PCI Express
Table 61. Differential Transmitter (TX) Output Specifications (continued)
Symbol
Parameter
Min Nominal Max Units
Comments
I
TX Short Circuit
Current Limit
—
—
90
—
mA The total current the Transmitter can provide when
shorted to its ground
TX-SHORT
T
Minimum time
spent in
Electrical Idle
50
—
UI Minimum time a Transmitter must be in Electrical
Idle Utilized by the Receiver to start looking for an
Electrical Idle Exit after successfully receiving an
Electrical Idle ordered set
TX-IDLE-MIN
T
Maximum time to
transition to a
valid Electrical
idle aftersending
an Electrical Idle
ordered set
—
—
20
20
UI After sending an Electrical Idle ordered set, the
Transmitter must meet all Electrical Idle
TX-IDLE-SET-TO-IDLE
Specifications within this time. This is considered a
debounce time for the Transmitter to meet Electrical
Idle after transitioning from L0.
T
Maximum time to
transition to valid
TX specifications
after leaving an
Electrical idle
condition
—
UI Maximum time to meet all TX specifications when
transitioning from Electrical Idle to sending
differential data. This is considered a debounce
time for the TX to meet all TX specifications after
leaving Electrical Idle
TX-IDLE-TO-DIFF-DATA
RL
Differential
Return Loss
12
6
—
—
—
—
dB Measured over 50 MHz to 1.25 GHz. See Note 4
dB Measured over 50 MHz to 1.25 GHz. See Note 4
TX-DIFF
RL
Common Mode
Return Loss
TX-CM
Z
Z
DC Differential
TX Impedance
80
40
—
75
100
—
120
—
Ω
Ω
TX DC Differential mode Low Impedance
TX-DIFF-DC
TX-DC
Transmitter DC
Impedance
Required TX D+ as well as D- DC Impedance
during all states
L
Lane-to-Lane
Output Skew
—
500 +
2 UI
ps Static skew between any two Transmitter Lanes
within a single Link
TX-SKEW
C
AC Coupling
Capacitor
—
200
nF All Transmitters shall be AC coupled. The AC
coupling is required either within the media or within
the transmitting component itself. See Note 8.
TX
MPC8572E PowerQUICC III Integrated Processor Hardware Specifications, Rev. 4
Freescale Semiconductor
84
FREESCALE [ Freescale ]
