t89c51rd2-slscl ATMEL Corporation, t89c51rd2-slscl Datasheet - Page 45

• Manufacturer Part Number: t89c51rd2-slscl
• Description: 0 To 40 Mhz Flash Programmable 8-bit Microcontroller
• Manufacturer: ATMEL Corporation

Figure 19. Power-down Exit Waveform
Table 27. State of Ports
4243G–8051–05/03
Power Down
Power Down
Mode
Idle
Idle
or
XTALB
XTALA
INT0
INT1
Program Memory
Active Phase
External
External
Internal
Internal
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:
Table 27 shows the state of ports during idle and power-down modes.
Port 0 can force a 0 level. A "one" will leave port floating.
ALE
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.
1
1
0
0
Power-down Phase
PSEN
1
1
0
0
Port Data
Port Data
Oscillator Restart Phase
PORT0
Floating
Floating
(1)
(1)
Port Data
Port Data
Port Data
Port Data
PORT1
Active Phase
Port Data
Port Data
Port Data
PORT2
Address
T89C51RD2
Port Data
Port Data
Port Data
Port Data
PORT3
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