We were very curious to check what components were chosen for the power section of this power supply and also how they were set together, i.e. the design used. We were willing to see if the components could really deliver the power announced by PC Power & Cooling.
From all the specs provided on the databook of each component, we are more interested on the maximum continuous current parameter, given in ampères or amps for short. To find the maximum theoretical power capacity of the component in watts we need just to use the formula P = V x I, where P is power in watts, V is the voltage in volts and I is the current in ampères.
We also need to know under which temperature the component manufacturer measured the component maximum current (this piece of information is also found on the component databook). The higher the temperature, the lower current semiconductors can deliver. Currents given at temperatures lower than 50º C are no good, as temperatures below that don’t reflect the power supply real working conditions.
Keep in mind that this doesn’t mean that the power supply will deliver the maximum current rated for each component as the maximum power the power supply can deliver depends on other components used – like the transformer, coils, capacitors, the PCB layout, the wire gauge and even the width of the printed circuit board traces – not only on the specs of the main components we are going to analyze.
For a better understanding of what we are talking here, please read our Anatomy of Switching Power Supplies tutorial.
This power supply uses one GBJ1506 rectifying bridge on its primary stage, which can deliver up to 15 A (rated at 100º C).
The active PFC circuit from this power supply uses two power MOSFET transistors (20N60C3 – the same one used by several other power supplies we took a look). Other power supplies from around the same power range of Silencer 610 EPS12V like OCZ StealthXStream 600 W and Zalman ZM600-HP use three transistors here instead of two. Each 20N60C3 can handle up 300 A @ 25º C each in pulse mode (which is the case).
On the switching section two FQPF18N50V2 power MOSFET transistors in two-transistor forward configuration are used, and each one has a maximum rated current of 72 A in pulsating mode, which is the mode used, as the PWM circuit feeds these transistors with a square waveform. Interesting to note that these are the same transistors used by several other power supplies, like OCZ StealthXStream 600 W, Zalman ZM600-HP, OCZ GameXstream 700 W and Corsair HX620W.
The active PFC transistors, the switching transistors and the PFC diode are installed on the same heatsink, as you can see on Figure 10.
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Figure 10: Primary semiconductors.
This power supply uses four Schottky rectifiers on its secondary.
The +12 V output uses two 30A50CT in parallel, each one capable of handling up to 30 A at 25º C, so the +12 V output has a maximum theoretical current of 60 A or 720 W.
The +5 V output uses one 30L30CT, which is capable of handling up to 30 A at 140º C, so the +5 V output has a maximum theoretical power of 150 W.
The +3.3 V output uses one 30A40CT, capable of handling up to 30 A at 135º C, so the +3.3 V output has a maximum theoretical power of 99 W.
Even though this power supply has a separated rectifier for the +3.3 V output, this rectifier is connected to the same transformer output as the +5 V line, so the maximum current +5 V and +3.3 V can pull together is limited by the transformer.
As we said earlier, the maximum power the power supply can deliver depends on other components used – like the transformer, coils, capacitors, the PCB layout, the wire gauge and even the width of the printed circuit board traces. The numbers presented are just a theoretical exercise.
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Figure 11: The four Schottky rectifiers used on the secondary.
This power supply uses a mix of Japanese (Chemi-Con) and Taiwanese (OST) electrolytic capacitors. The big electrolytic capacitor from the active PFC circuit is rated at 85º C while all other smaller capacitors are rated 105º C.
