Antec TruePower Quattro 850 W Power Supply Review

Secondary Analysis

This power supply uses a synchronous topology on the secondary. This is the second power supply we’ve seen using such design (the other one was OCZ ProXStream 1000 W). On this topology the diodes are replaced with MOSFET transistors. In theory this configuration provides a higher efficiency, as MOSFET transistors have a lower voltage drop compared to Schottky rectifiers (0.1 V or less vs. 0.5 V). This leads to less power wasted and thus higher efficiency.

For rectifying the +12 V output four IRL2203N power MOSFET transistors are used, each one capable of handling up to 82 A at 100° C in continuous mode, or up to 400 A in pulse mode (at 25° C). The maximum theoretical current the +12 V 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 (which in this case was replaced by two 82 A transistors in parallel). Just as an exercise, we can assume a typical duty cycle of 30%. This would give us a maximum theoretical current of 234 A or 2,811 W for the +12 V output – which is clearly overspec’ed. The maximum current this line can really deliver will depend on other components, in particular the coil used.

For rectifying the +5 V output two IRL3705Z power MOSFET transistors are used, each one capable of handling up to 61 A at 100° C in continuous mode, or up to 340 A in pulse mode (at 25° C). This would give us as maximum theoretical current of 87 A or 436 W for the +5 V output.

And for rectifying the +3.3 V output other two IRL3705Z power MOSFET transistors are used, giving a maximum theoretical current of 87 A or 287 W for this line.

Of course this is just an exercise and the maximum current the power supply can really deliver depends on the other components. But we could see that the rectification circuit is clearly overspec’ed.

The +5VSB output uses a regular Schottky diode pack, SR1060, capable of delivering up to 10 A at 25° C.

Figure 14: Two +12 V transistors, +5 V transistor, +3.3 V transistor and +5VSB rectifier. The other transistors are on the other side of the heatsink.

This power supply uses a PS223 monitoring integrated circuit, which is in charge of the power supply protections, like OCP (over current protection). OCP was really activated, as we will talk about later. This IC also provides over voltage protection (OVP), under voltage protection (UVP) and over temperature protection (OTP), but not over power protection (OPP).

Figure 15: PS223 monitoring integrated circuit.

This power supply has two thermal sensors: one for controlling the speed of the fan and one for shutting down the power supply in case of an overheating situation (i.e., OTP, over temperature protection). It is interesting to note that Antec doesn’t list OTP as a feature for this power supply, but the monitoring IC supports this feature and it is connected to a thermal sensor.

Figure 16: Thermal sensors.

The active PFC electrolytic capacitor is Japanese from Chemi-Con (rated at 105° C) but the secondary capacitors are Taiwanese, from Teapo (rated at 105° C).