Transmitter Section
TX_FAULT
The transmitter section includes a 1310 nm Fabry-Perot
laser and a transmitter driver circuit. The driver circuit
A laser fault or a low V condition will activate the trans-
mitter fault signal, TX_FAULT, and disable the laser. This
CC
maintains a constant optical power level provided that signal is an open collector output (pull-up required on
the data pattern is valid for NRZ code. Connection to the
transmitter is provided via a LC optical connector.
the host board); A low signal indicates normal laser op-
eration 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
The transmitter has full IEC 825 and CDRH Class 1 eye
safety.
Low V . The transmitter fault condition can also be
TX_DISABLE
CC
monitored via the two-wire serial interface (address A2,
byte 110, bit 2). By default, TX_FAULT is set to trigger on
hardware faults only.
The transmitter output can be disabled by asserting pin
3, TX_DISABLE. A high signal asserts this function while
a low signal allows normal laser operation. The transmit-
ter output can also be disabled and monitored via the
2-wire serial interface. In the event of a transceiver fault,
such as the activation of the eye safety circuit, toggling
of the TX_DISABLE will reset the transmitter, as depicted
in Figure 2.
1 µH
1 µH
3.3 V
10 µF
0.1 µF
3.3 V
V
,T
CC
SFP MODULE
4.7 K to 10 KΩ
0.1 µF
4.7 K to 10 KΩ
Tx_DISABLE
Tx_FAULT
Tx_FAULT
VREFR
0.01 µF
0.01 µF
TD+
50 Ω
50 Ω
VREFR
SO+
SO–
LASER DRIVER
100 Ω
TX[0:9]
& SAFETY
TD–
TX GND
CIRCUITRY
TBC
TBC
EWRAP
EWRAP
V
,R
CC
4.7 K to 10 KΩ
50 Ω
V
,R
CC
0.1
µF
PROTOCOL
IC
10 µF
50 Ω
RX[0:9]
0.01 µF
0.01 µF
RD+
SI+
RBC
Rx_RATE
RBC
Rx_RATE
AMPLIFICATION
&
QUANTIZATION
100
SI–
Ω
RD–
50 Ω
REFCLK
Rx_LOS
RX GND
Rx_LOS
50 Ω
,R
V
MOD_DEF2
MOD_DEF1
MOD_DEF0
CC
GPIO(X)
GPIO(X)
GP14
EEPROM
REFCLK
4.7 K to 4.7 K to
10 KΩ 10 KΩ
4.7 K to
10 KΩ
3.3 V
Figure 2. Typical Application Configuration
3