On this page we will take an in-depth look at the primary stage of Rosewill Green Series 630 W. For a better understanding, please read our Anatomy of Switching Power Supplies tutorial.

This power supply uses one GBU806 rectifying bridge in its primary, which can deliver up to 8 A at 100º C if a heatsink is used, which is the case (without a heatsink the current limit drops to 3.2 A). At 115 V this unit would be able to pull up to 920 W from the power grid; assuming 80% efficiency, the bridge would allow this unit to deliver up to 736 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.

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Figure 9: Rectifying bridge.

On the active PFC circuit two SPW20N60C3 power MOSFET transistors are used, each one capable of delivering up to 20.7 A at 25º C or 13.1 A at 100º C in continuous mode (note the difference temperature makes), or up to 62.1 A in pulse mode at 25º C. These transistors present a resistance of 190 mΩ when turned on, a characteristic called RDS(on). This number indicates the amount of power that is wasted, so the lower this number the better, as less power will be wasted thus increasing efficiency.

This power supply uses a Taiwanese capacitor from Teapo labeled at 85º C to filter the output from the active PFC circuit.

In the switching section, another two SPW20N60C3 power MOSFET transistors are used on the traditional two-transistor forward configuration.

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Figure 10: +5VSB switching transistor, one of the active PFC transistors and the two switching transistors.

The primary is controlled by a CM6800 PFC/PWM combo controller.

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Figure 11: PFC/PWM combo controller.

Now let’s take a look at the secondary of this power supply.