OCZ ZS Series 650 W Power Supply Review

Primary Analysis

On this page we will take an in-depth look at the primary stage of the OCZ ZS Series 650 W. For a better understanding, please read our Anatomy of Switching Power Supplies tutorial.

This power supply uses two GBU805 rectifying bridges, attached to an individual heatsink. These components support up to 8 A at 100° C each, so in theory, you would be able to pull up to 1,840 W from a 115 V power grid. Assuming 80% efficiency, the bridges would allow this unit to deliver up to 1,472 W without burning themselves out. Of course, we are only talking about these particular components. The real limit will depend on all the components combined in this power supply.

Figure 10: Rectifying bridges

The active PFC circuit uses two IPW60R190C6 MOSFETs, each supporting up to 20.2 A at 25° C or 12.8 A at 100° C in continuous mode (note the difference temperature makes), or 59 A at 25° C in pulse mode. These transistors present a 190 mΩ resistance when turned on, a characteristic called RDS(on). The lower the number t
he better, meaning that the transistor will waste less power, and the power supply will have a higher efficiency.

Figure 11: Active PFC diode and transistors

The electrolytic capacitor that filters the output of the active PFC circuit is Japanese, from Matsushita (Panasonic), and labeled at 85° C.

In the switching section, two SPP20N60C3 MOSFETs are used in the traditional two-transistor forward configuration. Each transistor supports up to 20.7 A at 25° C or 13.1 A at 100° C in continuous mode, or 62.1 A at 25° C in pulse mode, with an RDS(on) of 190 mΩ.

Figure 12: Switching transistors

The primary is controlled by the popular CM6800 active PFC/PWM combo controller.

Figure 13: Active PFC/PWM combo controller

Let’s now take a look at the secondary of this power supply.