Corsair AX1500i Titanium PSU Review

A Look Inside And Component Analysis

Parts Description

Our main tools for disassembling PSUs are a Thermaltronics soldering and rework station and a Hakko 808 desoldering gun.

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The AX1200i and AX1500i PSUs utilize the most advanced digital platforms available on the market today. Corsair and Flextronics did an amazing job in creating a digital PSU, and the competition will have to invest lots of resources in order to keep up. To be more specific, the AX1500i uses a bridgeless design, which includes an interleaved PFC converter along with a full-bridge topology. In the secondary side, we see a synchronous design accompanied by two DC-DC converters for the generation of the minor rails. All circuits inside the AX1500i are digitally controlled, with the exception of the one that generates the 5VSB rail and most likely the circuit that handles the -12V rail as well. A Freescale MC56F8236 DSC (digital signal controller) with a couple of MCUs (microcontrollers) handles most circuits of the AX1500i, providing top performance under all conditions and Titanium efficiency.

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The AX1200i uses a server-grade, integrated EMI filter; however, the AX1500i uses only a couple of Y caps on the AC receptacle, with the rest of the EMI filtering components on the PSU's main PCB. This might look like a downgrade, but the EMI filter is more than complete, since it consists of six Y caps, five X caps, three CM chokes, a single MOV and a couple of TVS diodes. Corsair also used a significant amount of glue in order to suppress any coil-whine noise, which can become really annoying. Flextronics utilized an NTC thermistor to protect the unit from large inrush currents, and there is also an electromagnetic relay that isolates the thermistor once the start-up phase finishes.

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Instead of using bridge rectifiers for fully rectifying the incoming AC voltage, this PSU utilizes a couple of FETs that offer significantly lower energy losses. These FETs are provided by Toshiba and their model number is TK62J60W.

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This PSU uses an interleaved, two-phase PFC converter, meaning that there are in fact two APFC converters that work in parallel, with a phase difference between them. This leads to minimized input/output current ripple and lower energy losses, offering increased efficiency while at the same time doubling the effective switching frequency. The APFC stage uses four chokes, four CREE C3D06060A boost diodes and four Infineon IPA60R099 FETs. For increased heat dissipation, all FETs and diodes have optimal contact with the heat sinks, thanks to the metal clips that Flextronics used. Finally, the two parallel hold-up caps are provided by Nippon Chemi-Con (680µF and 470µF or 1150µF combined, 450V, 105°C, KMR series).

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The heat sink depicted in the photos above holds a FET and a diode. In front of these is the intermediate buck inductor.

The main switchers, four Infineon IPA60R099 FETs, are installed in a full-bridge topology, and an LLC resonant converter boosts efficiency, providing an almost lossless switching operation.

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This is the main control board of the AX1500i, which is responsible for most of its circuits. On it we found a number of LM2902K quadruple operational amplifiers along with an MC56F8236 Freescale DSC (digital signal controller). In this section, the AX1200i, which has an identical control board, uses a 56F8014 DSC instead. On the same board there are also two fully integrated, mixed-signal system-on-a-chip MCUs from Silicon Lab, which play the role of a DSP; however, they are clocked at higher speeds. Their model numbers are C8051F310 and C8051F380. Both of them use the same 8051µC core, however, the core in the C8051F380 is clocked higher. Last, there is a USB 2.0 controller in the C8051F380 MCU, which allows communication between the PSU and the system.

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The board that holds the 5VSB regulation circuit, which is analog-controlled, sits on the front of the control board described above.

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Both DC-DC converters that generate the minor rails are housed on a separate daughterboard and are digitally controlled; hence they have almost perfect load regulation. On the same board the DC-DC converter for the -12V rail is also installed. Finally, we spotted an NCP1034DG buck PWM controller at the back of this daughterboard.

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Behind the two parallel main transformers is the PCB that holds all sixteen FETs that regulate the +12V rail. Several CapXon polymer capacitors handle the filtering of this rail. We expected to see Japanese caps here, but since these are polymer caps, we believe that the CapXon caps are adequate. On top of the caps there is a huge metal bar, which transfers power from the +12V regulation board to the modular PCB, through several pretty thick wires. Corsair used ferrite rings on these wires to suppress EMI/RFI noise.

On the front of the modular PCB several busbars transfer power to the sockets in order to minimize power loss as much as possible. On this side, we also found many Chemi-Con electrolytic caps for some extra ripple filtering, along with several small polymer caps by CapXon.

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Soldering quality on the main PCB is good; however, we have seen better examples from Flextronics in the past.

The AX1500i uses the same fan that is used in almost all of Corsair’s high-end PSUs. This fan utilizes a fluid dynamic bearing (FDB), which is considered among the best (if not the best), offering increased reliability and low noise output. The fan's model number is NR140P (12V, 0.22A).