASER DRIVER
AND CONTROL
CIRCUIT
LASER DIODE
OUTPUT POWER
MONITORING
LASER
OPTICAL
SUBASSEMBLY
R
X
GROUND
LC
RECEPTACLE
PIN PHOTODIODE
PREAMPLIFIER
SUBASSEMBLY
T
X
SUPPLY
CASE
* NOSE CLIP PROVIDES CONNECTION TO CHASSIS GROUND FOR BOTH EMI AND THERMAL DISSIPATION.
Figure 3. Block Diagram
4
15.0 ± 0.2
(0.591 ± 0.008)
(
13.59 + 0
- 0.2
0.535 +0
-0.008
)
TOP VIEW
13.59
(0.535)
MAX
6.25
(0.246)
10.8 ± 0.2
(0.425 ± 0.008)
48.5 ± 0.2
(1.91 ± 0.008)
4.06 ± 0.1
(0.16 ± 0.004)
9.8
(0.386)
MAX
3.81 ± 0.15
(0.15 ± 0.006)
9.6 ± 0.2
(0.378 ±0.008)
Ø 1.07 ± 0.1
(0.042 ± 0.004)
19.5 ±0.3
(0.768 ±0.012)
1 ± 0.1
(0.039 ± 0.004)
SIDE VIEW
48.5 ± 0.2
(1.91 ± 0.008)
10.16 ± 0.1
(0.4 ± 0.004)
FRONT VIEW
0.25 ± 0.1
(0.01 ± 0.004)
20 x 0.5 ± 0.2
(0.02 ± 0.008)
1.78 ± 0.1
(0.07 ± 0.004)
1 ± 0.1
(0.039 ± 0.004)
BACK VIEW
G MODULE - NO EMI NOSE SHIELD
9.8
(0.386)
MAX
Ø 1.07 ± 0.1
(0.042 ± 0.004)
19.5 ±0.3
(0.768 ±0.012)
1 ± 0.1
(0.039 ± 0.004)
SIDE VIEW
3.81 ± 0.1
(0.15 ± 0.004)
0.25 ± 0.1
(0.01 ± 0.004)
20 x 0.5 ± 0.2
(0.02 ± 0.008)
1.78 ± 0.1
(0.07 ± 0.004)
20 x 0.25 ± 0.1
(PIN THICKNESS)
(0.01 ± 0.004)
NOTE: END OF PINS
CHAMFERED
BOTTOM VIEW
DIMENSIONS IN MILLIMETERS (INCHES)
DIMENSIONS SHOWN ARE NOMINAL. ALL DIMENSIONS MEET THE MAXIMUM PACKAGE OUTLINE DRAWING IN THE SFF MSA.
Figure 4. HFCT-5944xxx Package Outline Drawing
5
京公网安备 11010802033920号
EEWORLD
