Patent ID: 8232787

Claim:
An apparatus for monitoring the pulse time of one or more switches within a DC to DC power supply comprising: a timing circuit responsive to a switching confirmation signal which indicates that a switch has reached a desired switching state, said timing circuit arranged to commence timing and to monitor for control signals being sent to the one or more switches and to indicate whether an elapsed period between the switching confirmation signal and the control signal is too long or too short, said timing circuit arranged to generate a too short mask extending from a first time after receipt of the switching confirmation signal to a second time after receipt of the switching confirmation signal, said timing circuit further arranged such that the occurrence of the control signal between the first and second times give rise to an indication that the pulse time of an associated switch pulse time is too short, and said timing circuit arranged to generate a too long mask extending from a third time measured from receipt of the switching confirmation signal, said timing circuit further arranged such that the failure of the control signal to occur before the third time gives rise to an indication that the associated switch pulse time is too long.