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9.3
Gigabit Ethernet
Table 8 Ethernet Signal Descriptions
Signal
Pin #
Description
I/O
PU/PD Comment
G
GBE_MDI0-
12
10
Media Dependent Interface (MDI) differential pair 0. The MDI can
operate in 1000, 100, and 10Mbit/sec modes.
This signal pair is used for all modes.
I/O Analog
Twisted pair signals for external
transformer.
G
GBE_MDI1-
11
9
Media Dependent Interface (MDI) differential pair 1. The MDI can
operate in 1000, 100, and 10Mbit/sec modes.
This signal pair is used for all modes.
I/O Analog
Twisted pair signals for external
transformer.
G
GBE_MDI2-
6
4
Media Dependent Interface (MDI) differential pair 2. The MDI can
operate in 1000, 100, and 10Mbit/sec modes.
This signal pair is only used for 1000Mbit/sec Gigabit Ethernet mode.
I/O Analog
Twisted pair signals for external
transformer.
G
GBE_MDI3-
5
3
Media Dependent Interface (MDI) differential pair 3. The MDI can
operate in 1000, 100, and 10Mbit/sec modes.
This signal pair is only used for 1000Mbit/sec Gigabit Ethernet mode.
I/O Analog
Twisted pair signals for external
transformer.
GBE_CTREF
15
Reference voltage for carrier board Ethernet channel 0 magnetics center
tap. The reference voltage is determined by the requirements of the
module's PHY and may be as low as 0V and as high as 3.3V.
The reference voltage output should be current limited on the module. In
a case in which the reference is shorted to ground, the current must be
limited to 250mA or less.
REF
Not Supported
GBE_LINK#
13
Ethernet controller 0 link indicator, active low.
O 3.3V PP PD 1k
GBE0_LINK# is a bootstrap signal
(see note below)
GBE_LINK100#
7
Ethernet controller 0 100Mbit/sec link indicator, active low.
O 3.3V PP
PU 4k99
2,5VSB
Not Supported. Internally
connected to GBE_ACT#.
GBE0_LINK100# is a bootstrap
signal (see note below)
GBE_LINK1000#
8
Ethernet controller 0 1000Mbit/sec link indicator, active low.
O 3.3V PP PD 1k
Not Supported. Internally
connected to GBE_LINK#.
GBE0_LINK1000# is a bootstrap
signal (see note below)
GBE_ACT#
14
Ethernet controller 0 activity indicator, active low.
O 3.3V PP
PU 4k99
2,5VSB
GBE0_ACT# is a bootstrap signal
(see note below)
Note
The theoretical maximum performance of 1 Gbps Ethernet is limited to 470 Mbps (total for Tx and Rx) due to internal bus throughput limitations.
The actual measured performance in optimized environment is up to 400 Mbps. For more information, consult Freescale’s Errata ERR004512.
Some signals have special functionality during the reset process. They may bootstrap some basic important functions of the module.
For more information refer to section 9.21 of this user’s guide.
