SNLA434 November   2023 DP83TC812R-Q1 , DP83TD510E , DP83TG720R-Q1 , LMK1C1103 , LMK1C1104 , LMK5B12204 , LMK6C

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1Introduction
  5. 2Power Supply
    1. 2.1 Internal Supply Rails
    2. 2.2 External Supply Lines
    3. 2.3 Requirements for PoDL
    4. 2.4 Clocking
      1. 2.4.1 Topology 1
      2. 2.4.2 Topology 2
  6. 3Summary
  7. 4References

2 Power Supply

A very important aspect when looking at EMI is the power supply. The goal is to minimize noise on every supply rail for two reasons, noise can interfere with your circuit and causes ICs to not work properly, possibly even receiving brown outs, but also your supply line can bring the noise to the environment either by radiating (radiated emissions) or through wires (conducted emissions).

When looking at a typical block diagram of the power tree of a system, we can separate into the internal supply rails, for example all voltages going to processors, Ethernet Phys and everything that powers the system from external supply inputs. In Figure 2-1 these are the 24 V PoDL and 24 V Aux.

GUID-20231108-SS0I-GFJP-4WSR-MV6PJWBFX4HL-low.svgFigure 2-1 Power Supply Block Diagram