SBAA637 June   2024 AFE7900 , AFE7901 , AFE7903 , AFE7906 , AFE7950 , AFE7950-SP , AFE7951 , AFE7953 , AFE7954 , AFE7955 , AFE7958

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1 Introduction
  5. 2 SPI Failure During Bring-Up
    1. 2.1 Detail Regarding Chip Readouts
    2. 2.2 Failure and Fix for Chip Read Check
    3. 2.3 Poll Check for SPI Access for PLL Page
    4. 2.4 Failure and Fix for the SPI Poll Check for PLL Page Access
    5. 2.5 Read Check Indicating Status of Fuse Farm Autoload
    6. 2.6 Failure and Fix for Autoload Read Check
  6. 3 Macro Failure Breaking the Bring-Up Flow
    1. 3.1 Read Check for Macro Error and Poll Check for Macro Done
    2. 3.2 Failure and Fix for Macro Error and Poll check for Macro Done
  7. 4 AFE PLL Failure
    1. 4.1 Read Check for PLL Lock
    2. 4.2 Failure and Fix for Read Check of PLL
  8. 5 AFE Internal Sysref Flag Failure
    1. 5.1 Read Check Status of Sysref Flag Bit
    2. 5.2 Failure and Fix for Read Check Status of Sysref Flag Bit
  9. 6 JESD Link Check Failure
    1. 6.1 Multiple Read Checks Indicating Status of JESD Linkup
    2. 6.2 Failure and Fix for JESD Error
  10. 7 Validating Serdes and JESD Link using CAPI
    1. 7.1 Useful Serdes Debug CAPIs
    2. 7.2 Useful JESD Debug CAPIs
  11. 8 TX Chain Validation
  12. 9 RX Chain Validation
  13. 10Device Health
  14. 11Summary
  15. 12References

5.2 Failure and Fix for Read Check Status of Sysref Flag Bit

Failure in read check sysref status points towards improper pin sysref. Make sure sysref frequency and level are in expected range. If using pulse sysref mode is selected, common mode voltage must be supplied through external driver along with swing limits. In case of continuous sysref mode is selected, AC coupling capacitor can be used and device can force common mode internally for sysref pins around 0.7V.

Table 5-1 Sysref Electrical Characteristics
Differential Inputs: ±Mode A
FSYSREFMAX SYSREF Input Frequency Maximum 1 GHz
VSWINGSRMAX SYSREF Input SWING Maximum 1.8 VPPdiff
VSWINGSRMIN SYSREF Input SWING Minimum fREF < 500MHz 0.3 VPPdiff
fREF > 500MHz 0.6 VPPdiff
VCOMSRMAX SYSREF Input Common Mode Voltage Maximum 0.8 V
VCOMSRMIN SYSREF Input Common Mode Voltage Minimum 0.6 V
ZT Input Termination Differential 100 Ω
CL Input Capacitance Each pin to GD 500 pF