Primary Analysis
Contents
On this page we will take an in-depth look at the primary stage of the Thermaltake Smart 730 W. For a better understanding, please read our “Anatomy of Switching Power Supplies” tutorial.
This power supply uses one GBJ1506 rectifying bridge, which is attached to the same heatsink as the active PFC transistors and diode. This bridge supports up to 15 A at 100° 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 delive
r 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. The 630 W model uses a 10 A bridge.
Figure 10: Rectifying bridge
The active PFC circuit uses three IPP60R190C6 MOSFETs, each one capable of delivering up to 20.2 A at 25° C or 12.8 A at 100° C in continuous mode (note the difference temperature makes), or up to 59 A in pulse mode at 25° C. These transistors present a 190 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 630 W model uses two of these transistors.
Figure 11: Active PFC transistors and diode
The output of the active PFC circuit is filtered by a 470 µF x 400 V electrolytic capacitor from Teapo and labeled at 85° C. The 630 W model uses a 330 µF x 400 V capacitor here.
In the switching section, another two IPP60R190C6 MOSFETs are used in the traditional two-transistor forward configuration. The specifications for these transistors were already discussed above. The 630 W model uses different (“weaker”) transistors here.
Figure 12: One of the switching transistors
The primary is managed by a FAN4800I active PFC/PWM controller.
Figure 13: Active PFC/PWM controller
Let’s now take a look at the secondary of this power supply.
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