AT91SAM7A3 datasheet(21/39 Pages) ATMEL

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6042DS–ATARM–14-Dec-06

AT91SAM7A3

9.2

Reset Controller

The Reset Controller is based on three power-on reset cells. It gives the status of the last reset,

indicating whether it is a general reset, a wake-up reset, a software reset, a user reset or a

watchdog reset. In addition, it controls the internal resets and the NRST pin output. It shapes a

signal on the NRST line, guaranteeing that the length of the pulse meets any requirement.

9.3

Clock Generator

The Clock Generator embeds one low-power RC Oscillator, one Main Oscillator and one PLL

with the following characteristics:

– RC Oscillator ranges between 22 KHz and 42 KHz

– Main Oscillator frequency ranges between 3 and 20 MHz

– Main Oscillator can be bypassed

– PLL output ranges between 80 and 220 MHz

It provides SLCK, MAINCK and PLLCK.

Figure 9-2.

Clock Generator Block Diagram

9.4

Power Management Controller

The Power Management Controller uses the Clock Generator outputs to provide:

– the Processor Clock PCK

– the Master Clock MCK

– the USB Clock UDPCK

– all the peripheral clocks, independently controllable

– four programmable clock outputs

The Master Clock (MCK) is programmable from a few hundred Hz to the maximum operating fre-

quency of the device.

The Processor Clock (PCK) switches off when entering processor idle mode, thereby reducing

power consumption while waiting an interrupt.

Power

Management

Controller

XIN

XOUT

PLLRC

Slow Clock

SLCK

Main Clock

MAINCK

PLL Clock

PLLCK

Control

Status

Embedded

Oscillator

Main

Oscillator

PLL and

Divider

Clock Generator

AT91SAM7A3 Datasheet(PDF) 21 Page - ATMEL Corporation

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