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Seasonic Focus Plus Platinum 750 PSU Review: Efficiency On A Budget

Teardown & Component Analysis

Before proceeding with this page we strongly encourage you to a look at our PSUs 101 article, which provides valuable information about power supplies and their operation, allowing you to better understand the components we're about to discuss.

General Data
Manufacturer (OEM)Seasonic
Platform ModelPX
Primary Side
Transient Filter4x Y caps, 2x X caps, 2x CM chokes, 1x MOV, 1x CM02X
Inrush ProtectionNTC thermistor & diode
Bridge Rectifier(s)2x GBU1506 (600V, 15A @ 100°C)
APFC MOSFETs2x Infineon IPP50R140CP (550V, 15A @ 100°C, 0.14Ω)
APFC Boost Diode1x STMicroelectronics STTH8S06D (600V, 8A @ 125°C)
Hold-up Cap(s)1x Nippon Chemi-Con (400V, 560uF, 2000h @ 105°C, CE)
Main Switchers4x Infineon IPP50R250CP (550V, 9A @ 100°C, 0.25Ω)
APFC ControllerChampion CM6500UNX
Resonant ControllerChampion CM6901T6X
TopologyPrimary side: Full-bridge & LLC resonant controller Secondary side: Synchronous rectification & DC-DC converters
Secondary Side
+12V MOSFETs4x Nexperia PSMN1R8-40YLC (40V, 100A @ 25°C, 1.8mΩ)
5V & 3.3VDC-DC Converters: 6x Infineon BSC0906NS (30V, 40A @ 100°C, 4.5mΩ) PWM Controller: APW7159
Filtering CapacitorsElectrolytics: Chemi-Con (1-5000 @ 105°C, KZE), Chemi-Con (4-10,000 @ 105°C, KY), Chemi-Con (105°C, W) Polymers: Chemi-Con
Supervisor ICWeltrend WT7527V (OVP, UVP, OCP, SCP, PG)
Fan ModelHong Hua HA1225M12F-Z (120mm, 12V, 0.45A, 2050 RPM, fluid dynamic bearing)
5VSB Circuit
Standby PWM ControllerExcelliance EM8569
RectifierP10V45SP SBR (45V, 10A @ 50% Duty Cycle)

This is the well-known Focus platform, which took over the mid-range category thanks to its high performance per dollar ratio. According to our sources, it's proving to be very reliable so far, although it's still fairly new. Nevertheless, given the high-quality components we find inside, we are sure it'll fare well over time.

The SSR-750PX utilizes a full bridge topology on its primary side, along with an LLC resonant converter. On the secondary side, four FETs installed on the PCB's solder side rectify the +12V rail. Meanwhile, the minor rails are generated through a couple of DC-DC converters. Both the electrolytic and polymer caps are provided by Chemi-Con. It is always nice to see polymer caps used in PSUs since they offer longer lifetimes and low ESR. But they don't have the capacity you get from electrolytics, which power supplies need (especially when it comes to transient response and hold-up time).

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Here are some photos showing the PSU’s major parts.

The following video shows the SSR-750PX’s internals.

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