Abstract: A digital SMPC (1) comprises an SMPS Transformer primary side (2) and an SMPS secondary side (3). Opto-couplers (4) perform bi-directional communication between primary side and secondary side communication circuits (5, 6). The primary side communication circuits (5) are connected via a loop controller (7) to the primary side (2). The secondary side communication circuits 6 are connected to the secondary side 3 via an ADC (8). The analogue-to-digital converter (ADC, 8) digitises the output voltage V0 on the secondary side. The secondary side communication module (6) encodes this value and uses the data couplers (4) to transmit it over the isolation barrier. The primary side communication module (5) receives and decodes the value and provides it to the loop controller module (7). The loop controller (7) is implemented as a Digital Signal Processor (DSP) or a hardware PID-controller.