A Look Inside & Component Analysis

Before reading this page, we strongly suggest a look at this article, which will help you understand the internal components of a PSU much better. Our main tool for the disassembly of the PSU is a Thermaltronics TMT-9000S soldering and rework station. It is of extreme quality and is equipped with a matching de-soldering gun. With such equipment in hand, breaking apart every PSU is like a walk in the park!


This unit is made by Seasonic and is identical as we already stated to their SS-520FL offering. The primary side uses a full bridge topology, along with an LLC resonant converter for increased efficiency. The secondary side uses a synchronous scheme with two DC-DC converters for the generation of the minor rails. Both VRMs are directly on the modular PCB to further reduce energy losses due to excessive amounts of wiring.


Although the +12V mosfets have been moved from the main PCB's solder side to a dedicated heatsink, the enclosure plays an active role in cooling them down, and several thermal pads ensure its good contact with the PCB.


Behind the AC receptacle is a small PCB. It is protected by a metal shield for EMI suppression. Four Y caps, a CM choke, and a single X cap are installed here. All other transient filtering components are on the main PCB. These include two additional CM chokes, two X and Y caps, each, and an MOV. There is also an NTC thermistor. It protects the unit against large inrush currents, and an electromagnetic relay cuts it off the circuit once it finishes its job. Lastly, spade terminals are used on the wires transferring the load, which makes their removal an easy task.


The standby Quasi-Resonant PWM Controller is an ICE2QR4765 IC.


The parallel bridge rectifiers are two GBJ2506. They are too powerful for the needs of this unit and we cannot help but wonder why smaller ones weren't used to cut on cost.


Two Infineon IPP60R165CP fets and an STPSC606 boost diode (the SS-520FL uses a CREE C3D06060) are used in the APFC. The hold-up cap is provided by Hitachi (420V, 330µF) and is rated at 105°C, while the APFC controller, an NPC1654, is hiding on a small daughter-board between the APFC and the primary heatsink.


The main switchers, four Infineon IPP50R250CPs, are arranged in a full bridge topology, and an LLC resonant converter is utilized to provide a significant efficiency boost.


The +12V fets and LLC resonant controller, a Champion CM6901 IC, are installed on a vertical PCB in the secondary side. Two heatsinks cool the aforementioned fets, and a thermistor that has been attached to the top heatsink provides information to the OTP circuit. A series of polymer and several electrolytic caps by Nippon Chemi-Con (105°C, KZE series) filter this rail.


To reduce energy dissipation, both DC-DC converters generating the minor rails are directly on the modular PCB. Their common PWM controller is an APW7159 PWM IC, and each VRMs uses three RJK0332DPB fets. As you can see in the photos above, a heatsink has been attached to the modular panel's rear side. It provides EMI protection and plays a key role in keeping the VRMs cool.


Many polymer caps, with all being provided probably by Nippon Chemi-Con, at the front of the modular board are used for ripple-filtering purposes. Seasonic's unit uses Enesol caps here. The bottom sockets are directly soldered to the main PCB to further reduce energy losses.


The supervisor IC, a Weltrend WT7527, is installed to this PCB, along with an LM339 quad-voltage comparator. The WT7527 supports up to two virtual +12V rails, but this PSU only has one.


The main PCB's soldering quality is quite good overall, and all component leads were carefully trimmed.