mpc970 Freescale Semiconductor, Inc, mpc970 Datasheet - Page 14

• Manufacturer Part Number: mpc970
• Description: Low Voltage Pll Clock Driver
• Manufacturer: Freescale Semiconductor, Inc

MPC970
Driving the PowerPC 603, PowerPC 604 and Pentium
Microprocessors
processors differ from the MPC 601 processor in that the
processor input clocks are at the same frequency as the
processor bus. A typical system for these processors will
include 8 – 16 clock loads on the processor bus. When the
MPC970 is taken out of the MPC601_Clk mode there are a
total of 8 “non PCI_CLK” outputs which can be run at the
processor bus speeds for these microprocessors. Since
each output can drive two series terminated transmission
lines the MPC970 can support point to point clock distribution
for up to 16 loads on the processor bus. In addition there will
be 7 PCI_CLK outputs which can drive up to 14 loads on the
PCI bus.
MOTOROLA
The PowerPC 603, PowerPC 604 and Pentium
If more clock loads are present on the processor bus the
14
PCI_CLKs can be configured to drive processor bus clock
loads in addition to the BCLKs or alternatively the clocking
roles of the BCLKs and PCI_CLKs can be reversed. Table 3
illustrates some useful frequency combinations for driving
PowerPC 603, PowerPC 604 or Pentium microprocessor
based systems.
Table Table 5. Common PowerPC 603, PowerPC 604
and Pentium System Frequencies
2x_PCLK
80
75
66
66
66
60
PCLK
80
75
66
66
66
60
33(1/2x)
BCLK
80(1x)
75(1x)
66(1x)
66(1x)
60(1x)
TIMING SOLUTIONS
BR1333 — Rev 6
66(PCLKEN)
PCI_CLK
26(1/3x)
25(1/3x)
33(1/2x)
30(1/2x)
66(1x)