LEPA G850-MAS Power Supply Review

Secondary Analysis

The LEPA G850-MAS uses a synchronous design, meaning that the rectifiers were replaced with MOSFETs. Also, this power supply uses a DC-DC design, meaning that it is basically a +12 V power supply, with the +5 V and +3.3 V outputs being generated through two smaller switching power supplies connected to the +12 V rail. Both designs are used to increase efficiency.

The +12 V output uses five IPD031N06L3 G MOSFETs, each supporting up to 100 A at 100° C in continuous mode or up to 400 A at 25° C in pulse mode, with a maximum RDS(on) of 3.1 mΩ. These transistors are controlled by an SP6019 integrated circuit, and they are located on a small daughterboard.

Figure 16: The +12 V transistors

The DC-DC converters are located on the same printed circuit board as the modular cabling system. Both are managed by an APW7159 PWM controller, with each output using a pair of AP72T03GH MOSFETs, each supporting up to 63 A at 25° C or 44 A at 100° C in continuous mode or up to 190 A at 25° C in pulse mode, with a maximum RDS(on) of 9 mΩ.

Figure 17: The DC-DC converters

Figure 18: The DC-DC converters

The outputs of this power supply are monitored by a WT7502 integrated circuit, which only supports over voltage (OVP) and under voltage (UVP) protections.

Figure 19: Monitoring circuit

This power supply uses a mix of Japanese electrolytic capacitors, from Chemi-Con, and solid capacitors to filter its outputs. See Figure 20.

Figure 20: Capacitors