Secondary Analysis

This power supply has four Schottky rectifiers on its secondary using the same configuration used by high-end power supplies.

The +5 V output is produced by a MBRP3045N Schottky rectifier, which supports up to 30 A at 100º C each. So the maximum theoretical power the +5 V output can deliver is of 150 W. Of course the maximum current (and thus power) this line can really deliver will depend on other components, especially the transformer, the coil, the capacitor and the wire gauge used.

The +3.3 V output is produced by another MBRP3045N Schottky rectifier, which supports up to 30 A at 100º C. So the maximum theoretical power the +3.3 V output can deliver is of 99 W. As mentioned the real power this line can deliver depends on other factors.

The +12 V output is produced by two MBR2060CT Schottky rectifiers connected in parallel. Since each one supports up to 20 A at 125º C we have a maximum theoretical current for the +12 V output of 40 A or 480 W. Of course the maximum current (and thus power) this line can really deliver will depend on other components, especially the transformer, the coil, the capacitor and the wire gauge used, as we mentioned before.

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Figure 15: +3.3 V, +5 V and +12 V rectifiers.

This power supply uses separated filtering stages for each 12 V virtual rail, which is great.

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).

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Figure 16: PS223 monitoring integrated circuit.

The thermal sensor is located under the secondary heatsink, as you can see on Figure 17 (we took this picture with the heatsink removed). This sensor is used to control the fan speed according to the power supply internal temperature and to shut down the power supply in an overheating situation. As we mentioned, the monitoring IC supports this protection and Zalman says this unit features this protection. We, however, couldn’t test this feature, as the power supply was always working very cool.

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Figure 17: Thermal sensor.

On this power supply all electrolytic capacitors are Taiwanese from CapXon, with the active PFC capacitor rated at 85º C and the secondary capacitors rated at 105º C.

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