SilverStone Nightjar 400 W Power Supply Review

Secondary Analysis

This power supply uses a DC-DC design on its secondary, meaning that it is basically a +12 V power supply with the +5 V and +3.3 V outputs being produced from the main +12 V output by two smaller power supplies. This design is used by several other power supplies and is proving to be a winner for building high-efficiency models.

The main +12 V output is produced by four STPS6045CW Schottky rectifiers , each one capable of handling up to 60 A (30 A per internal diode at 150° C, maximum voltage drop of 0.63 V). This means that the main +12 V output can, in theory, handle up to 171 A. Of course it is used by all outputs, but if all this theoretical current was delivered only to the +12 V output, this would give us 2,057 W. Is this power supply overspec’ed or what?

Figure 14: +12 V rectifiers.

The +5 V and +3.3 V outputs are generated by four NTB125N2R Power MOSFET transistors (two for each output), each one capable of handling up to 125 A at 25° C with an RDS(on) of only 3.7 mΩ, which is very low (excellent). Once again, these outputs are amazingly overspec’ed. Each pair of transistors is controlled by an L6730 controller.

Figure 15: +5VSB rectifier and transistors from the +5 V and +3.3 V power supplies.

Figure 16: DC-DC controllers.

The secondary is monitored by a PS223 monitoring integrated circuit, which is in charge of the power supply protections, like OCP (over current protection), OVP (over voltage protection), UVP (under voltage protection) and OTP (over temperature protection, not implemented on this power supply).

Figure 17: Monitoring integrated circuit.

Electrolytic capacitors from the secondary are from Teapo.