Patent ID: 7538534

Claim:
A power converter circuit comprising: input terminals for receiving input power; output terminals for delivering constant current to a load; a cascaded power converter coupled to the input and output terminals comprising: an input stage, the input stage having an input boost inductor; an output stage, the output stage being of a buck type comprising an output filter inductor for smoothing current in the load; at least one coupling capacitor coupled to coupled to the input boost inductor and to the output filter inductor; a first current sensor coupled to the input stage for monitoring current in the input stage; a second current sensor coupled to the output stage for monitoring current in the output filter inductor; a first reference current; a second reference current; a first comparator circuit coupled to the first current sensor and the first reference current; a second comparator circuit coupled to the second current sensor and the second reference current; and a pulse width modulator circuit; a controlled switching circuit for coupling an input of the input stage to the input terminals and for coupling an output of the input stage to an input of said output stage; wherein the first comparator changing an output state when output of the first current sensor exceeds the first reference; wherein the second comparator changing an output state when output of the second current sensor exceeds the second reference; wherein the pulse width modulator circuit controls the controlled switching circuit based on output states of the first and second comparators.