SMPS Topologies Overview¶
Non-isolated¶
Isolated¶
Push-Pull¶
- MOSFETs are required to
Half-Bridge¶
Facts¶
- Voltage applied to the primary is half the rectified and smoothed input voltage. So, for 230V main, the primary voltage will be about 162V peak or 325V peak-to-peak.
- SMPS can be built to output up to 500 watts normally. However, it can be increased up to 650-750 watts if front-end PFC is used.1
- Power is transferred by normal transformer action.
Cons¶
- Secondary winding require more turns, increasing copper loss.
Power Rating Considerations¶
| 0-100 W, Iout<10 A |
0-100 W, Iout>10 A |
100-400 W | 400-1200 W | 1200-3000 W | |
|---|---|---|---|---|---|
| Single-switch flyback | ✔ | ||||
| 2-switch flyback | ✔ | ||||
| Active clamp flyback | ✔ | ||||
| Single-switch forward | ✔ | ✔ | |||
| 2-switch forward | ✔ | ✔ | ✔ | ||
| Active clamp forward | ✔ | ✔ | ✔ | ||
| Half bridge | ✔ | ✔ | ✔1 | ||
| LLC Half Bridge | ✔ | ✔ | ✔ | ||
| Full bridge | ✔ | ||||
| Phase shifted ZVT full bridge | ✔ | ✔ |
-
Half-bridge topology is best suited for applications up to 500 watts. However it can be increased up to 650-750 watts if front-end PFC is used. Ref: Microchip AN1114: Switch Mode Power Supply (SMPS) Topologies (Part I), page 21 ↩↩