Seasonic PRIME TX-1300 1300W Report (Page 3 of 4)

Page 3 - Physical Look - Inside

As always, we opened up our Seasonic PRIME TX-1300 1300W power supply to take a detailed look at what is going on inside. Please note that doing this at home will void your 12-year warranty, thanks to the warranty seal Seasonic applied over one of the attachment screws. It is great it comes with a 12-year warranty, which is a little longer than the industry standard of 10 years for performance PSUs. For the benefit of you, we cracked ours open, so you do not need to. There are no user serviceable parts inside.

Opening the Seasonic PRIME TX-1300 1300W is quite straightforward with the removal of four screws. For some reason, one side of the shell was super tight, so I had to really pry to get it out. Taking out the internal components from the enclosure requires the removal of more.

Our photo above shows an overhead view of its internal components. Its OEM is Seasonic themselves, which should be to nobody’s surprise. It features an LLC full bridge topology with bridgeless interleave PFC on the primary side and DC-to-DC converters on the secondary side. At first glance, the build quality appears to be excellent. There are four main heatsinks inside and almost no wires. They are finned and of various sizes, as you can see in our photo above.

Pulling the enclosure apart and we got straight to the internal inspection. The transient filter stage is the first input stage of a computer power supply, so we will take a look at that first. Seasonic has always done a great job in the past to make sure all their power supplies met or exceeded the recommended requirements, and the PRIME TX-1300 1300W is no exception. The Seasonic PRIME TX-1300 1300W has one metal oxide varistor, two metalized polyester X-capacitors, six ceramic Y-capacitors, and two common mode chokes. This is two times the number of X capacitors and three times the number of Y capacitors than recommended. Considering some PSUs have missing MOVs, I am happy to see it here as this component is used to stabilize spikes from the AC line.

The active PFC circuit featured on the Seasonic PRIME TX-1300 1300W is a bridgeless boost interleaved design. A bridgeless boost interleaved design is more of a traditional approach for maximum efficiency, but more exotic designs nowadays feature bridgeless totem-pole PFC thanks to new semiconductor materials for power switches. The standby circuit still features a Shindengen LL25XB60 bridge diode. Four Infineon rectifier MOSFETs are used. Unfortunately, I was not able to see the specific model number for these rectifier MOSFETs.

Further down the line, on the heatsink closest to the outer edge, there are two Infineon IDH08G65C6 silicon carbide Schottky diodes as the APFC boost diode attached to it. On the same heatsink, there are four Infineon IPA60R125P6 power transistors attached to it. Each is certified for up to 19A at 100c. These transistors present a maximum resistance of 125 mΩ and typical resistance of 113 mΩ at 25c when turned on according to the manufacturer's data sheet. This on characteristic is called Static Drain-Source On-Resistance, or commonly abbreviated as RDS(on). The more efficient the component is, the lower the RDS(on) value, since it wastes less power with lower resistance.

On the smaller heatsink adjacent to the bulk capacitors, we can see four more Infineon IPA60R125P6 power MOSFETs as the main switchers. Texas Instruments' UCD28070 is the PFC controller, located on the vertical board perpendicular to the rear connector board. The Champion CM6901T2X resonant controller and a pair of Silicon Labs Si8233BD driver ICs are part of the APFC controller circuit, located at the back of the main board.

On the primary side, we can see three Japanese brand Nippon Chemi-Con capacitors. 100% Japanese brand capacitors are specified on the marketing material, so this is to be expected. Our 1300W version of Seasonic's latest PRIME TX series power supply incorporates three 680µF x 420V capacitors in parallel for an equivalent capacitance of 2040µF x 420V. It is rated at 105c, whereas more value-oriented power supplies usually use 85c rated capacitors.

On the secondary side, we can see more Japanese brand electrolytic capacitors from Nippon Chemi-Con rated at 105c. As with modern high efficiency power supplies, all rectifiers produce the +12V out, while the +5V and +3.3V outputs are generated from the +12V output using a DC-to-DC converter within the power supply unit. Eight Nexperia PSMN1R0-40YLD MOSFETs are responsible for generating the +12V output, located at the back of the main board. The PSMN1R0-40YLD's rated continuous drain current is 198A at 100c. It has an RDS(on) value of 1.1 mΩ maximum and 0.93 mΩ typical at 10V.

On the vertical board perpendicular to the rear connector board, we can spot a Weltrend WT7527RA monitoring IC for over/under current and over/under voltage protection and a Weltrend WT51F104 fan controller. A Power Integrations INN3164C standby PWM controller is located at the back of the main board. The datasheets for all components mentioned in this review can be found on their respective manufacturers' websites.

At the back, we have a large daughterboard covering the majority of the rear panel for the modular cable sockets. All modular sockets at the bottom are soldered directly to the main PCB after the secondary stage. Pin headers join the mainboard and daughterboard to reduce power transmission loss. The output connector configuration can be seen on the previous page. Overall, the internal build quality of Seasonic's PRIME TX-1300 1300W power supply is practically second to none -- nothing short of what we would expect from a flagship product from the company. Components are arranged beautifully for optimal cooling with almost no wires running around inside, and solder points on its black/green PCB is quite clean in general. I would say the Seasonic-branded, Seasonic-built PRIME TX-1300 1300W is simply excellent with regards to the selection of components used under the hood.

Lastly, we see a 135mm fan that provides cooling to the Seasonic PRIME TX-1300 1300W's internal components. It is connected to an add-in board using a 4-pin connector. A 135mm fan is only marginally smaller than the 140mm maximum you can fit in an ATX power supply, and it is beneficial in most cases in providing lots of airflow at lower speeds for quiet operation. The model of the fan is Hong Hua HA13525H12SF-Z, as shown in our photo above. The HA13525H12SF-Z is a fluid dynamic bearing fan specified at 0.50A for a maximum speed of 2300 RPM. The fan is not supposed to activate until the PSU is loaded to approximately 520W with Hybrid Mode active. As such, it should remain off for the most part, and even when it is on, Seasonic uses a silent speed profile, so noise is not going to be a problem at all. Fans with fluid dynamic bearings generally have much longer lifespans compared to sleeve bearing fans and is quite suitable for this application.

Page Index
1. Introduction, Packaging, Specifications
2. Physical Look - Outside
3. Physical Look - Inside
4. Minor Tests and Conclusion