Half Bridge resonant SMPS capable of delivering 350W continuous and 500W peak power. the stock available output voltages are +-27V DC at 6.5A, +-31.5V DC at 5.5A, and +-54V DC at 3.3A continuous. other voltages are available on request. it uses open loop half bridge resonant topology and the output voltage is within +5 and -10% of the nominal voltage when the current draw is varying from 0-100%. The main advantage is lower size and cost compared with a similar regulated SMPS and better efficiency compared with the regulated SMPS's due to the fact that the transformer is driven with almost 50% duty cycle all the time, and the current through the switches has sinusoidal shape, and there are no output inductors. The SMPS features overcurrent protection which limit the output current at about 140% of the maximum peak power, about 700W. For best performances, there are two power supply versions, one for 110V mains supply voltage and one for 230V mains voltage, knowing the fact that some universal mains power supplies rely on voltage doubling when is used with 110V input, this lowering the global efficiency and maximum power capability. This power supply is suitable for both class AB and class D/T amplifiers, which have the PSRR greater or at least 54dB. Target applications for this power supply unit include the TA3020 based amplifiers and IRS2092 amplifiers for the +-54V version and TDA892x or TA2022 amplifiers for the +-27V or +-31.5V version.