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 Seasonic's new Titanium platform. It took them some time to build since they had to deliver something capable enough to beat the performance of Super Flower's Leadex platform. The design looks similar to that of previous Seasonic offerings, but upon taking a closer look, we spotted several changes that upgrade efficiency and overall performance. What strikes us as kind of odd, though, is the absence of a bridge-less APFC converter. Seasonic's engineers apparently managed to meet the strict 80 PLUS Titanium requirements without FETs taking the place of bridge rectifiers. This looks to be possible with lower-wattage units, but as capacity increases, losses on bridge rectifiers are significant, which would most likely make a bridge-less design the way to go.

The primary side of the Titanium Prime includes a full-bridge topology and an LLC resonant converter, and it is worth mentioning that the two bulk caps in the APFC converter have a very high combined capacity. Seasonic sought to offer the longest possible hold-up time by including these, although their high capacity will to a degree affect the unit's efficiency, especially under high loads. A synchronous design with VRMs for the generation of the minor rails is used in the secondary side. The design is completely devoid of power cables, which would not only restrict internal airflow but cause notable power losses as the load increases. This is also the first high-end Seasonic platform with a fan that is larger than 120mm, which is a must in such a PSU to keep noise output low.


The transient filter starts at the AC receptacle with two X and two Y caps. It continues as per usual on the main PCB with four more Y caps, an additional X cap, two CM chokes, and an MOV. The filter is complete and does a fantastic job, as you will figure out by looking at the results of our EMI measurements.


Spade terminals are used to connect the main power cables to the PSU's mainboard. These also minimized how much desoldering had to take place for this review.


A couple Vishay LVB2560s capable of handling up to 50 A of current combined are this unit's bridge rectifiers. They are too powerful for the PSU's 750 W capacity, but look to be highly efficient or Seasonic would have used different parts here.


Inrush current protection is provided by an NTC thermistor that is supported by a bypass relay. The latter not only increases efficiency, but allows the thermistor to cool down quickly while the PSU is in operation.


The APFC converter uses two Infineon IPP50R140CP FETs and a single SCS110AG boost diode. The PFC controller is a NPC1654 IC by ON Semiconductor, installed on a small vertical board that is covered by Mylar tape. There are also a couple parallel bulk caps by Chemi-Con with a very high combined capacity of 1100uF for a 750 W PSU.


The primary FETs are arranged in a full-bridge topology, and their model number is IPP50R199CP; their manufacturer is Infineon. An LLC resonant converter increases efficiency through (almost) loss-less switching, and the resonant controller is a Champion CM6901 IC, which a lot of highly efficient PSUs use. A couple Silicon Labs Si8230BD ICs installed on the solder side of the PCB are the driving ICs for the primary FETs.


The small heatsink out of two parts in the secondary side is empty of components. It is actually there to help with the cooling of the four Fairchild FDMS015N04B FETs on the obverse side of the PCB. Those FETs are mostly cooled by the chassis they come in touch with through a large thermal pad. Under the heatsink mentioned above are a series of polymer caps by FPCAP. These filter the +12V output. FPCAP belongs to Nichicon and enjoys a very good reputation.


Both VRMs that handle the minor rails are on the same board. In total, six Infineon BSC0906NS FETs are used by those rails, and their common PWM controller is an ANPEC APW7159 IC.


All filtering caps, both polymer and electrolytic, are of high quality. The electrolytic caps are mostly by Chemi-Con (105°C, KZE, KZH), with only one sourced by Rubycon (105°C, YXD). The latter is used in the 5VSB circuit. The polymer caps are provided by Chemi-Con and FPCAP.


A small board in the secondary side houses a Lite-On LSP5523 buck converter that most likely handles the -12V rail.


The 5VSB rail uses a Leadtrend LD7750R PWM controller Seasonic installed onto the solder side of the main PCB. The same rail also uses a STU6N65K3 FET provided by STMicroelectronics. On the solder side of the main PCB is a single Infineon BSC0906NS FET, which we believe the 5VSB rail utilizes.


A large board in the secondary side hosts the parts responsible for the platform's housekeeping, namely a Weltrend WT7527V and an AS393 dual-voltage comparator. The WT7257V supports OCP for up to two virtual +12V rails, but the SSR-750TD only has one.


A number of FPCAP and Chemi-Con polymer caps and two electrolytic caps filter the rails at the front of the modular board. The rear of the board is covered by a plastic shield.


Soldering quality is pretty good, although not top-notch. As the production line matures, soldering quality will probably get better still.


The cooling fan is provided by Hong Hua, and its model number is HA13525M12F-Z. This fan uses a fluid dynamic bearing for better longevity. Seasonic mentions that this fan will last 70,000 hours at 40 °C, so it should last a long time, especially if you consider the PSU's long-lasting passive mode. At high speeds, this fan is loud, there is no doubt about that. However, its profile is very loose, so you will barely hear it even if you deactivate semi-passive mode.