SilverStone Nightjar 500 W Power Supply Review

Secondary Analysis

The SilverStone Nightjar 500 W uses a synchronous design, meaning the Schottky rectifiers were replaced with MOSFETs. Also, the reviewed product uses a DC-DC design in its secondary. This means that the power supply is basically a +12 V unit, with the +5 V and +3.3 V outputs produced by two smaller power supplies connected to the main +12 V rail. Both designs are used to increase efficiency.

The +12 V output uses seven IRFB3307 MOSFETs, each one supporting up to 130 A at 25° C or 91 A at 100° C in continuous mode, or 510 A at 25° C in pulse mode, with a 5 mΩ RDS(on).

Here again, the manufacturer added a copper plate between the transistors and the heatsink in order to increase thermal dissipation. See Figure 16.

Figure 16: +12 V transistors

As explained, the +5 V and +3.3 V outputs are generated by two smaller DC-DC converters connected to the main +12 V output. Each converter is located on a small daughterboard. Each converter is controlled by an APW7164 integrated circuit and uses three MOSFETs. One of them is an NTD4969N (up to 41 A at 25° C, 29 A at 100° C in continuous mode, 150 A at 25° C in pulse mode, 9 mΩ), but the other two we couldn’t identify, as their markings were removed. Notice how these converters use tantalum (SMD) capacitors.

Figure 17: One of the DC-DC converters

Figure 18: One of the DC-DC converters

This power supply uses a WT7505 monitoring integrated circuit, which supports over voltage (OVP), under voltage (UVP), and over current (OCP) protections.

Figure 19: Monitoring circuit

This power supply uses only high-end electrolytic capacitors, since temperature is the main concern when designing fanless power supplies. The secondary uses a combination of Japanese electrolytic capacitors (from Chemi-Con), solid electrolytic capacitors, and tantalum capacitors on the solder side of the printed circuit board.