AFBR-53D3EZ Avago Technologies US Inc., AFBR-53D3EZ Datasheet - Page 4

• Manufacturer Part Number: AFBR-53D3EZ
• Description: TXRX OPTICAL 5V VCSEL FC 1X9
• Manufacturer: Avago Technologies US Inc.

Specifications of AFBR-53D3EZ

• Applications: Ethernet
• Wavelength: 850nm
• Voltage - Supply: 4.75 V ~ 5.25 V
• Connector Type: SC
• Mounting Type: Through Hole
• Supply Voltage: 5V
• Wavelength Typ: 850nm
• Peak Reflow Compatible (260 C): Yes
• Leaded Process Compatible: Yes
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Data Rate: -
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant, Lead free / RoHS Compliant

APPLICATION SUPPORT
Optical Power Budget and Link Penalties
The worst-case Optical Power Budget (OPB) in dB for a
fiberoptic link is determined by the difference between
the minimum transmitter output optical power (dBm
avg.) and the lowest receiver sensitivity (dBm avg.). This
OPB provides the necessary optical signal range to
establish a working fiber-optic link. The OPB is allocated
for the fiber-optic cable length and the corresponding
link penalties. For proper link performance, all penalties
that affect the link performance must be accounted for
within the link optical power budget.
Data Line Interconnections
Avago Technologies’ AFBR-53D3 fiberoptic transceiver
is designed to directly couple to +5 V PECL signals. The
transmitter inputs are internally dc-coupled to the laser
driver circuit from the transmitter input pins (pins 7, 8).
There is no internal, capacitivelycoupled 50 Ohm
termination resistance within the transmitter input
section. The transmitter driver circuit for the laser light
source is a dc-coupled circuit. This circuit regulates the
output optical power. The regulated light output will
maintain a constant output optical power provided the
data pattern is reasonably balanced in duty factor. If the
data duty factor has long, continuous state times (low
or high data duty factor), then the output optical power
will gradually change its average output optical power
level to its preset value.
As for the receiver section, it is internally AC-coupled
between the preamplifier and the postamplifier stages.
The actual Data and Data-bar outputs of the
postamplifier are DC-coupled to their respective output
pins (pins 2, 3). Signal Detect is a single-ended, +5 V
PECL output signal that is dc-coupled to pin 4 of the
module. Signal Detect should not be accoupled
externally to the follow-on circuits because of its
infrequent state changes.
Caution should be taken to account for the proper
interconnection between the supporting Physical Layer
integrated circuits and this AFBR-53D3 transceiver.
Figure 3 illustrates a recommended interface circuit for
interconnecting to a +5 V dc PECL fiber-optic transceiver.
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Some fiber-optic transceiver suppliers’ modules include
internal capacitors, with or without 50 Ω termination,
to couple their Data and Data-bar lines to the I/O pins
of their module. When designing to use these type of
transceivers along with Avago Technologies
transceivers, it is important that the interface circuit can
accommodate either internal or external capacitive
coupling with 50 Ω termination components for proper
operation of both transceiver designs. The internal dc-
coupled design of the AFBR-53D3 I/O connections was
done to provide the designer with the most flexibility
for interfacing to various types of circuits.
Eye Safety Circuit
For an optical transmitter device to be eye-safe in the
event of a single fault failure, the transmitter must either
maintain normal, eyesafe operation or be disabled. In
the AFBR-53D3 there are three key elements to the laser
driver safety circuitry: a monitor diode, a window
detector circuit and direct control of the laser bias. The
window detection circuit monitors the average optical
power using the monitor diode. If a fault occurs such
that the transmitter dc regulation circuit cannot maintain
the preset bias conditions for the laser emitter within
±20%, the transmitter will automatically be disabled.
Once this has occurred, only an electrical power reset
will allow an attempted turn-on of the transmitter.
Signal Detect
The Signal Detect circuit provides a deasserted output
signal that implies the link is open or the transmitter is
OFF. The Signal Detect threshold is set to transition from
a high to low state between the minimum receiver input
optional power and -30 dBm avg. input optical power
indicating a definite optical fault (e.g. unplugged
connector for the receiver or transmitter, broken fiber,
or failed far-end transmitter or data source). A Signal
Detect indicating a working link is functional when
receiving encoded 8B/l0B characters. The Signal Detect
does not detect receiver data error or error-rate. Data
errors are determined by Signal processing following
the transceiver.