Let’s now take an in-depth look on the primary stage from GP-AL650AA. For a better understanding, please read our Anatomy of Switching Power Supplies tutorial.
This power supply uses one GBU1506 rectifying bridge on its primary, capable of delivering up to 15 A at 100º C. This component is clearly overspec'ed: at 115 V this unit would be able to pull up to 1,725 W from the power grid; assuming 80% efficiency, the bridge would allow this unit to deliver up to 1,380 W without burning this component. Of course we are only talking about this component and the real limit will depend on all other components from the power supply.
The active PFC circuit uses two STW25NM50N power MOSFET transistors. Each one is capable of handling up to 88 A @ 25º C in pulse mode (which is the case) or up to 22 A @ 25º C or 14 A @ 100º C (see the difference temperature makes).
The big electrolytic capacitor used on the primary is from OST and rated at 85º C.
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Figure 7: Active PFC transistors, active PFC diode and rectifying bridge.
The active PFC circuit is controlled by the omnipresent CM6800 PFC/PWM combo controller.
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Figure 8: Active PFC/PWM controller.
On the switching section this power supply uses another two STW25NM50N transistors, on the traditional two-transistor forward configuration. The specs for these transistors are published above.
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Figure 9: Switching transistors (the small transistor between them is for the +5VSB output).
