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 Kingwin.
The design used by this power supply is ridiculous, as it uses the same design as old AT and ATX power supplies: instead of using power MOSFET transistors on the switching section, it uses regular BJT transistors. The design used on the secondary is also old, as we will talk about on next page.
The main problem with this design is efficiency. FET transistors have high impedance, and the higher the impedance, the less power the component will draw from the circuit for its own operation – meaning less consumption and energy waste. Since this power supply uses regular transistors on its switching section, it is very unlikely that it can have high efficiency.
This same design is used on two other low-end power supplies without PFC we’ve reviewed recently, Seventeam ST-420BKV and Huntkey Green Star 450 W.
This power supply uses one RS605 rectifying bridge on its primary stage, which can deliver up to 6 A (rated at 75º C).
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Figure 7: Rectifying bridge.
On the switching section two 2SC2625 NPN power transistors are used. They can deliver up to 10 A continuous mode or up to 20 A in pulse mode, which is the case. Both values are given at 25º C.
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Figure 8: Switching transistors.
On Figure 9 you can find the schematics of a very old AT power supply. Kingwin ABT-450MM uses this same basic schematics on both primary and secondary sections. This is simply ridiculous for a power supply being sold in 2008.
Figure 9: Schematics of a very old AT power supply. This power supply uses this same design.
