SDAA139 October 2025 UCC33020 , UCC33020-Q1 , UCC33410 , UCC33410-Q1 , UCC33411-Q1 , UCC33420 , UCC33420-Q1 , UCC33421-Q1
2.4 Damping RC Network
For CE, the DUT is powered by a power supply through the LISNs. The LISNs have a 50μH inductance that must be dampened such that the output impedance after the LISNs is not higher than the input impedance of the DC/DC converter. For this reason, an RC damping network is used at the input of UCC33420-Q1 after the LISN. In a real system, if UCC33420-Q1 has a pre-regulator at the input side that decouples the power supply from the LISNs, the RC damping network is not needed. Figure 2-10 and Figure 2-11 show the damping network schematic and layout.
Figure 2-10 RC Network Schematic
Figure 2-11 RC Network in the layout