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Secondary Analysis

The Enermax NAXN 82+ 750 W has eight Schottky rectifiers attached to the secondary heatsink.

The maximum theoretical current each line can deliver is given by the formula I / (1 – D) where D is the duty cycle used and I is the maximum current supported by the rectifying diode. As an exercise, we can assume a duty cycle of 30%.

The +12 V output uses four KCQ60A06 Schottky rectifiers (60 A, 30 A per internal diode at 69° C, 0.67 V maximum voltage drop), giving us a maximum theoretical current of 171 A or 2,057 W for this output.

The +5 V output uses two PFR30L45CT Schottky rectifiers (30 A, 15 A per internal diode at 110° C, 0.52 V maximum voltage drop), giving us a maximum theoretical current of 43 A or 214 W for this output.

The +3.3 V output uses another two PFR30L45CT Schottky rectifiers (30 A, 15 A per internal diode at 110° C, 0.52 V maximum voltage drop), giving us a maximum theoretical current of 43 A or 141 W for this output.

Enermax NAXN 82+ 750 W power supplyFigure 14: The +3.3 V, +5 V, and +12 V rectifiers

This power supply uses a PS223 monitoring integrated circuit, which supports over voltage (OVP), under voltage (UVP), over current (OCP), and over temperature (OTP) protections. This chip has four OCP channels, one for +3.3 V, one for +5 V, and two for +12 V, correctly matching the number of +12 V rails advertised by the power supply manufacturer (two).

Enermax NAXN 82+ 750 W power supplyFigure 15: Monitoring circuit

The electrolytic capacitors available in the secondary are from Teapo, and are labeled at 105° C.

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Gabriel Torres is a Brazilian best-selling ICT expert, with 24 books published. He started his online career in 1996, when he launched Clube do Hardware, which is one of the oldest and largest websites about technology in Brazil. He created Hardware Secrets in 1999 to expand his knowledge outside his home country.