Corsair AX860i 860 W

Corsair AX860i 860 W

Voltage Regulation, Hold-up Time & Inrush Current »

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 better.


All AXi PSUs are made by Flextronics: a company that currently only builds desktop PSUs for Corsair and one that easily manages to compete with its highly experienced competition in the high-end category. This unit does, similar to the AX760i and the flagship AX1200i, control the APFC circuit, the main switchers, the DC-DC converters of the minor rails, and the protections features through a Digital Signal Processor or DSP. The advantage of digital control is a very fast response time, a tight control, and the fact that it, compared to conventional controllers, takes into account many more parameters. The DSP of the AX860i also features an LLC resonant converter for increased efficiency and a synchronous design on the primary side, and VRMs for the generation of the minor rails on the secondary side.


The transient filter starts right at the AC receptacle with two Y caps. This time around, Corsair chose not to use a complete EMI line filter, like in the AX1200i, because of space restrictions and increased costs. We find more transient filter components, namely six Y caps, two X caps, two CM chokes, and an MOV, on the main PCB.


The bridge rectifier, a GSIB 2560L, uses its own heatsink. Exactly the same is used in the AX760i.


In the APFC, both mosfets and the boost diode are fully covered by metal shields that reduce EMI, which meant that we were unable to identify them since we didn't want to use the Hakko on this fine PCB. The single, huge, hold-up cap (420V, 680μF) is provided by Matsushita/Panasonic and is rated at up to 105°C. This is one of the main differences to the AX760i; it uses a smaller 560μF capacity hold-cap provided by Nippon Chemi-Con here.


The PSU uses an NTC thermistor for protection against large inrush-currents. There is also an electromagnetic relay that bypasses the thermistor once the start-up phase finishes, which wastes less energy and allows it to cool down quickly.


The main switchers are covered by metal shields. We find the resonant converter that provides a significant efficiency boost in front of these switchers.


This is the control PCB. It uses the same components as the AX760i. A 56F8014 Freescale DSC (Digital Signal Controller) is the main controller and includes five PWM outputs along with two 12-bit Analog-to-Digital Converters (ADCs) that can be programmed using the C programming language. Above the 56F8014 DSC, we find an LM2902K quadruple operational amplifier and, to its left, four optocouplers that provide the necessary isolation.


In the middle of the PCB, we find two fully integrated Silicon Lab mixed-signal System-on-a-Chip MCUs that also play the role of a DSP with higher clock speeds. Their model numbers are C8051F310 and C8051F380. The latter MCU includes a USB 2.0 function-controller through which the PSU sends and receives data from the Corsair Link software. There are also three more LM2902K quadruple operational amplifiers on the left side of the PCB.


This is the 5V DC-DC converter. On it, four IPD050N03L fets are installed.


The +12V main filtering caps are a group of polymer CapXons and are located right next to the main transformer. Of course, Japanese caps would be highly preferred here instead of the CapXons, but Corsair must have been very confident, or they wouldn't have used them in their flagship PSU that is covered by a hefty seven-year warranty. Above the aforementioned caps is a metal bar which passes the +12V rail to the modular PCB with the help of several thick wires. Some ferrite rings are used to suppress EMI.


The 3.3V DC-DC converter resides between the modular PCB and the metal bar.


The 5VSB rail is generated by the components of a small daughter-board located on the secondary side. We spotted a Rubycon electrolytic cap right next to it. Most electrolytic caps on the secondary side are provided by the for its high-quality products legendary Rubycon.


Soldering quality is very good and the design is really clean. An Infineon ICE2HS01G resonant controller and a high-voltage L6385E high and low-side driver are soldered onto this side.


We find many small Sanyo polymer caps that provide some extra ripple-filtering and two electrolytic caps from Rubycon and Nippon Chemi-Con on the front side of the PCB.


The cooling fan is provided by Yate Loon and its model number is D12BH-12 (12 V, 0.3 A, 2300 RPM, 89 CFM, 41 dBA). It uses ball-bearings for increased lifetime and is quite audible at high RPM. The fan profile is, thankfully, very relaxed, which means that the fan will not spin up at all during lower loads.
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