3R System iCEAGE IA450HP80 450 W Power Supply Review

Primary Analysis

On this page we will take an in-depth look at the primary stage of 3R System iCEAGE IA450HP80. For a better understanding, please read our Anatomy of Switching Power Supplies tutorial.

This power supply uses one KBU806 rectifying bridge, which supports up to 8 A at 65° C if a heatsink is used, which is not the case. At 115 V this unit would be able to pull up to 920 W from the power grid; assuming 80% efficiency, the bridge would allow this unit to deliver up to 736 W without burning itself out. Of course we are only talking about this component and the real limit will depend on all other components from the power supply.

Figure 9: Rectifying bridge.

Usually low-cost power supplies without PFC circuit are based on the obsolete half-bridge design, so it came as a surprise for us to see that iCEAGE IA450HP80 is based on a two-transistor forward design, which is the same design used by power supplies with active PFC. This is the first time we’ve seen a power supply without PFC using this topology.

In the switching section, two 2SK4108 power MOSFET transistors are used on the two-transistor forward configuration, as mentioned. Each transistor is capable of handling up to 20 A at 25° C i
n continuous mode, or up to 80 A at 25° C in pulse mode. Unfortunately the manufacturer does not provide the current limits at 100° C. These transistors present an RDS(on) of 210 mΩ. This number measures the resistance provided by the transistors when they are turned on; the lower this number, the better (higher efficiency).

Figure 10: Switching transistors.

The switching transistors are controlled by a UC3843 PWM controller.

Figure 11: PWM controller.

Now let’s take a look at the secondary of this power supply.