AT89C51IC2-SLSCM datasheet(70/146 Pages) ATMEL

70 / 146 page

AT89C51IC2

4301A–8051–01/04

Figure 25. Power-down Exit Waveform

Exit from Power-down by reset redefines all the SFRs, exit from Power-down by exter-

nal interrupt does no affect the SFRs.

Exit from Power-down by either reset or external interrupt does not affect the internal

RAM content.

Note:

If idle mode is activated with Power-down mode (IDL and PD bits set), the exit sequence

is unchanged, when execution is vectored to interrupt, PD and IDL bits are cleared and

idle mode is not entered.

Table 55 shows the state of ports during idle and power-down modes.

Port 0 can force a 0 level. A "one" will leave port floating.

INT1

INT0

XTALA

Power-down Phase

Oscillator Restart Phase

Active Phase

XTALB

Table 55. State of Ports

Mode

Program Memory

ALE

PSEN

PORT0

PORT1

PORT2

PORT3

Idle

Internal

Port Data

(1)

Port Data

Idle

External

Floating

Port Data

Address

Port Data

Power Down

Internal

Port Data

(1)

Port Data

Power Down

External

Floating

Port Data

AT89C51IC2-SLSCM Datasheet(PDF) 70 Page - ATMEL Corporation

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