3R System AK 500 Power Supply Review

Secondary Analysis

The 3R System AK 500 uses a regular design in its secondary, with Schottky rectifiers.

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. As an exercise, we can assume a duty cycle of 30 percent.

The +12 V output uses two PFR60L60CT Schottky rectifiers (60 A, 30 A per internal diode at 100° C, 0.65 V maximum voltage drop). This gives us a maximum theoretical current of 86 A or 1,029 W for the +12 V output.

The +5 V output uses two FCH30A10 Schottky rectifiers (30 A, 15 A per internal diode at 105° C, 0.88 V maximum voltage drop). This gives us a maximum theoretical current of 43 A or 214 W for the +5 V output.

The +3.3 V output uses two PFR30L45CT Schottky rectifiers (30 A, 15 A per internal diode at 100° C, 0.52 V maximum voltage drop). This gives us a maximum theoretical current of 43 A or 141 W for the +3.3 V output.

Figure 14: The +3.3 V, +12 V, and +5 V rectifiers

This power supply uses a GR8323 monitoring integrated circuit, which supports over voltage (OVP), under voltage (UVP), over current (OCP), and over temperature (OTP) protections. This chip offers two +12 V OCP channels.

Figure 15: Monitoring circuit

The electrolytic capacitors that filter the outputs are from Kingcon and labeled at 105° C, as usual.