Abstract: In a buck-boost, switching regulator, separate signals are developed to control duty cycles of regulator switches. Control exercised by a pair of feedback-determined reference signal voltages through which a ramp signal is swept at inputs of separate comparators, comparator outputs control respective switches. A predetermined maximum voltage difference is permitted between the reference signal voltages. The reference used to control switching of one end of the regulator inductance is limited to a minimum voltage corresponding to a minimum duty cycle greater than 0% while the other reference is used to control the other end of that inductance and is limited to a maximum voltage corresponding to a minimum duty cycle less than 100%. A current limiting feedback from one of the switches is operated in response to current in excess of a predetermined level to force the ramp signal to a level corresponding to 0% duty cycle for both switches at the same time.

Abstract: First and second transistor current sources of complementary conductivity types are connected in series with an output connection between them in the series connection. Input signals control the conduction level of one of the sources so that it diverts correspondingly variable amounts of current of the other source away from the output connection in accordance with a first linear characteristic. Additional transistor current source circuits are provided, and responsive to a predetermined level of the same input signals, for diverting substantially different amounts of current away from the output connection in accordance with a second linear characteristic of different slope from the first characteristic.