AT80C51RD2-3CSUM Atmel, AT80C51RD2-3CSUM Datasheet - Page 59

• Manufacturer Part Number: AT80C51RD2-3CSUM
• Description: IC, 8BIT MCU, 80C51, 40MHZ, DIP-40
• Manufacturer: Atmel

Specifications of AT80C51RD2-3CSUM

• Controller Family/series: 80C51
• No. Of I/o's: 32
• Ram Memory Size: 1280Byte
• Cpu Speed: 40MHz
• No. Of Timers: 3
• No. Of Pwm Channels: 5
• Digital Ic Case Style: DIP
• Core Size: 8 Bit
• Rohs Compliant: Yes
• Processor Series: AT80x
• Core: 8051
• Data Bus Width: 8 bit
• Program Memory Type: ROMLess
• Data Ram Size: 1280 B
• Interface Type: UART, SPI
• Maximum Clock Frequency: 60 MHz
• Number Of Programmable I/os: 32
• Number Of Timers: 3
• Operating Supply Voltage: 2.7 V to 5.5 V
• Maximum Operating Temperature: + 70 C
• Mounting Style: Through Hole
• Package / Case: PDIL-40
• 3rd Party Development Tools: PK51, CA51, A51, ULINK2
• Minimum Operating Temperature: 0 C
• Cpu Family: AT80
• Device Core: 8051
• Device Core Size: 8b
• Frequency (max): 40MHz
• Program Memory Size: Not Required
• Total Internal Ram Size: 1.25KB
• # I/os (max): 32
• Number Of Timers - General Purpose: 3
• Operating Supply Voltage (typ): 3.3/5V
• Operating Supply Voltage (max): 5.5V
• Operating Supply Voltage (min): 2.7V
• Instruction Set Architecture: CISC
• Operating Temp Range: -40C to 85C
• Operating Temperature Classification: Industrial
• Mounting: Through Hole
• Pin Count: 40
• Package Type: PDIP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

15.2
4113D–8051–01/09
WDT During Power-down and Idle
Table 15-2.
WDTPRG - Watchdog Timer Out Register (0A7h)
Reset Value = XXXX X000
In Power-down mode the oscillator stops, which means the WDT also stops. While in Power-
down mode the user does not need to service the WDT. There are 2 methods of exiting Power-
down mode: by a hardware reset or via a level activated external interrupt which is enabled prior
to entering Power-down mode. When Power-down is exited with hardware reset, servicing the
WDT should occur as normal, whenever the AT80C51RD2 is reset. Exiting Power-down with an
interrupt is significantly different. The interrupt is held low long enough for the oscillator to stabi-
lize. When the interrupt is brought high, the interrupt is serviced. To prevent the WDT from
resetting the device while the interrupt pin is held low, the WDT is not started until the interrupt is
pulled high. It is suggested that the WDT be reset during the interrupt service routine.
To ensure that the WDT does not overflow within a few states of exiting of power-down, it is bet-
ter to reset the WDT just before entering power-down.
In the Idle mode, the oscillator continues to run. To prevent the WDT from resetting the
AT80C51RD2 while in Idle mode, the user should always set up a timer that will periodically exit
Idle, service the WDT, and re-enter Idle mode.
Number
Bit
7
7
6
5
4
3
2
1
0
-
WDTPRG Register
Mnemonic Description
Bit
S2
S1
S0
6
-
-
-
-
-
-
Reserved
The value read from this bit is undetermined. Do not try to set this bit.
WDT Time-out select bit 2
WDT Time-out select bit 1
WDT Time-out select bit 0
S2S1 S0Selected Time-out
0
0
0
0
1
1
1
1
0
0
1
1
0
0
1
1
5
-
0
1
0 (2
1
0
1 (2
0
1
16
19
- 1) machine cycles, 65. 5 ms @ F
- 1) machine cycles, 542 ms @ F
(2
(2
(2
(2
(2
(2
14
15
17
18
20
21
4
-
- 1) machine cycles, 16. 3 ms @ F
- 1) machine cycles, 32.7 ms @ F
- 1) machine cycles, 131 ms @ F
- 1) machine cycles, 262 ms @ F
- 1) machine cycles, 1.05 s @ F
- 1) machine cycles, 2.09 s @ F
3
-
S2
2
osc
osc
AT80C51RD2
=12 MHz
=12 MHz
osc
osc
osc
osc
osc
=12 MHz
=12 MHz
osc
=12 MHz
=12 MHz
=12 MHz
=12 MHz
S1
1
S0
0
59