Switch mode converter and improved deadband control therefor

DETAILED DESCRIPTION It is an object of the present invention to prevent cross-conduction in a switch mode converter of its primary switches under essentially all operating conditions of the converter.
It is another object of the present invention to prevent cross-conduction in a switch mode converter of its primary switches under essentially all operating conditions of the converter essentially without shortening the maximum converter duty cycle available.
It is another object of the present invention to switch on one primary switch of a pair of primary switches coupled to an input voltage in a switch mode converter only when both primary switches of the pair are in fact off.
It is another object of the present invention to provide a switch mode converter in which any of the foregoing objects are realized.
The invention disclosed herein achieves the above and other objects, and, briefly, provides a converter which monitors the actual state of a primary switch means having a plurality of primary switches which are selectively turned on in response to control signals applied to the primary switch means, and permits a primary switch of a pair of primary switches coupled to an input voltage to be turned on only when both primary switches of the pair are off.
The primary switch means comprises at least first and second primary switches, at least first and second voltage inputs, control input means and an output, and couples the first and second voltage inputs to the output selectively through one of the primary switches in response to control signals applied to the control input means.
The converter generates turn-on control signals to turn one primary switch on during a first time period (e.
g.
, approximately one half of the switching cycle for a two switch primary switch means) and turn-on control signals to turn the other primary switch on during a second time period (e.
g.
, approximately the other half cycle of a two switch primary switch means) and does not generate turn-on signals during third time periods (e