Let’s now take an in-depth look on the primary stage from AcBel Polytech iPoer 660. For a better understanding, please read our Anatomy of Switching Power Supplies tutorial.
This power supply uses two GBU605 rectifying bridges connected in parallel on its primary, each one supporting up to 6 A at 100º C, so the rectifying section can handle up to 12 A at 100º C. The bridges aren’t attached to a heatsink.
click to enlarge Figure 8: Rectifying bridges.
The active PFC circuit uses two FCPF11N60 power MOSFET transistors, which one capable of handling up to 7 A in continuous mode at 100º C (or 11 A at 25º C; see the difference temperature makes) or 33 A in pulse mode at 25º C. These transistors are located on the same heatsink as the switching transistors.
On the switching section this power supply uses another two FCPF11N60 power MOSFET transistors in the traditional two-transistor forward configuration.
click to enlarge Figure 9: Active PFC transistor (left) and switching transistor (right).
The primary section of this power supply is controlled by a FAN4800 integrated circuit, which is a PFC/PWM controller combo.
click to enlarge Figure 10: Active PFC/PWM controller combo.
