On this page we will take an in-depth look at the primary stage of Antec TruePower New 750 W. For a better understanding, please read our Anatomy of Switching Power Supplies tutorial.

This power supply uses two GBU806 rectifying bridges connected in parallel, each one being able to deliver up to 8 A at 100º C. These components are clearly overspec’ed: at 115 V this unit would be able to pull up to 1,840 W from the power grid; assuming 80% efficiency, the bridges would allow this unit to deliver up to 1,472 W without burning these components. 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 10: Rectifying bridges.

On the active PFC circuit two SPW35N60C3 power MOSFET transistors are used, each one capable of delivering up to 34.6 A at 25º C or 21.9 A at 100º C in continuous mode (note the difference temperature makes), or up to 103.8 A in pulse mode at 25º C. These transistors present a maximum resistance of 100 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.

The primary electrolytic capacitor is Japanese from Chemi-Con, which is always nice to see, and labeled at 85º C.

In the switching section, two SPP24N60C3 power MOSFET transistors are used on the traditional two-transistor forward configuration, each one capable of delivering up to 24.3 A at 25º C or up to 15.4 A at 100º C in continuous mode, or up to 72.9 A at 25º C in pulse mode, presenting an RDS(on) of 160 mΩ.

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Figure 11: Switching transistors and active PFC transistor.

The primary is controlled by a CM6802 PFC/PWM combo controller.

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Figure 12: PFC/PWM combo controller.

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