afct-5710z Avago Technologies, afct-5710z Datasheet - Page 4

• Manufacturer Part Number: afct-5710z
• Description: Families Of Single-mode Small Form Factor Pluggable Sfp Optical Transceivers With Optional Dmi For Gigabit Ethernet 1.25 Gbd
• Manufacturer: Avago Technologies

TX_FAULT
A laser fault or a low VCC condition will activate the
transmitter fault signal, TX_FAULT, and disable the
laser. This signal is an open collector output (pull-up
required on the host board); A low signal indicates
normal laser operation and a high signal indicates a
fault. The TX_FAULT will be latched high when a laser
fault occurs and is cleared by toggling the TX_DISABLE
input or power cycling the transceiver. The TX_FAULT is
not latched for Low VCC. The transmitter fault condition
can also be monitored via the two-wire serial interface
(address A2h, byte 110, bit 2).
Eye Safety Circuit
Under normal operating conditions, the laser power
will be maintained below the eye-safety limit. If the
eye safety limit is exceeded at any time, a laser fault will
occur and the TX_FAULT output will be activated.
Receiver Section
The receiver section for the AFCT-571 Z contains an
InGaAs/InP photo detector and a preamplifier mounted
in an optical subassembly. This optical subassembly is
coupled to a post amplifier/decision circuit on a circuit
board. The design of the optical subassembly provides
better than 12 dB Optical Return Loss (ORL).
Connection to the receiver is provided via a LC optical
connector.
RX_LOS
The receiver section contains a loss of signal (RX_LOS)
circuit to indicate when the optical input signal power
is insufficient for Gigabit Ethernet compliance. A high
signal indicates loss of modulated signal, indicating
link failure such as a broken fiber or a failed transmit-
ter. RX_LOS can be also be monitored via the two-wire
serial (address A2h, byte 110, bit 1).
Figure 4. MSA required power supply filter
4
SFP MODULE
V
V
CC
CC
T
R
0.1 μF
0.1 μF
HOST BOARD
10 μF
1 μH
1 μH
0.1 μF
10 μF
3.3 V
Functional Data I/O
Avago’s AFCT-571 Z transceiver is designed to accept
industry standard differential signals. The transceiv-
er provides an AC-coupled, internally terminated
data interface. Bias resistors and coupling capacitors
have been included within the module to reduce the
number of components required on the customer’s
board. Figure 2 illustrates the recommended interface
circuit.
Digital Diagnostic Interface and Serial Identification
The AFCT-571 Z family complies with the SFF-8074i
specification, which defines the module’s serial identi-
fication protocol to use the 2-wire serial CMOS EEPROM
protocol of the ATMEL AT24C01A or similar. Standard
SFP EEPROM bytes 0-255 are addressed per SFF-8074i
at memory address 0xA0 (A0h).
As an enhancement to the conventional SFP interface
defined in SFF-8074i, the AFCT-5715Z is also compliant
to SFF-8472 (the digital diagnostic interface for SFP).
This enhancement adds digital diagnostic monitoring
to standard SFP functionality, enabling failure predic-
tion, fault isolation, and component monitoring capa-
bilities.
Using the 2-wire serial interface, the AFCT-5715Z
provides real time access to transceiver internal supply
voltage and temperature, transmitter output power,
laser bias current and receiver average input power,
allowing a host to predict system compliance issues.
These five parameters are internally calibrated, per the
MSA. New digital diagnostic information is accessed
per SFF-8472 using EEPROM bytes 0-255 at memory
address 0xA2 (A2h).
The digital diagnostic interface also adds the ability
to disable the transmitter (TX_DISABLE), monitor for
Transmitter Faults (TX_FAULT) and monitor for Receiver
Loss of Signal (RX_LOS).
Contents of the MSA-compliant serial ID memory are
shown in Tables 10 through 14. The SFF-8074i and
SFF-8472 specifications are available from the SFF
Committee at http://www.sffcommittee.org.
Predictive Failure Identification
The diagnostic information allows the host system
to identify potential link problems. Once identified, a
fail-over technique can be used to isolate and replace
suspect devices before system uptime is impacted.