MPC8610 Integrated Host Processor Hardware Specifications, Rev. 2
Electrical Characteristics
Freescale Semiconductor
24
SDn_REF_CLK and SDn_REF_CLK was designed to work with a spread spectrum clock (+0 to 0.5% spreading at 30–33 kHz
rate is allowed), assuming both ends have same reference clock. For better results use a source without significant unintended
modulation.
2.4.2
Real Time Clock Timing
The RTC input is sampled by the platform clock. The output of the sampling latch is then used as an input to the counters of the
PIC. There is no jitter specification. The minimum pulse width of the RTC signal should be greater than 2
× the period of the
platform clock. That is, minimum clock high time is 2
× tMPX, and minimum clock low time is 2 × tMPX. There is no minimum
RTC frequency; RTC may be grounded if not needed.
2.4.3
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.
Table 11provides the PCI/PCI-X reference clock AC timing specifications
for the MPC8610.
2.4.4
Platform Frequency Requirements for PCI-Express
The MPX platform clock frequency must be considered for proper operation of the high-speed PCI Express interface as
described below.
For proper PCI Express operation, the MPX clock frequency must be greater than or equal to:
527 MHz x (PCI-Express link width)
16 / (1 + cfg_net2_div)
Note that at MPX = 333 - 400 MHz, cfg_net2_div = 0 and at MPX > 400 MHz, cfg_net2_div = 1. Therefore, when operating
PCI Express in x8 link width, the MPX platform frequency must be 333-400 MHz with cfg_net2_div = 0 or greater than or
equal to 527 MHz with cfg_net2_div = 1.
Table 11. PCI
n_CLK AC Timing Specifications
Parameter/Condition
Symbol
Min
Typ
Max
Unit
Notes
PCI
n_CLK frequency
fPCICLK
16
—
133
MHz
—
PCI
n_CLK cycle time
tPCICLK
7.5
—
60
ns
—
PCI
n_CLK rise and fall time
tPCIKH, tPCIKL
0.6
1.0
2.1
ns
1, 2
PCI
n_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.