MPC106ARX66CE MOTOROLA [Motorola, Inc], MPC106ARX66CE Datasheet - Page 22

• Manufacturer Part Number: MPC106ARX66CE
• Description: PCI Bridge/Memory Controller
• Manufacturer: MOTOROLA [Motorola, Inc]

1.8 System Design Information
This section provides electrical and thermal design recommendations for successful application of the 106.
1.8.1 PLL Configuration
The 106 requires a single system clock input, SYSCLK. The SYSCLK frequency dictates the frequency of
operation for the PCI bus. An internal PLL on the MPC106 generates a master clock that is used for all of
the internal (core) logic. The master clock provides the core frequency reference and is phase-locked to the
SYSCLK input. The 60x processor, L2 cache, and memory interfaces operate at the core frequency. In the
5:2 clock mode (Rev. 4.0 only), the MPC106 needs to sample the 60x bus clock (on the LBCLAIM
configuration input) to resolve clock phasing with the PCI bus clock (SYSCLK).
The PLL is configured by the PLL[0–3] signals. For a given SYSCLK (PCI bus) frequency, the clock mode
configuration signals (PLL[0–3]) set the core frequency (and the frequency of the VCO controlling the
PLL lock). The supported core and VCO frequencies and the corresponding PLL[0–3] settings are
provided in Table 11.
22
Notes:
1
2
3
4
5
PLL[0–3] settings not listed are reserved. Some PLL configurations may select bus, CPU, or VCO frequencies
which are not useful, not supported, or not tested. See Section 1.4.2.1, “Clock AC Specifications,” for valid
SYSCLK and VCO frequencies.
5:2 clock modes are only supported by MPC106 Rev 4.0; earlier revisions do not support 5:2 clock modes.
The 5:2 modes require a 60x bus clock applied to the 60x clock phase (LBCLAIM) configuration input signal
during power-on reset, hard reset, and coming out of sleep and suspend power-saving modes.
In PLL-bypass mode, the SYSCLK input signal clocks the internal circuitry directly, the PLL is disabled, and
the core/SYSCLK ratio is set for 1:1 mode operation. This mode is intended for factory use and third-party tool
vendors only. Note also: The AC timing specifications given in this document do not apply in PLL-bypass
mode.
In clock-off mode, no clocking occurs inside the MPC106 regardless of the SYSCLK input.
PLL[0-3] = 0010 (2:1 Core/SYSCLK Ratio; X8 VCO multiplier) exists on the chip but will fail to lock 50% of the
time. Therefore, this configuration should not be used and 1:1 modes between 16-25MHz are not supported.
PLL[0–3]
0001
0100
0101
0110
0111
1000
0011
1111
1
MPC106 PCI Bridge/Memory Controller Hardware Specifications
Core/SYSCL
K Ratio
5:2
5:2
1:1
2:1
2:1
3:1
PLL-bypass
2
2
Clock off
Multiplier
4
VCO
Table 11. PLL Configuration
3
x4
x2
x4
x2
x4
x2
33.3 (133)
41.6 (166)
16.6 MHz
PCI Bus
—
—
—
—
Core Frequency (VCO Frequency) in MHz
SYSCLK clocks core circuitry directly
1x core/SYSCLK ratio implied
PCI Bus
40 (160)
no core clocking occurs
20 MHz
60(120)
—
—
—
—
PLL off
PLL off
PCI Bus
50 (200)
75 (150)
25 MHz
—
—
—
—
33.3 (133)
66.6 (133)
83.3 (166)
33.3 MHz
PCI Bus
—
—
—