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 is the new Seasonic XP2S platform, which is among the best non-digital PSU platforms money can buy today. Although it is analogue controlled, it offers performance similar to current high-end digital designs. We are met by a full-bridge topology with an LLC resonant converter in the primary side, and the secondary side uses a synchronous design with two DC-DC converters to generate the minor rails.


The sealed PCB behind the AC receptacle hosts two Y caps, a single X cap, and a CM choke. The second part of the EMI filter on the main PCB includes two X and two Y caps, a CM and DM choke, and an MOV (Metal Oxide Varistor). There is obviously an NTC thermistor to protect the unit against large inrush currents, and an electromagnetic relay isolates it once the start-up phase finishes.


Both bridge rectifiers (GBJ1506) are bolted onto a dedicated heatsink.


The APFC converter uses two Infineon IPP60R199CP (650V, 10A @ 100°C, 0.199Ohm) fets and a single SiC SCS106AG (600V, 6A @ 25°C) boost diode. The APFC controller is installed onto a small daughter-board and is the same as in the Snow Silent-1050. It is by ON Semiconductor, and its model number is NPC1654.


Four IPP50R250CP (550V, 9A @ 100°C, 0.25Ohm) fets in a full-bridge topology act as the primary switchers. They are backed by an LLC resonant converter for lower switching losses.


The +12V rail is regulated by several fets on a vertical daughter-board. These fets are cooled by two heatsinks that are held together by two screws. Seasonic unfortunately didn't use any heat conductive paste with these heatsinks. The LLC resonant controller is a Champion CM6901 IC, all electrolytic caps in the secondary side are by Chemi-Con, and the polymer caps are by FPCAP.


Both DC-DC converters are on the modular PCB to reduce energy losses. Each of these uses three Infineon BSC0901NS fets, and their common PWM controller is an Anpec APW7159.


The standby PWM controller is an Infineon ICE2QR4765 IC.


A vertical PCB in the secondary side hosts the protections IC, a Weltrend WT7257V, and an AS393 dual voltage comparator. The WT7257V supports OCP for up to two +12V rails; however, this PSU only has one.


The soldering quality on the main PCB is very good.


Seasonic uses FDB fans by Hong Hua for their Snow Silent units, and this particular fan's model number is HA1225M12F-Z (12 V, 0.45 A, 2050 RPM). FDB fans are currently considered among the best money can buy since they operate quietly and last for a very long time, much longer than ball-bearing fans. This is a moderately fast FDB fan with a very long passive phase in semi-passive mode, and its relaxed fan profile will allow it to operate very quietly throughout.