SBAK043 April   2026 DAC39RF10-SP , DAC39RFS10-SP

 

  1.   1
  2.   2
  3.   Trademarks
  4. 1Introduction
  5. 2Single-Event Effects
  6. 3Device and Test Board Information
  7. 4Irradiation Facility and Setup
  8. 5Test Setup and Procedures
  9. 6Single-Event Latch-Up (SEL) Results
  10. 7Single-Event Functional Interrupt (SEFI) Results
    1. 7.1 Converter Performance and Digital (DUC + JESD204C Link) Hardness
    2. 7.2 Configuration Register Hardness
    3. 7.3 SPI Programming During Irradiation
  11. 8SEU Results
    1. 8.1 JESD204C Link Monitoring Results
    2. 8.2 Digital Up-Converter and NCO Upset Recovery
    3. 8.3 Estimating Upset Rates in Unprotected Data Paths
    4. 8.4 Event Rate Calculations
    5. 8.5 Summary of Radiation Hardness
  12. 9References
  13.   A Appendix: Recommendations for Hi-Rel Systems
    1.     A.1 Summary of Rad-Hard Design Features
    2.     A.2 SPI Programming
    3.     A.3 JESD204C Reliability
    4.     A.4 Equalizer Usage in Radiation Environments
    5.     A.5 NCO Reliability
    6.     A.6 NCO Frequency and Phase Correction (Strategy #1)
    7.     A.7 NCO Frequency Correction (Strategy #2)
    8.     A.8 NCO Self-Sync/Self-Coherent Mode (Strategy #3)

A.7 NCO Frequency Correction (Strategy #2)

This strategy also uses a periodic synchronization signal, but the NCO accumulator is not reset. Only the internal frequency registers inside each NCO are corrected by the synchronization signal. This ensures the NCO returns to the proper frequency after an upset occurs, but the phase of the NCO is not corrected. This strategy is appropriate for non-phased-array systems where an occasional, arbitrary phase jump can be tolerated.

  1. Program NCO_AR = 0 to configure the accumulator to NOT be reset by a synchronization event.
  2. Configure the NCO to use SYSREF as the synchronization source (NCO_SYNC_SRC = 2). Program SPI_SYNC = 1.
  3. Verify the SYSREF generator is configured for continuous/periodic output.
  4. Since the accumulator is not reset periodically, you have the freedom to program any NCO frequency regardless of the SYSREF frequency. The period of SYSREF must still be a multiple of the multi-frame/EMB period.
  5. While the NCO is operating, any upset to its internal frequency register will be corrected on the next SYSREF pulse (the frequency word is re-copied from the SEU-immune FREQ register). The NCO will operate for a brief time at an improper frequency before returning to the correct frequency (but with arbitrary phase).