Corsair AX760i Power Supply Review

Primary Analysis

On this page, we will take an in-depth look at the primary stage of the Corsair AX760i. For a better understanding, please read our “Anatomy of Switching Power Supplies” tutorial.        

This power supply uses a GSIB2560L rectifying bridge, which is attached to an individual heatsink. This bridge supports up to 25 A at 98° C. In theory, you would be able to pull up to 2,875 W from a 115 V power grid. Assuming 80% efficiency, the bridge would allow this unit to deliver up to 2,300 W without burning itself out (or 2,588 W at 90% efficiency). Of course, we are only talking about this particular component. The real limit will depend on all the components combined in this power supply.

Figure 12: Rectifying bridge

The active PFC circuit uses two IPP60R199CP MOSFETs, each one supporting up to 16 A at 25° C or 10 A at 100° C in continuous mode (note the difference temperature makes), or 51 A at 25° C in pulse mode. These transistors present a 199 mΩ maximum resistance when turned on, a characteristic called RDS(on). The lower the number the better, meaning that the transistor will waste less power, and the power supply will have a higher efficiency.

Figure 13: The two active PFC transistors and the active PFC diode

The output of the active PFC circuit is filtered by one 560 µF x 420 V Japanese electrolytic capacitor, from Chemi-Con, labeled at 105° C.

Figure 14: Capacitor

In the switching section, two IPP60R125C6 MOSFETs are employed using a resonant configuration. Each transistor supports up to 30 A at 25° C or 19 A at 100° C in continuous mode or up to 89 A at 25° C in pulse mode, with a maximum RDS(on) of 125 mΩ. 

Figure 15: The two switching transistors

The active PFC circuit and the switching transistors are controlled by the digital signal processor (DSP) that is the heart of this power supply. The DSP used is a Freescale MC56F8014. Other chips worth mentioning are the C8051F310 and the C8051F380, which are beefed-up versions of the popular 8051 microcontroller. The C8051F310 has an analog-to-digital converter (ADC), and the C8051F380 has a USB interface, which is used by the Corsair Link connection.

Figure 16: The digital signal processor board

Figure 17: The digital signal processor board

The +5VSB power supply is located on a separate printed circuit board.

Figure 18: The +5VSB power supply

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