SLUAAU4 June 2024 UCC28750
3 Implement SR with UCC24612-1EVM
The UCC24612-1EVM evaluation module (EVM) is used to convert the output rectifier of a flyback converter from a diode to a synchronous rectifier (SR) FET to investigate and evaluate the efficiency benefits of using an SR over a rectifier diode. The EVM comes with the UCC24612-1 SR controller installed. This controller was optimized to work with secondary side output regulated flyback converters.
The UCC28750 EVM can retrofit with UCC24612-1 EVM to improve the efficiency, and the changed items and efficiency improvement as the following shows.
Changed items
- D2 changed to UCC24612-1 EVM
- Connect the UCC24612-1 EVM TP1 to UCC28750 EVM TP5
- Connect the UCC24612-1 EVM TP2 to UCC28750 EVM TP3
- Connect the UCC24612-1 EVM TP3 to UCC28750 EVM TP4
- Change the Q1 FET to CSD19502 (100V FET)
- JP1 connected
Figure 3-1 UCC24612 EVM Schematic
Figure 3-2 Efficiency CurveTable 3-1 Efficiency Improvement
| Io (A) | Pin (Original EVM) |
Pin (D2 use SR) |
Efficiency (Original EVM) |
Efficiency (D2 use SR) |
Efficiency Improvement |
|---|---|---|---|---|---|
| 0.1 | 1.8 | 1.77 | 72.19% | 73.33% | 1.14% |
| 0.2 | 3.15 | 3.05 | 74.73% | 77.06% | 2.32% |
| 0.3 | 4.7 | 4.55 | 77% | 79.7% | 2.71% |
| 0.4 | 6.3 | 5.94 | 77.63% | 81.9% | 4.31% |
| 0.5 | 7.6 | 7.23 | 78.34% | 82.17% | 3.79% |
| 0.6 | 9 | 8.7 | 79.44% | 82.6% | 3.14% |
| 0.8 | 11.8 | 11.3 | 80.95% | 84.32% | 3.37% |
| 0.9 | 13.23 | 12.55 | 81.4% | 85.84% | 4.41% |
| 1 | 14.8 | 13.94 | 81.4% | 86.25% | 4.85% |
| 1.5 | 21.6 | 20.46 | 83% | 87.6% | 4.62% |
| 2 | 28.3 | 26.77 | 84.34% | 89.03% | 4.69% |
| 2.5 | 35.1 | 33.33 | 85.16% | 89.76% | 4.6% |
| 3 | 41.9 | 39.85 | 85.46% | 89.9% | 4.34% |
| 3.5 | 48.8 | 46.1 | 85.5% | 90.52% | 5.01% |
| 4 | 56 | 52.94 | 85.4% | 90.34% | 4.94% |
| 4.5 | 62.6 | 59.64 | 85.8% | 90.05% | 4.26% |
| 5 | 69.8 | 65.98 | 85.37% | 90.35% | 4.98% |
| 5.5 | 77.5 | 73.3 | 84.54% | 89.4% | 4.87% |
| 6 | 85.77 | 80.99 | 83.46% | 88.38% | 4.93% |