AFBR-5710Z Datasheet, PDF (5/20 Pages) AVAGO TECHNOLOGIES LIMITED – Families of Multi-Mode Small Form Factor Pluggable (SFP) Optical Transceivers

As an enhancement to the conventional SFP interface
defined in SFF-8074i, the AFBR-5715Z family is compliant
to SFF-8472 (digital diagnostic interface for optical trans-
ceivers). This new digital diagnostic information is stored
in bytes 0-255 at memory address 0xA2.Using the 2-wire
serial interface defined in the MSA, the AFBR-5715Z
provides real time temperature, supply voltage, laser
bias current, laser average output power and received
input power. These parameters are internally calibrated,
per the MSA.
The digital diagnostic interface also adds the ability to
disable the transmitter (TX_DISABLE), monitor for Trans-
mitter Faults (TX_FAULT), and monitor for Receiver Loss
of Signal (RX_LOS).
The new diagnostic information provides the oppor-
tunity for Predictive Failure Identification, Compliance
Prediction, Fault Isolation and Component Monitoring.
Predictive Failure Identification
The predictive failure feature allows a host to identify
potential link problems before system performance is
impacted. Prior identification of link problems enables
a host to service an application via “fail over” to a redun-
dant link or replace a suspect device, maintaining system
uptime in the process. For applications where ultra-high
system uptime is required, a digital SFP provides a means
to monitor two real-time laser metrics associated with ob-
serving laser degradation and predicting failure: average
laser bias current (Tx_Bias) and average laser optical power
(Tx_Power).
Compliance Prediction
Compliance prediction is the ability to determine if an
optical transceiver is operating within its operating and
environmental requirements. AFBR-5715Z devices provide
real-time access to transceiver internal supply voltage
and temperature, allowing a host to identify potential
component compliance issues. Received optical power is
also available to assess compliance of a cable plant and
remote transmitter. When operating out of requirements,
the link cannot guarantee error free transmission.
Fault Isolation
The fault isolation feature allows a host to quickly pin-
point the location of a link failure, minimizing downtime.
For optical links, the ability to identify a fault at a local
device, remote device or cable plant is crucial to speeding
service of an installation. AFBR-5715Z real-time monitors
of Tx_Bias, Tx_Power, Vcc, Temperature and Rx_Power
can be used to assess local transceiver current operating
conditions. In addition, status flags Tx_Disable and Rx Loss
of Signal (LOS) are mirrored in memory and available via
the two-wire serial interface.
Component Monitoring
Component evaluation is a more casual use of the AFBR-
5715Z real-time monitors of Tx_Bias, Tx_Power, Vcc, Tem-
perature and Rx_Power. Potential uses are as debugging
aids for system installation and design, and transceiver
parametric evaluation for factory or field qualification.
For example, temperature per module can be observed in
high density applications to facilitate thermal evaluation
of blades, PCI cards and systems.
Required Host Board Components
The MSA power supply noise rejection filter is required on
the host PCB to meet data sheet performance. The MSA
filter incorporates an inductor which should be rated 400
mADC and 1 Ω series resistance or better. It should not
be replaced with a ferrite. The required filter is illustrated
in Figure 4.
The MSA also specifies that 4.7 K to 10 KΩ pull-up resis-
tors for TX_FAULT, LOS, and MOD_DEF0,1,2 are required
on the host PCB.
1 µH
V_CCT
0.1 µF
1 µH
V_CCR
3.3 V
0.1 µF
10 µF
0.1 µF
10 µF
SFP MODULE
HOST BOARD
Figure 4. MSA required power supply filter.
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