A Look Inside

Before reading this page, we strongly suggest a look at this article, which will help you understand much better the internal components of a PSU.


The OEM of this unit is ETASIS, a highly respectable manufacturer that mainly makes server units. They haven't released a desktop PSU in many years now. Nevertheless, their experience in making server grade PSUs, combined with EVGA's experience in the enthusiast market, makes for a very strong team. The NEX1500 uses a modern platform with an interleaved PFC converter and a ZVS phase shift full bridge topology on the primary side, while on the secondary side, the +12V fets are attached directly to the uniquely designed main transformer, with the minor rails being generated by two DC-DC converters. The PSU also utilizes a Digital Signal Processor, or DSP, to control the +12V rectification as well as the PSU's protection features. The main PCB, according to EVGA, consists of four layers, while the modular one has six layers.


You have to dive deep into the unit's internals in order to remove the handle bar (in case you don't like it).


The transient filtering stages start right at the AC receptacle and consist of one X and two Y caps. On the main PCB, we find many more components, including four X and two pairs of Y caps, with the second pair installed after the bridge rectifiers, two CM chokes, and an MOV. There is also an electromagnetic relay, along with a thermistor, responsible for protection against large inrush currents.


The two parallel bridge rectifiers (GBU2506) are bolted onto a quite large, dedicated heatsink and can handle up to 50 A of current combined!


In the APFC section, we find a 2-phase interleaved CCM (Continuous Conduction Mode) topology, in which two smaller CCM PFC converters work out of phase, something that reduces the input and output ripple current, along with the current stress on the PFC fets while also increasing efficiency slightly. Each CCM converter uses two Infineon SPW47N60C3 fets and two CREE C3D10060 boost diodes. As hold up caps, two parallel Hitachi caps are used (470μF each or 940μF combined, 450V, 105°C, HU series).


The main switchers are four Infineon SPP20N60CFD arranged into a ZVS phase shift full bridge topology. Their controller is a Texas Instruments UCC28950 IC located on a large vertical PCB on the secondary side.


All +12 V fets, twelve BSC047N08NS3, are attached to the uniquely designed main transformer in an effort to minimize energy losses and increase efficiency.


The minor rails are generated by two DC-DC converters. Between the first of the VRMs and the main transformer, we find an LM2576 step-down (buck) regulator.


Most of the filtering caps on the secondary side are electrolytic and are provided by Nippon Chemi-Con (105C, KZH and KY series). We also found some polymer ones.


The 5VSB rail is rectified by an Infineon SPP06N80C3 power transistor.


This large vertical PCB on the secondary side holds many interesting components. We will start its description from left to right. The IC you see in the second photo is an C8051F344 48-Pin Mixed-Signal MCU which, among others, includes a USB Function Controller.


In this photo, we see four ICs. The top one is an LM339A quad voltage comparator, the middle ones are two ST LMV324 operation amplifiers, and the bottom one is a MAX5401 low-drift digital potentiometer.


On the left of the UCC28950 controller, we find two UCC27324D (high speed low-side power mosfet drivers).


A series of seven TCLT1008 optocouplers provide the necessary isolation to the two circuits, housed on the same PCB.


The top IC is an ST LMV324 operation amplifier while the bottom one is a UCC28070 (two-phase interleaved CCM PFC controller).


The top IC is an LM339A quad voltage comparator, the middle one an ST LM358 dual operational amplifiers, and the bottom one is a Freescale MSE9S08SH8 MCU.


On the front of the modular PCB, we find eleven electrolytic Chemi-Con caps, along with many polymer ones that are provided by Sanyo. The modular PCB is also soldered directly onto the main one in order to minimize voltage drops and energy dissipation. Finally, soldering quality on it is simply excellent.


Once we gazed at the solder side of the main PCB, we were left speechless by its extra clean design and the impeccable soldering quality. ETASIS undoubtedly did a fine job here. One that can easily meet the corresponding Flextronics and Delta implementations eye to eye. Right before the rectify bridges, on the solder side of the PCB, we found an ACS712T Hall Effect-based current sensor, which provides information about the AC current draw of the PSU. The software utilizes this information, along with the DC power output, to calculate the efficiency of the PSU in real-time. We also spotted many current shunt resistors, which allow the measurement of current that flows on the rails of the PSU. These readings are used by the OCP circuit and the SuperNOVA software.


The cooling fan is made by Sanyo Denki and is, although it has only 120 mm diameter, powerful, since it can spin up to 4500 RPM if needed. Its model number is 9G1212P4G03 (12V, 0.90A, 51dBA, 129.94CFM). It uses ball-bearings for increased life-time and is noisy, especially at higher RPMs. It makes a hell of a noise at top speeds.