MC68HC08AS20 Datasheet, PDF (60/386 Pages) Freescale Semiconductor, Inc – M68HC08 Microcontrollers

6.3 Features
EEPROM features include:
• Byte, Block, or Bulk Erasable
• Nonvolatile Redundant Array Option
• Nonvolatile Block Protection Option
• Nonvolatile MCU Configuration Bits
• On-Chip Charge Pump for Programming/Erasing
6.4 Functional Description
Addresses $0800–$09FF are EEPROM locations. The 512 bytes of
EEPROM can be programmed or erased without an external voltage
supply. The EEPROM has a lifetime of 10,000 write-erase cycles in the
nonredundant mode. Reliability (data retention) is further extended if the
redundancy option is selected. EEPROM cells are protected with a
nonvolatile, 128-byte, block protection option. These options are stored
in the EEPROM nonvolatile register (EENVR) and are loaded into the
EEPROM array configuration register (EEACR) after reset or a read of
EENVR. The EEPROM array can also be disabled to reduce current.
6.4.1 EEPROM Programming
The unprogrammed state is a logic 1. Programming changes the state to
a logic 0. Only valid EEPROM bytes in the nonprotected blocks and
EENVR can be programmed. When the array is configured in the
redundant mode, programming the first 256 bytes ($0800–$08FF) will
also program the last 256 bytes ($0900–$09FF) with the same data.
Programming the EEPROM in the nonredundant mode is
recommended. Program the data to both locations before entering the
redundant mode.
Advance Information
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MC68HC08AS20 —Rev. 4.1
Freescale Semiconductor