TXP1XGDS1x
Host Board Termination & Coupling
50Ω line
TD+
CML
INPUTS
50Ω line
50Ω line
TD-
RD+
CML
OUTPUTS
4.7µH coil or
ferrite inductor
50Ω line
RD-
8, 9
+3.3V
+
0.1
22
0.1
ASIC/
SerDes
XFP
+3.3V
+3.3V
R
+3.3V
R
SCL, SDA,
R
Mod_Abs, Mod_NR,
Interrupt, RX_LOS
R: 4.7 to 10kΩ
All caps are in units of µF
Application Notes
Electrical Interface: All signal interfaces are compliant with
the XFP MSA specification. The high speed DATA interface is
differential AC-coupled internally and can be directly connected
to a 3.3V SERDES IC.
be added to the Mod_NR. The Mod_NR output pin is an open
collector and must be pulled to Host_Vcc on the host board.
P_Down/RST: The negative edge of Reset Function signal
initiates a complete module reset.
RX_LOS: The Loss of Signal circuit monitors the level of the
incoming optical signal and generates a logic HIGH when an
insufficient photocurrent is produced.
Module Behavior During P_Down and RST: During execution
of a reset (t_init) or while held in Power Down mode, a module
may be unable to determine the correct value for Mod_NR and
RX_LOS. These outputs as well as all interrupt related flags,
except completion of Reset flag, shall be disregarded by the
host. When the module completes a Reset and is not in Power
Down mode, the module must represent the correct value of
both signals on its outputs before posting a completion of reset
interrupt to the host.
TX_Dis: When theTX Disable pin is at logic HIGH, the transmitter
optical output is disabled. (less than -45dBm).
P_Down: The Power Down Function pin, when held High by
the host, places the module in the standby (Low Power) mode
with a maximum power dissipation of 1.5W. This protects hosts
which are not capable of cooling higher power modules which
may be accidentally inserted.The module’s 2-wire serial interface
and all laser safety functions must be fully functional in this low
power mode. During P_Down, the module shall still support the
completion of reset Interrupt, as well as maintain functionality
of the variable power supply.
At no time shall a module cause spurious assertion of the
Interrupt pin. When a host initially applies power to a module
with the P_Down/RST signal asserted, a module comes up in
power down mode. The module shall only assert the Interrupt
signal pin to inform the host it has completed a reset. The
completion of reset flag shall be the only interrupt source flag
set during power down mode. The host is expected to clear this
interrupt before releasing the module from the power down
mode. The transition from power down mode to normal mode
will trigger a reset of the module and result in a 2nd module reset
and a 2nd reset completion interrupt to the host.
Mod_NR:The Mod_NR is an output pin that when High, indicates
that the module has detected a condition that renders transmitter
and or receiver data invalid, shall consist of logical OR of the
following signals:
• Transmit Signal Conditioner Loss of Lock
• Transmitter Laser Fault
Power Supply and Grounding: The power supply line should
be well-filtered. All 0.1μF power supply bypass capacitors should
be as close to the transceiver module as possible.
• Receiver Signal Conditioner Loss of Lock
Other conditions deemed valuable to the detection of fault may
Oplink Communications, Inc
S0268. Rev.02. 2012-02-10
5
