AT89C55WD Atmel Corporation, AT89C55WD Datasheet - Page 19

• Manufacturer Part Number: AT89C55WD
• Manufacturer: Atmel Corporation

Specifications of AT89C55WD

• Flash (kbytes): 20 Kbytes
• Max. Operating Frequency: 24 MHz
• Cpu: 8051-12C
• Max I/o Pins: 32
• Uart: 1
• Sram (kbytes): 0.25
• Operating Voltage (vcc): 4.0 to 6.0
• Timers: 3
• Watchdog: Yes

1921D–MICRO–6/08
Figure 18-1. Oscillator Connections
Note:
Figure 18-2. External Clock Drive Configuration
Table 18-1.
Mode
Idle
Idle
Power-down
Power-down
C1, C2 = 30 pF ± 10 pF for Crystals
Status of External Pins During Idle and Power-down Modes
= 40 pF ± 10 pF for Ceramic Resonators
Program
Memory
Internal
External
Internal
External
OSCILLATOR
EXTERNAL
SIGNAL
ALE
1
1
0
0
NC
C2
C1
PSEN
1
1
0
0
PORT0
Float
Float
Data
Data
XTAL2
XTAL1
GND
XTAL2
XTAL1
GND
PORT1
Data
Data
Data
Data
AT89C55WD
Address
PORT2
Data
Data
Data
PORT3
Data
Data
Data
Data
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