The STMicroelectronics L6983I is a device specifically designed for isolated buck topology. The primary output voltage can be accurately adjusted, whereas the isolated secondary output is derived by using a given transformer ratio. No optocoupler is required. The primary sink capability up to -4.5 A (even during soft-start) allows a proper energy transfer to the secondary side as well as enabling a tracked soft-start of the secondary output. The control loop is based on a peak current mode architecture and the device operates in forced PWM. The 390 ns blanking time filters oscillations, generated by the transformer leakage inductance, making the solution more robust.