Secondary Analysis
Contents
This power supply has six Schottky rectifiers on its secondary, two for each positive voltage output (+12 V, +5 V and +3.3 V). Zalman ZM360B-APS uses only four rectifiers and we can’t tell about Zalman ZM460B-APS yet, even though we suspect Zalman ZM460B-APS and SilverStone Strider ST50F are identical.
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%.
The +12 V output is produced by two MBR2560CT Schottky rectifiers connected in parallel. Since each one supports up to 30 A at 130° C (15 A per internal diode) we have a maximum theoretical current for the +12 V output of 43 A or 514 W [(15 A x 2) / (1 – 0.30)]. Of course the maximum current (and thus power) this line can really deliver will depend on other components, especially the coil.
The +5 V output is produced by two MBR3045N Schottky rectifiers, supporting up to 30 A at 100° C each (15 A per internal diode). So the maximum theoretical current the +5 V output can deliver is of 43 A or 214 W. Of course the maximum current (and thus power) this line can really deliver will depend on other components, especially the coil, as we mentioned before.
The +3.3 V output is produced by other two MBRP3045N Schottky rectifiers, supporting up to 30 A at 100° C each (15 A per internal diode). So the maximum theoretical current the +3.3 V output can deliver is of 43 A or 141 W. As mentioned the real power this line can deliver depends on other factors.
Figure 15: +12 V, +5 V and +3.3 V rectifiers.
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 16: PS223 monitoring integrated circuit.
The thermal sensor is located under the secondary heatsink, as you can see in 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 SilverStone says this unit features this protection. We, however, couldn’t test this feature, as the power supply was always working very cool.
Figure 17: Thermal sensor.
On this power supply all electrolytic capacitors are Taiwanese, from CapXon, with the active PFC capacitor rated at 85° C and the secondary capacitors rated at 105° C.
