Datasheet

MPC8260A PowerQUICC™ II Integrated Communications Processor Hardware Specifications, Rev. 2.0
26 Freescale Semiconductor
Clock Configuration Modes
3.2 PCI Mode
The MPC8265 and the MPC8266 have three clocking modes: local, PCI host, and PCI agent. The clocking
mode is set according to three input pins—PCI_MODE, PCI_CFG[0], PCI_MODCK—as shown in
Table 15.
In addition, note the following:
NOTE: PCI_MODCK
In PCI mode only, PCI_MODCK comes from the LGPL5 pin and
MODCK_H[0–3] comes from {LGPL0, LGPL1, LGPL2, LGPL3}.
NOTE: Tval (Output Hold)
The minimum Tval = 2 when PCI_MODCK = 1, and the minimum Tval = 1
when PCI_MODCK = 0. Therefore, designers should use clock
configurations that fit this condition to achieve PCI-compliant AC timing.
NOTE
Clock configurations change only after POR is asserted.
1000_001 66 MHz 3.5 233 MHz 3 200 MHz
1000_010 66 MHz 3.5 233 MHz 3.5 233 MHz
1000_011 66 MHz 3.5 233 MHz 4 266 MHz
1000_100 66 MHz 3.5 233 MHz 4.5 300 MHz
1
Because of speed dependencies, not all of the possible configurations in Ta bl e 14 are applicable.
2
The user should choose the input clock frequency and the multiplication factors such that the frequency of the CPU
is equal to or greater than 150 MHz and the CPM ranges between 66–233 MHz.
3
Input clock frequency is given only for the purpose of reference. The user should set MODCK_H–MODCK_L so that
the resulting configuration does not exceed the frequency rating of the user’s part.
Table 15. MPC8265 and MPC8266 Clocking Modes
Pins
Clocking Mode
PCI Clock
Frequency Range
(MHZ)
PCI_MODE PCI_CFG[0] PCI_MODCK
1 — — Local bus —
0 0 0 PCI host 50–66
0 0 1 25–50
0 1 0 PCI agent 50–66
0 1 1 25–50
Table 14. Clock Configuration Modes
1
(continued)
MODCK_H–MODCK[1–3]
Input Clock
Frequency
2,3
CPM Multiplication
Factor
2
CPM
Frequency
2
Core Multiplication
Factor
2
Core
Frequency
2