Buck boost switching regulator with duty cycle limiting
First Claim
1. A duty-cycle limited, buck-boost, switching regulator including first and second switches for connecting, with adjustable duty cycle, opposite terminals of an inductance to different ones of terminals for receiving operating voltage and said regulator comprisingfirst and second means, responsive to a regulator output signal, for developing first and second duty cycle control signals for adjusting duty cycles of said first and second switches, andmeans for limiting a voltage difference between said control signals to a maximum value substantially less than a value corresponding to a maximum range of duty cycle adjustment of one of said switches.
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Accused Products
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.
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Citations
9 Claims
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1. A duty-cycle limited, buck-boost, switching regulator including first and second switches for connecting, with adjustable duty cycle, opposite terminals of an inductance to different ones of terminals for receiving operating voltage and said regulator comprising
first and second means, responsive to a regulator output signal, for developing first and second duty cycle control signals for adjusting duty cycles of said first and second switches, and means for limiting a voltage difference between said control signals to a maximum value substantially less than a value corresponding to a maximum range of duty cycle adjustment of one of said switches.
Specification