SLVAEW7 September   2020 ADC12DJ5200RF , LMK00304 , LMK04828 , LMX2594 , TPS62912 , TPS62913

 

  1.   Trademarks
  2. 1Introduction and System Description
    1. 1.1 Introduction
      1. 1.1.1 ADC12DJ5200 Noise and Ripple Requirements
      2. 1.1.2 Power Supply Requirements for Wideband RF PLL and 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. 5Appendix

1.2 Block Diagram

The original ADC12DJ5200 Rev C evaluation module used several SMPS with LDO followers to provide power to the ADC and clock rails. The 3.3V clock rails require low phase noise and low jitter. The 1.1 V analog rail (VA11) requires a separate LDO for the low noise requirements, while the 1.9 V analog and digital rails (VA19 and VD19) is supplied by a single supply as shown in Figure 1-4.

GUID-20200914-CA0I-2XB3-KJZF-19V1QMDMKBHK-low.gifFigure 1-4 Original Power Block Diagram for ADC12DJ5200 Rev C Evaluation Module

The original EVM power supply is outlined in blue and shown in Figure 1-5.

GUID-20200914-CA0I-5H3Q-KR9D-VXG9VSP2MPVC-low.gifFigure 1-5 Image of board with Switchers and LDO's outlined in Blue

In the revised design, the LDOs are removed and the TPS62913 low-ripple, low-noise SMPS is used instead. This design presents a simplified power supply network for the ADC, where all three power domains are supplied from a DC/DC regulator, with a separate supply for the 3.3-V clock, as shown in Figure 1-6. This implementation improves the efficiency and reduces the part count in comparison to a solution using LDOs while maintaining the output voltage ripple and noise requirements of the ADC and clock for good performance.

GUID-20200914-CA0I-JZMQ-8JL5-X114B0LSVCBP-low.gifFigure 1-6 Power Block Diagram for ADC12DJ5200 Rev C Evaluation Module with TPS62913

The updated EVM power supply with the TPS62913 is outlined in blue and shown in Figure 1-7.

GUID-20200914-CA0I-NSJC-DJ4K-XSDPNPDR4HZZ-low.gifFigure 1-7 Image of board with TPS62913 Switchers outlined in Blue

The schematics for the 3.3-V, 1.1-V, and 1.9-V rails can be found in the Section 5.

Table 1-1 ADC12DJ5200 Evaluation Module Component Comparison
ComponentOriginal Rev CRev C with TPS62913
Switching Power Supplies4 x LMS3635M (4mm x 5mm ea)4 x TPS62913 (2mm x 2mm ea)
LDO's3 x TPS7A8400 (3.5mm x 3.5mm ea)None
Size of Power Supplies116.75 sqmm + passives16 sqmm + passives