A constant frequency series-parallel resonant converter with dual-edge PWM to implement secondary-side control

48V Voltage regulators (VR) can be used to improve the system efficiency of telecom and data centres by eliminating a converter stage in intermediate bus architectures. By adopting resonant converters to implement the 48V VRs, small size, and improved transient performance can be achieved through high switching frequency. This work proposes the use of dual-edge PWM secondary-side control of a series-parallel resonant converter operating at a constant 4MHz to provide 30W at 1.2V from a 48V input. This control method eliminates the opto-coupler from the control loop in applications with isolation requirements; and achieves fast dynamic performance through standard linear control, without the use of a current sensor.