Closed-loop digital control system for a DC/DC converter

#The present invention relates to DC/DC converters, and more particularly to digital control systems for DC/DC converters.

#DC/DC converters are electronic devices that employ inversion and/or rectification to transform DC voltage at a first level into DC voltage at a second level. For example, a DC/DC converter may step-up DC voltage, step-down DC voltage, or may be capable of both stepping up and stepping down DC voltage. DC/DC converters typically include one or more inductors. Inductors are circuit elements that operate based on magnetic fields. The source of the magnetic field is charge that is in motion, or current. If current varies with time, the magnetic field that is induced also varies with time. A time-varying magnetic field induces a voltage in conductors that are linked by the magnetic field.

#Referring to FIG. 1A, a DC/DC converter 10 includes an inductor 12. Inductors 12 in DC/DC converters 10 typically communicate with at least one switch and at least one capacitor. For example, the switch may be a transistor and the capacitor may be an output capacitor that filters an output voltage of the DC/DC converter 10. A control module may communicate with the switch to control when the inductor 12 charges or discharges. For example, when the switch is on, the input current may flow through the switch and inductor 12 to the capacitor while building up the magnetic field of the inductor 12. When the switch is off, the inductor 12 opposes the drop in current and supplies current to the capacitor.

#The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein:

#FIG. 1A is a functional block diagram and electrical schematic of an inductor implemented in an exemplary DC/DC converter according to the prior art;

#FIG. 1B is a functional block diagram and electrical schematic of a coupled inductor circuit with two conductors implemented in an exemplary DC/DC converter according to the prior art;

#The following description of the preferred embodiment(s) is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses. For purposes of clarity, the same reference numbers will be used in the drawings to identify similar elements. As used herein, the term module refers to an application specific integrated circuit (ASIC), an electronic circuit, a processor (shared, dedicated, or group) and memory that execute one or more software or firmware programs, a combinational logic circuit, and/or other suitable components that provide the described functionality.

#Referring now to FIG. 2, an open-loop control system 28 for a DC/DC converter 30 includes a control module 32. The DC/DC converter 30 includes first, second, third, and fourth transistors 34, 36, 38, and 40, respectively. Sources (or second terminals) of the first and third transistors 34 and 38, respectively, communicate with drains (or first terminals) of the second and fourth transistors 36 and 40, respectively. Drains of the first and third transistors 34 and 38, respectively, communicate and sources of the second and fourth transistors 36 and 40, respectively, communicate.

#First and second inductors 42 and 44, respectively, form a coupled inductor circuit 46. A first end of the first inductor 46 communicates with the source of the third transistor 38 and the drain of the fourth transistor 40. A first end of the second inductor 44 communicates with the source of the first transistor 34 and the drain of the second transistor 36. Second ends of the first and second inductors 42 and 44, respectively, communicate. A first end of a capacitor 48 communicates with the second ends of the first and second inductors 42 and 44, respectively.