Specifications

B.2 Clock rate restrictions

The default clock rates for reliable operation are:

CPUCLK 210MHz

MPMCCLK 70MHz

HCLK70MHz

HCLKEXT 35MHz

MBXCLK 70MHz

SMCLK 50MHz

If you have added one or more RealView Logic Tiles, you might need to reduce these clock rates.

For timing on the buses and peripherals, see:

AHB bus timing on page B-6

Memory timing on page B-7

Peripheral timing on page B-7.

Caution

The ICS307 programmable oscillators OSC0, OSC1, OSC2, OSC3, and OSC4 can be programmed to deliver very high clock signals (200MHZ). The only ARM926EJ-S PXP Development Chip clock input that can function at this frequency is

PLLCLKEXT.

Also, the settings for VCO divider, output divider, and output select values are interrelated and must be set correctly. Some combinations of settings do not result in stable operation. For more information on the ICS clock generator and a frequency calculator, see the ICS web site at www.icst.com.

ARM DUI 0224I

Copyright © 2003-2010 ARM Limited. All rights reserved.

B-5

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ARM ARM DUI 0224I manual Clock rate restrictions, Default clock rates for reliable operation are