Thermaltake Toughpower XT 775 W Power Supply Review
Secondary Analysis
Contents
The secondary from the new Toughpower XT models is different in two aspects. First, as mentioned, it uses a DC-DC design, meaning that the power supply is basically a +12 V unit with the +5 V and +3.3 V outputs being produced by two small switching power supplies attached to the +12 V output. And the main +12 V rail uses a synchronous design, name given when the rectifiers are replaced with MOSFET transistors in order to increase efficiency.
Five IPP057N08N3 power MOSFET are used on the main +12 V rail, three in charge of the direct rectification and two in charge of the “freewheeling” part of the rectification. Each transistor can deliver up to 80 A at 100° C in continuous mode, or up to 320 A at 25° C in pulse mode, with an RDS(on) of 5.4 mΩ, which is extremely low (which is great, the lower this number, the higher efficiency is).
Figure 13: +12 V transistors.
The +5 V and +3.3 V outputs are produced by two small printed circuit boards that are attached to the main +12 V rail. Each board features a small switch-mode power supply based on an APW7073 PWM controller and four ME90N03 MOSFETs, each one capable of handling up to 60 A at 25° C or 47 A at 70° C in continuous mode, or up to 240 A at 25° C in pulse mode, with a maximum RDS(on) of 9 mΩ. Each board has five solid caps.
Figure 14: One of the two DC-DC converters.
This power supply uses a PS229 monitoring integrated circuit, which is in charge of the power supply protections. Unfortunately there is no information about this circuit on the manufacturer’s website.
Figure 16: Monitoring circuit.
Electrolytic capacitors from the secondary are Taiwanese from Teapo. Unfortunately Thermaltake says that this unit has “Japanese capacitors” (plural), which isn’t true; only the main electrolytic capacitor from the primary is Japanese. We’ve seen this happen before on some Seventeam power supplies and the problem was the translation from Chinese to English.