3
3) Mod-Def 0,1,2. These are the module definition pins. They should be pulled up with a 4.7k –
10k
resistor on the host board. The pull-up voltage shall be VccT or VccR.
Mod-Def 0 is grounded by the module to indicate that the module is present Mod-Def 1 is the clock
line of two wire serial interface for serial ID Mod-Def 2 is the data line of two wire serial interface for
serial ID.
4) LOS(Loss of Signal) is an open collector/drain output, which should be pulled up with a 4.7k –
10k
resistor. When high, this output indicates the received optical power is below the worst-case
receiver sensitivity (as defined by the standard in use). Low indicates normal operation. In the low
state, the output will be pulled to < 0.8V.
5) VeeR and VeeT may be internally connected within the SFP module.
6) Rx_Data-/+: These are the differential receiver outputs. They are AC coupled 100
differential
lines which should be terminated with 100
(differential) at the user SERDES. The AC coupling is
done inside the module and is thus not required on the host board. The voltage swing on these lines
will be between 600 and 800mV differential when properly terminated.
7) VccR and VccT are the receiver and transmitter power supplies. They are defined as 3.3V±5% at
the SFP connector pin. Maximum supply current is 300 mA. Recommended host board power supply
filtering is shown below. Inductors with DC resistance of less than 1
should be used in order to
maintain the required voltage at the SFP input pin with 3.3V supply voltage. When the recommended
supply filtering network is used, hot plugging of the SFP transceiver module will result in an inrush
current of no more than 30 mA greater than the steady state value. VccR and VccT may be internally
connected within the SFP transceiver module.
8) Tx_Data-/+: These are the differential transmitter inputs. They are AC-coupled, differential lines with
100
differential termination inside the module. The AC coupling is done inside the module and is thus
not required on the host board. The inputs will accept differential swings of 200 – 1660 mV, though it is
recommended that values between 500 and 1200 mV differential be used for best EMI performance.
Figure 1. Recommended Host Board Supply Filtering Network
Application Circuit