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Background

ST-5 EEPROM Anomaly Kenneth Li Code 561 NASA/GSFC Kenneth.e.li@nasa.gov 301-286-5777 October 12, 2005. Background. Program : New Millenium Program, Space Technology – 5 (ST-5) Device : Maxwell 79C0832 EEPROM (256Kx32) MCM containing 8 1Mbit Hitachi 128Kx8 Die

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  1. ST-5 EEPROM AnomalyKenneth LiCode 561NASA/GSFCKenneth.e.li@nasa.gov301-286-5777October 12, 2005 EEPROM Reliability Workshop - NASA GSFC, Oct 12, 2005

  2. Background • Program: New Millenium Program, Space Technology – 5 (ST-5) • Device: Maxwell 79C0832 EEPROM (256Kx32) • MCM containing 8 1Mbit Hitachi 128Kx8 Die • Package: 96-Pin RAD-PAK Quad Flat pack • Implementation: Holds Boot and Flight Code for Mongoose 5 Processor EEPROM Reliability Workshop - NASA GSFC, Oct 12, 2005

  3. Anomaly • Occurred on Flight Unit #1 during Ground Testing (Nov 2003) • Different EEPROM Checksums recorded before and after Thanksgiving break. EEPROM Reliability Workshop - NASA GSFC, Oct 12, 2005

  4. EEPROM Reads Good Read – Expected 0s occur in ~60ns (Read BFC92244 - Data bits should show 0) CH1=D2 (on U58) CH2=D3 (on U58) CH3=D4 (on U58) CH4=EEP1_OE_N (JP42-12) – 600ns read cycle (used BNC cable instead of scope probe) Suspect Read – Expected 0s occur in up to 520ns Read BFC61628 - Data bits should show 0 CH1=D3 (on U58) CH2=D4 (on U58) CH3=EEP1_CE_N (JP42-8) CH4=EEP1_OE_N (JP42-12) EEPROM Reliability Workshop - NASA GSFC, Oct 12, 2005

  5. EEPROM Writes All on U58 pins: CH1=D27 CH2=D28 CH3=CE0 CH4=WE_N Write a8650000 to BFC61944 All on U58 pins: CH1=D27 – writing a data 1 CH2=D28 – writing a data 1 CH3=CE0 CH4=WE_N TDH =10ns,min Write 7fc30000 to BFC61910 Result: Appears Write timing violates EEPROM Data Sheet Data Hold Spec EEPROM Reliability Workshop - NASA GSFC, Oct 12, 2005

  6. Status • Appears EEPROM write timing violates datasheet spec • Signals generated by FPGA • FPGA redesigned to meet datasheet timing • However, suspect EEPROM replaced (Project decision) • No anomalies seen since • Suspect EEPROM installed onto ETU board • Testing of suspect EEPROM with new FPGA timing never performed by ST-5 (WOA still open) • Weak cells caused by inadequate write timing or by suspect EEPROM device (TBD) EEPROM Reliability Workshop - NASA GSFC, Oct 12, 2005

  7. Miscellaneous – BAE Systems • BAE Systems has observed bit failures on EEPROMs in RAD750s • Suspect parts removed and sent back to Maxwell • Discovered at-speed timing not used in Maxell data retention tests • Consultation with Maxwell resulted in additional data retention screening, on request, comprising: • Program EEPROM to 0s with S/W write protect off & verify 0s with at speed timing • Burn-in for 72 hrs at 150C (unpowered) • Maxwell did not power off parts during their data retention tests. • Verify 0s at speed and deliver device programmed to 0s. EEPROM Reliability Workshop - NASA GSFC, Oct 12, 2005

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