Secondary Analysis

This power supply uses a synchonous design in its secondary, meaning that the diodes were replaced with transistors in order to increase efficiency.

The +12 V output is rectified using two IRLB3036 MOSFETs, each one capable of handling up to 270 A at 25° C or up to 190 A at 100° C in continuous mode, or up to 1,100 A at 25° C in pulse mode. This translates into a maximum theoretical current of 271 A at 100° C or 3,257 W!

FSP Aurum Gold 700 power supplyFigure 13: +12 V transistors

The +5 V and +3.3 V outputs share the same circuitry and are rectified by two IPD031N03L MOSFETs – 90 A at 100° C in continuous mode and 400 A at 25° C in pulse mode, 3.1 mΩ RDS(on) – and two IPD050N03L MOSFETs. The four transistors are located on the solder side of the printed circuit board.

FSP Aurum Gold 700 power supplyFigure 14: The +5 V and +3.3 V transistors

The secondary transistors are controlled by an FSP6601, another proprietary chip from FSP.

FSP Aurum Gold 700 power supplyFigure 15: Synchronous controller

The secondary is monitored by a WT7579 integrated circuit, which is manufactured exclusively for FSP. This chip supports over voltage (OVP), under voltage (UVP), overcurrent (OCP), and over temperature (OTP) protections. There are four +12 V over current protection (OCP) channels, matching the number of +12 V rails advertised by the manufacturer.

FSP Aurum Gold 700 power supplyFigure 16: Monitoring circuit

All electrolytic capacitors used in the secondary are from CapXon and labeled at 105° C.

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.