OCZ Z Series 1000 W Power Supply Review

Secondary Analysis

This power supply is based on a DC-DC design, meaning that it is basically a +12 V power supply with the +5 V and +3.3 V outputs being generated using two separated switching power supplies connected to the +12 V rail. This design is proving to be the best choice in order to achieve high efficiency. On top of that OCZ Z Series uses a synchronous design to generate its +12 V output. In this kind of design the rectifiers are replaced with MOSFET transistors in order to increase efficiency.

Eight AP95T07GP MOSFETs are used to produce the +12 V rail, four for the direct rectification and four for the “freewheeling” part. Each one supports up to 80 A at 25° C or 70 A at 100° C in continuous mode, or up to 320 A at 25° C in pulse mode, with an RDS(on) of only 5 mΩ. This is exactly the same configuration used on the 850 W model.

The maximum theoretical current each line can deliver is given by the formula I / (1 – D), where D is the duty cycle used and I is the maximum current supported by the rectifying diode. Just as an exercise, we can assume a typical duty cycle of 30%.

The +12 V rail is also used by the +5 V and +3.3 V rails as well; if all power was pulled from the +12 V rail alone, we are talking about a maximum theoretical current of 400 A or 4,800 W at 100° C. Holy moly!

Of course this is a theoretical number and we are just making an exercise here. The real amount of current/power each output can deliver is limited by other components.

Figure 13: +12 V transistors.

In Figure 14, you can see one of the DC-DC modules (the unit has one for the +5 V output and one for +3.3 V output). It has four IPD060N03L MOSFET transistors – each one capable of handling up to 50 A at 100° C with a 6 mΩ RDS(on) – and one APW7073 PWM controller. These modules are identical to the ones used on the 850 W version of this power supply.

Figure 14: DC-DC conversion module.

The outputs are monitored by a PS224 integrated circuit, which supports OVP (over voltage protection), UVP (under voltage protection) and OCP (over current protection). Any other protection this power supply may have is implemented outside this circuit.

Figure 15: Monitoring circuit.

All capacitors from the secondary are also Japanese, from Chemi-Con.