Patent ID: 6842350

Claim:
A dc-to-dc converter capable of translating a first dc voltage into a second dc voltage for application to a load of variable power requirement, the dc-to-dc converter comprising: (a) a pair of dc terminals for providing a first dc voltage; (b) a controllable switching device connected between the pair of dc terminals and driven to have alternating conducting and nonconducting periods for repeatedly interrupting the first dc voltage; (c) inductance means connected in series with the switching device; (d) a rectifying and smoothing circuit connected to the inductance means for providing a second dc voltage to be applied to a load; (e) a flyback period detector circuit for providing an output signal indicative of a period of time during-which the inductance means is developing a flyback voltage; (f) a feedback circuit for creating a feedback signal for holding the second dc voltage constant; (g) a conduction termination circuit connected to the feedback circuit for determination of moments at which the conducting periods of the switching device are to be terminated; (h) a switch control and mode select circuit connected to the flyback period detector circuit, the conduction termination circuit, and the switching device, for driving the switching device in two different modes, the switch control and mode select circuit having a pulse generator circuit for providing clock pulses, and means for forming a first switch control signal for driving the switching device in first mode when the flyback voltage terminates earlier than each clock pulse, and forming a second switch control signal for driving the switching device in second mode, in which each on-off cycle of the switching device is longer than in the first mode, when the flyback voltage terminates later than each clock pulse.