3
Transmitter Section
The transmitter section includes an 850 nm VCSEL (Vertical
Cavity Surface Emitting Laser) light source and a transmit-
ter driver circuit. The driver circuit maintains a constant
optical power level provided that the data pattern is valid
8B/10B code. Connection to the transmitter is provided
via an LC optical connector.
TX Disable
The HFBR-59L1ALZ accepts a LVTTL transmit disable
control signal input which shuts down the transmitter. A
high signal implements this function while a low signal
allows normal laser operation. In the event of a fault (e.g.,
eye safety circuit activated), cycling this control signal
resets the module. The TX Disable control should be
actuated upon initialization of the module. See Figure 5
for product timing diagrams.
Eye Safety Circuit
For an optical transmitter device to be eye-safe in the
event of a single fault failure, the transmitter will either
maintain normal, eye-safe operation or be disabled. In the
event of an eye safety fault, the VCSEL will be disabled.
Receiver Section
Connection to the receiver is provided via an LC optical
connector. The receiver circuit also includes a Signal
Detect (SD) circuit which provides an LVTTL output logic
low output in the absence of a usable input optical signal
level.
Signal Detect
The Signal Detect (SD) output indicates if the optical input
signal to the receiver does not meet the minimum detect-
able level for Fibre Channel compliant signals. When SD is
low it indicates loss of signal. When SD is high it indicates
normal operation. The Signal Detect thresholds are set
to indicate a denite optical fault has occurred (e.g.,
disconnected or broken ber connection to receiver,
failed transmitter).
Functional Data I/O
Avago Technologies HFBR-59L1ALZ ber-optic transceiver
is designed to accept industry standard dierential signals.
In order to reduce the number of passive components
required on the customer’s board, Avago Technologies has
included the functionality of the transmitter bias resistors
and coupling capacitors within the ber optic module. The
transceiver is compatible with an “ac-coupled” congura-
tion and is internally terminated. Figure 1 depicts the func-
tional diagram of the HFBR-59L1ALZ. Caution should be
taken to account for the proper interconnection between
the supporting Physical Layer integrated circuits and the
HFBR-59L1ALZ. Figure 3 illustrates the recommended
interface circuit.
Reference Designs
Figure 3 depicts a typical application conguration, while
Figure 4 depicts the multisourced power supply lter
circuit design.
Regulatory Compliance
See Table 1 for transceiver Regulatory Compliance perfor-
mance. The overall equipment design will determine the
certication level. The transceiver performance is oered
as a gure of merit to assist the designer.
Electrostatic Discharge (ESD)
There are two conditions in which immunity to ESD
damage is important. Table 1 documents our immunity
to both of these conditions. The rst condition is during
handling of the transceiver prior to attachment to the PCB.
To protect the transceiver, it is important to use normal
ESD handling precautions. These precautions include
using grounded wrist straps, work benches, and oor mats
in ESD controlled areas. The ESD sensitivity of the HFBR-
59L1ALZ is compatible with typical industry production
environments. The second condition is static discharges
to the exterior of the host equipment chassis after instal-
lation. To the extent that the duplex LC optical interface
is exposed to the outside of the host equipment chassis,
it may be subject to system-level ESD requirements. The
ESD performance of the HFBR-59L1ALZ exceeds typical
industry standards.
Immunity
Equipment hosting the HFBR-59L1ALZ modules will be
subjected to radio-frequency electromagnetic elds in
some environments. The transceivers have good immunity
to such elds due to their shielded design.
Electromagnetic Interference (EMI)
Most equipment designs utilizing these high-speed trans-
ceivers from Avago Technologies will be required to meet
the requirements of FCC in the United States, CENELEC
EN55022 (CISPR 22) in Europe and VCCI in Japan. The
metal housing and shielded design of the HFBR-59L1AL
minimize the EMI challenge facing the host equipment
designer.
These transceivers provide superior EMI performance.
This greatly assists the designer in the management of the
overall system EMI performance.
