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IXF1104 4-Port Gigabit Ethernet Media Access Controller
Datasheet 104
Document Number: 278757
Revision Number: 009
Revision Date: 27-Oct-2005
speed SerDes and are capable of operating in either an AC- or DC-coupled environment. AC
coupling is recommended for this interface to ensure that the correct input bias current is supplied
at the receiver.
The SerDes receive interface receives serialized data at 1.25 GHz. The interface is differential with
two signals for the receive operation. The equalizer receives a differential signal that is equalized
for the assumed media channel. The SerDes transmit and receive interfaces are designed to operate
within a 100 Ω differential environment and all terminations are included on the device. The
SerDes is capable of operating in either AC- or DC-coupled environments.
5.6.2.1 Transmitter Operational Overview
The transmit section of the IXF1104 MAC has to serialize the Ten Bit Interface (TBI) data from the
IXF1104 MAC MAC section and outputs this data at 1.25 GHz differential signal levels. The
1.25 GHz differential SerDes signals are compliant with the Small Form Factor Pluggable (SFP)
Multi-Source Agreement (MSA).
The transmitter section takes the contents of the data register within the MAC and synchronously
transfers the data out, ten bits at a time – Least Significant Bit (LSB) first, followed by the next
Most Significant Bit (MSB). When these ten bits have been serialized and transmitted, the next
word of 10-bit data from the MAC is ready to be serialized for transmission.
The data is transmitted by the high-speed current mode differential SerDes output stage using an
internal 1.25 GHz clock generated from the 125 MHz clock input.
5.6.2.2 Transmitter Programmable Driver-Power Levels
The IXF1104 MAC SerDes core has programmable transmitter power levels to enhance usability
in any given application.The SerDes Registers are programmable to allow adjustment of the
transmit core driver output power. When driving a 100 Ω differential terminated network, these
output power settings effectively establish the differential voltage swings at the driver output.
The “TX Driver Power Level Ports 0 - 3 ($0x784)" allows the selection of four discrete power
settings. The selected power setting of these inputs is applied to each of the transmit core drivers on
a per-port basis. Table 29 “SerDes Driver TX Power Levels” lists the normalized power settings of
the transmit drivers as a function of the Driver Power Control inputs. The normalized current
setting is 10 mA, which corresponds to the normalized power setting of 1.0. This is the default
setting of the IXF1104 MAC SerDes interface. Other values listed in the Normalized Driver Power
Setting column are multiples of 10 mA. For example, with inputs at 1110, the driver power is the
following:
.5 x 10 mA = 5 mA.
Table 29. SerDes Driver TX Power Levels
DRVPWRx[3] DRVPWRx[2] DRVPWRx[1] DRVPWRx[0]
Normalized
Driver Power
Setting
Driver Power
0 0 1 1 1.33 13.3 mA
NOTE: All other values are reserved.