AT87C5111-ICSIL datasheet(14/86 Pages) ATMEL

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AT8xC5111

4190A–8051–11/02

Reset and Power

Management

The power monitoring and management can be used to supervise the Power Supply

DD) and to start up properly when AT8xC5111 is powered up.

It consists of the features listed below and explained hereafter:

•

Power-off flag

•

Idle mode

•

Power-down mode

•

Reduced EMI mode

All these features are controlled by several registers, the Power Control register (PCON)

and the Auxiliary register (AUXR) detailed at the end of this section.

AUX register not available on all versions.

Functional Description

Figure 1 shows the block diagram of the possible sources of microcontroller reset.

Figure 1. Reset Sources

Notes:

1. RST pin available only on 48 and 52 pins versions.

2. RST pin available only on LPC versions.

Power-off Flag

When the power is turned off or fails, the data retention is not guaranteed. A Power-off

Flag (POF, Table 8 on page 15) allows to detect this condition. POF is set by hardware

during a reset which follows a power-up or a power-fail. This is a cold reset. A warm

reset is an external or a watchdog reset without power failure, hence which preserves

the internal memory content and POF. To use POF, test and clear this bit just after

reset. Then it will be set only after a cold reset.

Reset

RST Pin(1)

Hardware WD

PCA WD

RST Pin

(2)

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