SHARE

## Secondary Analysis

The Enermax NAXN 82+ 550 W uses a regular design in its secondary, with Schottky rectifiers.

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 percent.

The +12 V output uses three SBR40U60CT Schottky rectifiers (40 A, 20 A per internal diode at 100° C, 0.60 V maximum voltage drop), which gives us a maximum theoretical current of 86 A or 1,029 W for this output. The NAXN 80+ 600 W uses three 30 A rectifiers here, but the maximum theoretical current and power are the same.

The +5 V output uses one SBR30U30CT Schottky rectifier (30 A, 15 A per internal diode at 140° C, 0.54 V maximum voltage drop), which gives us a maximum theoretical current of 21 A or 107 W for this output. The NAXN 80+ 600 W uses two of these rectifiers instead of only one, thus having double the maximum theoretical current and power.

The +3.3 V output uses one STPS40L45CW Schottky rectifier (40 A, 20 A per internal diode at 130° C, 0.70 V maximum voltage drop), which gives us a maximum theoretical current of 29 A or 94 W for this output. This component is a lower voltage drop version of the one used in the NAXN 80+ 600 W.

Figure 14: The +5 V rectifier and two of the +12 V rectifiers

Figure 15: One of the +12 V rectifiers and the +3.3 V rectifier

This power supply uses an ST9S429 monitoring integrated circuit, which apparently is a rebranded S3515. This chip supports over voltage (OVP), under voltage (UDP), and over current (OCP) protections. There are two +12 V OCP channels, matching the number of +12 V rails advertised by the manufacturer.

Figure 16: Monitoring circuit

The electrolytic capacitors that filter the outputs are also from Samxon and are labeled at 105° C, as usual.

## Contents

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.