1. 120/MAPLD 2004 Maintaining Data Integrity in EEPROM’s Ed Patnaude Maxwell Technologies San Diego, Ca

2. Patnaude 2 120/MAPLD 2004 Contents EEPROM Technology Sources of Data Corruption Maintaining Data Integrity Summary

3. Patnaude 3 120/MAPLD 2004 EEPROM Technology Most EEPROM’s utilize some variation of the “Floating Gate Technology” A positively charged gate is read as a logic 0.

4. Patnaude 4 120/MAPLD 2004 Sources of Data Corruption Software Errors Insufficient Hardware Protection Programming Issues

5. Patnaude 5 120/MAPLD 2004 Sources of Data Corruption Software Errors Inadvertent Writes Improper Timing / Buss Contention Programming Across Page Boundaries

6. Patnaude 6 120/MAPLD 2004 Sources of Data Corruption Insufficient Hardware Protection Uncontrolled Power On/Off Uncontrolled Inputs Excessive Power Supply Noise Data Buss Contention No Hardware Write Protection Implemented

7. Patnaude 7 120/MAPLD 2004 Sources of Data Corruption Programming Issues Setting Write Protect, or Reset, active during a write cycle will halt programming resulting in corrupt data. Insufficient supply voltage, during a program cycle, can result in incorrect data being stored. Exceeding the manufactures write cycle endurance specification can cause permanent damage to the memory cells leaving them un-programmable.

8. Patnaude 8 120/MAPLD 2004 Maintaining Data Integrity Hardware Protection Software Protection Proper Power Cycling Error Detection and Correction (EDAC) Power Supply Supervisory Circuitry Contingency Plan

9. Patnaude 9 120/MAPLD 2004 Maintaining Data Integrity Hardware Protection Most EEPROM’s have a RESET or Write Protect input, when set active, all erase/writes operations are blocked.

10. Patnaude 10 120/MAPLD 2004 Maintaining Data Integrity Software Data Protection (SDP) SDP locks the memory preventing unintentional erase/writes from occurring. Normally implemented using the JEDEC Standard Algorithm SDP will only protect the memory contents when the supply voltage is within the normal operating range.

11. Patnaude 11 120/MAPLD 2004 Maintaining Data Integrity Proper Power Cycling Allow Vcc to reach proper operating level before initiating any Reads or Writes to the EEPROM. Enable the EEPROM Hardware Write Protection, or Reset, prior to power down. Do not remove power while a write cycle is in process.

12. Patnaude 12 120/MAPLD 2004 Maintaining Data Integrity Error Detection and Protection Parity Bits Checksum Cyclic Redundancy Code Error Correction Codes Hamming Code Reed-Solomon

13. Patnaude 13 120/MAPLD 2004 Maintaining Data Integrity Power Supervisory Circuitry Monitor Supply Voltages and provide a RESET signal when the voltage drops below a pre-described level

14. Patnaude 14 120/MAPLD 2004 Maintaining Data Integrity Have a Contingency Plan Always verify data after a program cycle to assure an error has not occurred and re-program if necessary. Data retention time can be increased by periodically rewriting the data to the EEPROM. Have the ability to relocate bad data bytes. Use Redundancy if at all possible.

15. Patnaude 15 120/MAPLD 2004 Summary A robust hardware and software design, along with a contingency plan should corruption occur, can greatly minimize the risk of system failure due to data corruption in a EEPROM.