SDAA139 October 2025 UCC33020 , UCC33020-Q1 , UCC33410 , UCC33410-Q1 , UCC33411-Q1 , UCC33420 , UCC33420-Q1 , UCC33421-Q1
2.2 EMI FIlter
A pi filter was used to mitigate the burst frequency harmonics in the 100-500kHz range. A 2.2μH DM inductor with two 22μF capacitors on each side are selected. The DM inductor is fully shielded to minimize coupling coming from the H-field of the transformer. Table 2-1 shows the DM inductor selection depending on power level. The CE results for UCC33420-Q1 5V/5V, Pout=1.5W are shown in Figure 2-5.
Figure 2-4 UCC33420-Q1 EMI Filter
Figure 2-5 UCC33420 5V/5V Pout=1.5W CETable 2-1 DM Inductor selection
| Power level | DM Inductor |
|---|---|
| 0.5W | 2.2uH, 0603, 800mA, PN:74479763222 |
| 1W, 1.5W | 2.2uH, 0805, 2.1A, PN: 74479275222 |