Gigabyte Odin Plus 700 W Power Supply Review
Secondary Analysis
Contents
This power supply has ten Schottky rectifiers on its secondary heatsink, using a DC-DC project. This means that this power supply is basically a +12 V unit and the +5 V and +3.3 V outputs are generated by two smaller switching-mode power supplies that converts the +12 V into the required voltage.
The +12 V output is produced by eight of the available rectifiers. The other two rectifiers are used by the +5VSB output and by the -12 V output. All +12 V Schottky rectifiers are STPS20H100CT models, each one being able to deliver up to 20 A (10 A per internal diode at 160° C, 0.88 V maximum voltage drop).
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. Just as an exercise, we can assume a typical duty cycle of 30%.
As explained, the +12 V line is also used to generate the +5 V and +3.3 V outputs. Just as an exercise, if we pull all the current/power only on the +12 V output, the maximum theoretical power of this unit would be 114 A or 1,371 W. The real amount of current/power each output can deliver is limited by other components.
Figure 12: +5 VSB, +12 V and -12 V rectifiers.
The +5 V and +3.3 V outputs are generated by two small switching-mode power supplies attached to the +12 V output. Each one of these power supplies is available on a small daughterboard. Each board is controlled by an APW7073 PWM controller, with the +5 V board using one FDD8880 and two FDD8896 MOSFETs and the +3.3 V board using one NTD4809NH and two NTD4806N MOSFETs.
Figure 13: +5 V and +3.3 V power supplies.
The secondary of Odin Plus 700 W uses only solid capacitors, as you can see in Figure 14.
Figure 14: Solid caps.
The outputs are monitored by a WT7527 integrated circuit, which supports OVP (over voltage protection), UVP (under voltage protection) and four OCP (over current protection) channels, one for +3.3 V, one for +5 V, and two for +12 V. An LM339 voltage comparator is used to expand the number of over current protection channels.
Figure 15: Monitoring integrated circuit.
Figure 16: Voltage comparator.