Secondary Analysis
Contents
On this page we will take an in-depth look at the primary stage of the Antec EarthWatts Platinum 650 W. For a better understanding, please read our “Anatomy of Switching Power Supplies” tutorial.
This power supply uses one GBU15L06 rectifying bridge, which is attached to an individual heatsink. This bridge supports up to 15 A at 115° C, so in theory, you would be able to pull up to 1,725 W from a 115 V power grid. Assuming 80% efficiency, the bridge would allow this unit to deliver up to 1,380 W without burning itself out. 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 10: Rectifying bridge
The active PFC circuit uses two IPA60R125CP MOSFETs, each one capable of delivering up to 25 A at 25° C or 16 A at 100° C in continuous mode (note the difference temperature makes), or up to 82 A in pulse mode at 25° C. These transistors present a 125 mΩ resistance when turned on, a characteristic called RDS(on). The lower this number the better, meaning that the transistors will waste less power, and the power supply will achieve a higher efficiency.
The output of the active PFC circuit is filtered by a 390 µF x 420 V electrolytic capacitor from CapXon and labeled at 85° C.
In the switching section, the Antec EarthWatts Platinum 650 W uses the same unique design adopted by FSP on their 80 Plus Gold power supplies, called active clamp reset forward. The switching transistor is an SPA17N80C3 MOSFET, which is capable of delivering up to 17 A at 25° C or 11 A at 100° C in continuous mode (note the difference temperature makes), or up to 51 A at 25° C in pulse mode. This transistor presents a 290 mΩ RDS(on). A second transistor (resetting transistor) is used to turn off the switching transistor and is controlled from the secondary side. The transistor used for this function is an FQPF3N80C. This is exactly the same configuration used in the FSP Aurum Gold 700 W and the FSP Aurum CM Gold 750 W.
Figure 11: Switching transistors and active PFC transistors
The primary is managed by a custom-made PFC/PWM controller called FSP6600. Since this is a custom integrated circuit, no datasheet is available for it.
Figure 12: Active PFC/PWM controller
Let’s now take a look at the secondary of this power supply.