Synchronous rectification has been found to be very effective in reducing conduction losses of buck and boost converters and secondary side rectifiers. However, implementation of the synchronous rectification is far from being simple. The control signals need to be precise, and in the noisy environment of a switch mode power supply, false triggering is hard to avoid. This is particularly true when the operation is in the DCM mode when resonant induced oscillations prevail.
In recent years, a new breed of control IC have been popping up: “ideal rectifier” controllers. These are in fact very similar to the synchronous rectifiers (replacing the conducting diode by a MOSFET) but unlike previous solutions, they are autonomous. That is, they do not require a control signal as the classical synchronous rectifiers do. A key issue in this case is of course the question of response time and in particular the delay from ‘on’ to ‘off’ state. It would be nice to see data on the response of these devices in a form similar to the plots of diode reverse recovery. I have not seen such data.
It would extremely interesting to read testimonial of actual use of such “ideal rectifiers” in practical circuits.
For a primer on the “Ideal rectifier” see
