Abstract: A system includes a control circuit having a voltage input and a control circuit output. The control circuit produces a control voltage at the control circuit output having a magnitude inversely related to a magnitude of an input voltage at the input voltage input. A VCO has a VCO control input and a VCO clock output. The VCO control input is coupled to the control circuit output. The VCO produces a VCO clock on the VCO clock output having a frequency that is a function of the control voltage. A protection circuit has a first clock input, a second clock input, and a protection circuit output. The second clock input is coupled to the VCO clock output. The protection circuit generates a protection circuit output signal at the protection circuit output based on a difference in frequency between a clock signal at the first clock input and the VCO clock.

Abstract: In some examples, an apparatus includes: a power stage having a power stage voltage input, a power stage control input, and a power stage output; a controller having a power stage control output coupled to the power stage control input, an output voltage status terminal, and a status signal input; a transformer having a primary side coil coupled to the power stage output, and a secondary side coil; a feedback voltage processor having a feedback input coupled to the secondary side coil, and a feedback output; a control message generator having a control input coupled to the secondary side coil, and a control message output; a status signal generator having first and second signal inputs coupled to respective feedback and control message outputs, and a status signal output; and a communication channel device coupled between the status signal input and output.