MPC7448 datasheet(16/60 Pages) FREESCALE

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MPC7448 RISC Microprocessor Hardware Specifications, Rev. 3

Freescale Semiconductor

Electrical and Thermal Characteristics

Figure 3 provides the SYSCLK input timing diagram.

Figure 3. SYSCLK Input Timing Diagram

5.2.2

Processor Bus AC Specifications

Table 9 provides the processor bus AC timing specifications for the MPC7448 as defined in Figure 4 and

Figure 5.

Internal PLL relock time

—

100

—

100

—

100

—

100

μs7

Notes:

1. Caution: The SYSCLK frequency and PLL_CFG[0:5] settings must be chosen such that the resulting SYSCLK (bus)

frequency, processor core frequency, and PLL (VCO) frequency do not exceed their respective maximum or minimum

operating frequencies. Refer to the PLL_CFG[0:5] signal description in Section 9.1.1, “PLL Configuration,” for valid

PLL_CFG[0:5] settings.

2. Actual maximum system bus frequency is system-dependent. See Section 5.2.1, “Clock AC Specifications.”

3. Rise and fall times for the SYSCLK input measured from 0.4 to 1.4 V

4. Timing is guaranteed by design and characterization.

5. Guaranteed by design

6. The SYSCLK driver’s closed loop jitter bandwidth should be less than 1.5 MHz at –3 dB.

7. Relock timing is guaranteed by design and characterization. PLL-relock time is the maximum amount of time required for PLL

lock after a stable VDD and SYSCLK are reached during the power-on reset sequence. This specification also applies when

the PLL has been disabled and subsequently re-enabled during sleep mode. Also note that HRESET must be held asserted

for a minimum of 255 bus clocks after the PLL-relock time during the power-on reset sequence.

8. This reflects the maximum and minimum core frequencies when the dynamic frequency switching feature (DFS) is disabled.

fcore_DFS provides the maximum and minimum core frequencies when operating in a DFS mode.

9.This specification supports the Dynamic Frequency Switching (DFS) feature and is applicable only when one of the DFS

modes (divide-by-2 or divide-by-4) is enabled. When DFS is disabled, the core frequency must conform to the maximum and

minimum frequencies stated for fcore.

10.Use of the DFS feature does not affect VCO frequency.

Table 8. Clock AC Timing Specifications (continued)

At recommended operating conditions. See Table 4.

Characteristic

Symbol

Maximum Processor Core Frequency (Speed Grade)

Unit

Notes

1000 MHz

1420 MHz

1600 MHz

1700 MHz

Min

Max

Min

Max

Min

Max

Min

Max

SYSCLK

CVIH

CVIL

VM = Midpoint Voltage (OVDD/2)

tSYSCLK

tKR

tKF

tKHKL

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