AT89C51AC2 Atmel Corporation, AT89C51AC2 Datasheet - Page 3

• Manufacturer Part Number: AT89C51AC2
• Manufacturer: Atmel Corporation

Specifications of AT89C51AC2

• Flash (kbytes): 32 Kbytes
• Max. Operating Frequency: 40 MHz
• Cpu: 8051-12C
• Max I/o Pins: 34
• Uart: 1
• Adc Channels: 8
• Adc Resolution (bits): 10
• Adc Speed (ksps): 62.5
• Sram (kbytes): 1.25
• Eeprom (bytes): 2048
• Self Program Memory: API
• Operating Voltage (vcc): 3.0 to 5.5
• Timers: 4
• Isp: UART
• Watchdog: Yes

11. C51 Core
12. Timer0/1
13. EEPROM
4159G–8051–05/06
When exiting power-down mode by interrupt while CPU is in X2 mode, it leads to bad execution of the first instruction
run when CPU restarts.
Workaround
Set the CPU in X1 mode directly before entering power-down mode.
When the Timer0 is in X1 mode and Timer1 in X2 mode and vice versa, extra interrupt may randomly occurred for
Timer0 or Timer1.
Workaround
Use the same mode for the two timers.
Program lock-up can be experienced when using Atmel FLIP software or a custom In system Programming tools to
write in the internal EEPROM. This problem occurs with clock frequency > 12MHz in X2 mode or 24MHz in X1 mode.
Neither the code Flash nor the EEPROM are corrupted by the lock-up. Although the EEPROM cannot be written by the
bootloader.
This problem does not affect the capability to erase, read and write into the code Flash and the additional bytes with In-
System Programming as Atmel FLIP.
This problem is bootloader related and doesn’t affect the capability for the user to read and write into the EEPROM.
This problem is technology dependant. The likelihood of experiencing the problem is low at Clock frequency > 24 MHz
in X1 mode and null below. A reset can be applied to recover from the lock-up.
Workaround
The following process can be done to work around the problem.
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A NOP instruction has to be inserted after the load instruction in the application.
MOVX @DPTR,A ;Load Column latches
NOP ; ADDED INSTRUCTION
Load of the column latch in the bootloader area.
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Extra interrupt.
Lock-up during ISP write.
Bad Exit of Power-down in X2 Mode
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