
MPC8548E PowerQUICC III Integrated Processor Hardware Specifications, Rev. 9
Freescale Semiconductor
17
Input Clocks
4.3
eTSEC Gigabit Reference Clock Timing
The following table provides the eTSEC gigabit reference clocks (EC_GTX_CLK125) AC timing
specifications for the device.
4.4
PCI/PCI-X Reference Clock Timing
When the PCI/PCI-X controller is configured for asynchronous operation, the reference clock for the
PCI/PCI-x controller is not the SYSCLK input, but instead the PCIn_CLK. The following table provides
the PCI/PCI-X reference clock AC timing specifications for the device.
Table 6. EC_GTX_CLK125 AC Timing Specifications
Parameter/Condition
Symbol
Min
Typ
Max
Unit
Notes
EC_GTX_CLK125 frequency
fG125
—125
—
MHz
—
EC_GTX_CLK125 cycle time
tG125
—8—
ns
EC_GTX_CLK125 rise and fall time
L/TVDD = 2.5 V
L/TVDD = 3.3 V
tG125R, tG125F
——
0.75
1.0
ns
1
EC_GTX_CLK125 duty cycle
GMII, TBI
1000Base-T for RGMII, RTBI
tG125H/tG125
45
47
—
55
53
%2, 3
Notes:
1. Rise and fall times for EC_GTX_CLK125 are measured from 0.5 and 2.0 V for L/TVDD = 2.5 V, and from 0.6 and 2.7 V for
L/TVDD = 3.3 V.
2. Timing is guaranteed by design and characterization.
3. EC_GTX_CLK125 is used to generate the GTX clock TSECn_GTX_CLK for the eTSEC transmitter with 2% degradation.
EC_GTX_CLK125 duty cycle can be loosened from 47/53% as long as the PHY device can tolerate the duty cycle generated
100Base-T reference clock.
Table 7. PCIn_CLK AC Timing Specifications
At recommended operating conditions (see Table 2) with OVDD = 3.3 V ± 165 mV. Parameter/Condition
Symbol
Min
Typ
Max
Unit
Notes
PCIn_CLK frequency
fPCICLK
16
—
133
MHz
—
PCIn_CLK cycle time
tPCICLK
7.5
—
60
ns
—
PCIn_CLK rise and fall time
tPCIKH, tPCIKL
0.6
1.0
2.1
ns
1, 2
PCIn_CLK duty cycle
tPCIKHKL/tPCICLK
40
—
60
%
2
Notes:
1. Rise and fall times for SYSCLK are measured at 0.6 and 2.7 V.
2. Timing is guaranteed by design and characterization.