MPC875 Freescale Semiconductor, Inc, MPC875 Datasheet - Page 17

• Manufacturer Part Number: MPC875
• Description: Mpc875 Powerquicc Integrated Communications Processor
• Manufacturer: Freescale Semiconductor, Inc

11 Bus Signal Timing
The maximum bus speed supported by the MPC875/MPC870 is 80 MHz. Higher-speed parts must be
operated in half-speed bus mode (for example, an MPC875/MPC870 used at 133 MHz must be configured
for a 66 MHz bus).
Table 9
Table 10
The timing for the MPC875/MPC870 bus shown
a 0-pF load for minimum delays. CLKOUT assumes a 100-pF load maximum delay
Freescale Semiconductor
Core frequency
Bus frequency
Core frequency
Bus frequency
Num
B1a
B1b
B1c
B1d
B1
shows the frequency ranges for standard part frequencies in 2:1 bus mode.
Bus period (CLKOUT), see
EXTCLK to CLKOUT phase skew—If
CLKOUT is an integer multiple of EXTCLK,
then the rising edge of EXTCLK is aligned with
the rising edge of CLKOUT. For a non-integer
multiple of EXTCLK, this synchronization is
lost, and the rising edges of EXTCLK and
CLKOUT have a continuously varying phase
skew.
CLKOUT frequency jitter peak-to-peak
Frequency jitter on EXTCLK
CLKOUT phase jitter peak-to-peak for
OSCLK ≥ 15 MHz
CLKOUT phase jitter peak-to-peak for
OSCLK < 15 MHz
provides the bus operation timing for the MPC875/MPC870 at 33, 40, 66, and 80 MHz.
Table 8. Frequency Ranges for Standard Part Frequencies (1:1 Bus Mode)
Table 9. Frequency Ranges for Standard Part Frequencies (2:1 Bus Mode)
Part Frequency
Table 8
Characteristic
MPC875/MPC870 PowerQUICC™ Hardware Specifications, Rev. 4
Part Frequency
shows the frequency ranges for standard part frequencies in 1:1 bus mode, and
Table 8
Table 10. Bus Operation Timings
Min
Table
–2
—
—
—
—
—
33 MHz
Min
40
20
Max
0.50
10, assumes a 50-pF load for maximum delays and
+2
—
1
4
5
66 MHz
Min
—
–2
—
—
—
—
66.67
33.33
Max
40 MHz
Min
40
40
Max
0.50
+2
—
1
4
5
66 MHz
Min
40
20
Min
80 MHz
–2
—
—
—
—
—
66 MHz
66.67
66.67
Max
Max
Max
0.50
80
40
+2
—
1
4
5
Min
Min
–2
40
40
—
—
—
—
—
80 MHz
Min
Bus Signal Timing
40
20
80 MHz
133 MHz
Max
0.50
+2
—
1
4
5
Max
80
80
Max
133
66
Unit
ns
ns
ns
ns
ns
%
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