Half Bridge resonant SMPS capable of delivering 500W continuous and 700W peak power. 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 160% of the maximum power, about 800W. 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 multiple TDA892x or TA2022 amplifiers for the +-27V or +-31.5V version. The size of the board is 100x100mm and the maximum height from the PCB is 36mm, allowing to be installed in 1RU cases with proper clearance under the PCB.