SBAA528 February   2022 ADC12QJ1600-Q1 , TPS62912 , TPS62913

 

  1.   Trademarks
  2. 1Introduction and System Description
    1. 1.1 Introduction
      1. 1.1.1 ADC12QJ1600-Q1 Noise and Ripple Requirements
      2. 1.1.2 Power Supply Requirements for Clocks
      3. 1.1.3 TPS62913 Low-Noise and Low-Ripple Buck Converter
    2. 1.2 Block Diagram
    3. 1.3 Design Considerations
  3. 2Tests and Results
    1. 2.1 Test Methodology
    2. 2.2 Test Conditions
    3. 2.3 Test Results
  4. 3Conclusion
  5. 4References
  6.   A Appendix

2.3 Test Results

Performance tables and graphs comparing the original ADC12QJ1600-Q1 Original EVM with TPS62913 spread spectrum on and off modified board are shown below.

Table 2-1 Signal to Noise (SNR) Comparison Table
Frequency (MHz) Original QJ EVM (dBFS) TPS62913 W/O SS (dBFS) TPS62913 W/ SS (dBFS)
97 57.473 57.35 57.4
397 57.171 57.14 57.08
597 56.814 56.66 56.7
797 56.501 56.36 56.4
997 55.967 55.98 55.977
1497 54.765 55.02 55.01
GUID-20211028-SS0I-MXML-DK1P-RK8PWCPLQVBP-low.png Figure 2-5 Signal to Noise (SNR) Comparison Graph
Table 2-2 Spurious-Free Dynamic Range (SFDR) Comparison Table
Frequency (Hz) Original QJ EVM (dBFS) TPS62913 W/O SS (dBFS) TPS62913 W/ SS (dBFS)
97 67.92 67.41 67.28
397 70.799 70.91 69.95
597 64.663 65.57 65.6
797 65.847 65.42 65.51
997 64.302 64.14 64.2
1497 63.485 63.46 63.4
GUID-20211028-SS0I-WQXX-NCTR-TDM4JJLRNN3T-low.png Figure 2-6 Spurious-Free Dynamic Range Comparison Graph
GUID-20211028-SS0I-3GQR-49CJ-LHWXPC7280K1-low.png Figure 2-7 Noise Spectral Density Comparison Graph

The next plot, Figure 2-8, shows how no PSMR is observed with an analog input signal frequency of 347 MHz applied when using the original power design with SMPS and LDO, and the TPS62913 switching supply with and without spread sprectrum enabled.

GUID-20211028-SS0I-MCCQ-SNLJ-CPLT8PTWJ6JX-low.png Figure 2-8 PSMR Comparison of Original and TPS62913

Additionally, no visible modulation of the switcher power supply spur is seen around the carrier and at DC as seen in Figure 2-9.

GUID-20211028-SS0I-7MB5-PQRN-5JW0L2L1DXVP-low.png Figure 2-9 PSMR Comparison of Original and TPS62913 at DC
Table 2-3 Power Loss Comparison
Configuration Input Current Input Power
Original Power Supply Configuration with SMPSs + LDOs 486 mA 5.832 W
TPS62913 Power Supplies only-UPDATE 327 mA 3.924 W
Input Current and Power Savings-UPDATE 159 mA 1.908W

Figure 2-10 through Figure 2-12 are thermal images of the power supplies running when taking data for the performance comparison tables.

GUID-20210909-SS0I-VCLC-ZRH1-ZKZB0MX0ZMRT-low.jpg
Note: Original Board DC/DC Max Temp is 37.5 C
Figure 2-10 Original Switching Converters
GUID-20210909-SS0I-KJM2-4RKH-1WLM6LKZPHSP-low.jpg
Note: Original Board LDO Max Temp is 41.4 C
Figure 2-11 Original LDOs
GUID-20210929-SS0I-J2NV-KZ6W-JZKHGRXNQKB7-low.jpg Figure 2-12 TPS62913 Switching Converters
Note: TPS62913 Max Temp is 36.8 C