SNAA386 November   2023 CDCE6214 , CDCE6214-Q1 , CDCE6214Q1TM , LMK00301 , LMK00304 , LMK00306 , LMK00308 , LMK00334 , LMK00334-Q1 , LMK00338 , LMK03318 , LMK03328 , LMK3H0102 , LMK6C , LMK6H , LMKDB1108 , LMKDB1120

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1Introduction
  5. 2Introduction to PCIe
    1. 2.1 The PCIe Link
  6. 3PCIe Clocking Architectures
    1. 3.1 Common Clock Architecture
    2. 3.2 Separate Reference Architecture
    3. 3.3 Spread Spectrum Clocking
    4. 3.4 PCIe REFCLK Topology
    5. 3.5 Noise Folding
  7. 4PCIe Clocking Specifications
    1. 4.1 REFCLK Output Format
    2. 4.2 PCIe Jitter Requirements
    3. 4.3 PCIe Time Domain Requirements
  8. 5REFCLK Measurement Technique
    1. 5.1 Clock Generator Measurement Results
      1. 5.1.1 PNA Measurement Result without SSC
      2. 5.1.2 PCIe Filtered PNA Result without SSC
      3. 5.1.3 PNA Measurement Result, With SSC
      4. 5.1.4 PCIe Filtered PNA Result, With SSC
      5. 5.1.5 Time Domain PCIe Measurement Result
    2. 5.2 Clock Buffer Measurement Results
      1. 5.2.1 PNA Measurement Result
      2. 5.2.2 PCIe Filtered PNA Result
      3. 5.2.3 Time Domain PCIe Measurement Result
  9. 6Texas Instruments Products with PCIe Compliance
  10. 7Summary
  11. 8References

5.2.3 Time Domain PCIe Measurement Result

Figure 5-6 is the time domain capture of the OUT0_P and OUT0_N outputs of the LMKDB1120 as measured by the oscilloscope. These results are exported to text files, which can be read by the Texas Instruments PCIe Reference Clock Analysis Tool and analyzed for compliance.

GUID-20231121-SS0I-SXKC-HB42-S2CSKH0HP2J1-low.png Figure 5-6 LMKDB1102 PCIe Time Domain Capture

Table 5-6 shows the result of the oscilloscope measurement after analysis. For the LMKDB1120, all of the parameters meet the limits specified in Table 4-2.

Table 5-6 LMKDB1120 PCIe Time Domain Results
Parameter Units Minimum Average Maximum Limit Status
VCross mV 334.15 346.91 361.14 250 mV to 550 mV Pass
VHigh mV 746.784 746.784 150 mV Pass
VLow mV –54.042 –54.042 –150 mV Pass
VRingback mV 557.354 586.954 100 mV Pass
Period ns 9.981 9.996 10.022 9.847 ns to 10.203 ns Pass
Duty Cycle % 49.343 49.493 49.663 40% to 60% Pass
VOvershoot mV 69.48 84.82 300 mV Pass
VUndershoot mV –67.09 –82.29 –300 mV Pass
Rising Edge Rate V/ns 2.067 2.336 2.615 0.6 V/ns to 4.0 V/ns Pass
Falling Edge Rate V/ns 1.974 2.2 2.629 0.6 V/ns to 4.0 V/ns Pass