MPC8240 datasheet(13/52 Pages) MOTOROLA

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MOTOROLA

MPC8240 Integrated Processor Hardware Specifications

Electrical and Thermal Characteristics

Figure 6 shows the PCI_SYNC_IN input clock timing diagram, and Figure 7 shows the DLL locking range

loop delay versus frequency of operation.

Figure 6. PCI_SYNC_IN Input Clock Timing Diagram

DLL lock range with DLL_STANDARD = 0 (default)

≤ (NTclk – Tclk/2 – tloop – tfix0)

≤ 7

Frequency of operation (OSC_IN)

MHz

OSC_IN cycle time

OSC_IN rise and fall times

—

OSC_IN duty cycle measured at 1.4 V

OSC_IN frequency stability

—

100

ppm

OSC_IN VIH (loaded)

2.0

OSC_IN VIL (loaded)

0.8

Notes:

1. These specifications are for the default driver strengths indicated in Table 4.

2. Rise and fall times for the PCI_SYNC_IN input are measured from 0.4 to 2.4 V.

3. Specification value at maximum frequency of operation.

4. Relock time is guaranteed by design and characterization. Relock time is not tested.

5. Rise and fall times for the OSC_IN input are guaranteed by design and characterization. OSC_IN input rise and fall

times are not tested.

6. Relock timing is guaranteed by design. PLL-relock time is the maximum amount of time required for PLL lock after

a stable VDD and PCI_SYNC_IN are reached during the reset sequence. This specification also applies when the

PLL has been disabled and subsequently re-enabled during sleep mode. Also note that HRST_CPU/HRST_CTRL

must be held asserted for a minimum of 255 bus clocks after the PLL-relock time during the reset sequence.

7. DLL_STANDARD is bit 7 of the PMC2 register <72>. N is a non-zero integer (1 or 2). Tclk is the period of one

SDRAM_SYNC_OUT clock cycle in ns. tloop is the propagation delay of the DLL synchronization feedback loop (PC

board runner) from SDRAM_SYNC_OUT to SDRAM_SYNC_IN in ns; 6.25 inches of loop length (unloaded PC

board runner) corresponds to approximately 1 ns of delay. tfix0 is a fixed delay inherent in the design when the DLL

is at tap point 0 and the DLL is contributing no delay; tfix0 equals approximately 3 ns. See Figure 7 for DLL3 locking

ranges.

8. Pin-to-pin skew includes quantifying the additional amount of clock skew (or jitter) from the DLL besides any

intentional skew added to the clocking signals from the variable length DLL synchronization feedback loop, that is,

the amount of variance between the internal sys_logic_clk and the SDRAM_SYNC_IN signal after the DLL is

locked. While pin to pin skew between SDRAM_CLKs can be measured, the relationship between the internal

sys_logic_clk and the external SDRAM_SYNC_IN cannot be measured and is guaranteed by design.

Table 7. Clock AC Timing Specifications (continued)

At recommended operating conditions (see Table 2) with LVDD = 3.3 V ± 0.3 V

Num

Characteristic and Condition 1

Min

Max

Unit

Notes

VM = Midpoint Voltage (1.4 V)

CVIL

CVIH

PCI_SYNC_IN

Freescale Semiconductor, Inc.

For More Information On This Product,

Go to: www.freescale.com

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