US 8,427,121 B2 · Multi-output DC-DC converter

Abstract

A DC-to-DC converter generates multiple outputs from a single input supply using a single inductor. The inductor current can be changed rapidly by connecting the input voltage in either direction across the inductor using switches A to F. In use, current flows from the input supply through the inductor to an output during a charge phase, then current flows from ground through the inductor to the output in a discharge phase. The level of inductor current at the end of the discharge phase is stored. Before the next charge phase for the same output, the input supply is connected across the inductor in a slew phase to bring the inductor current to the stored level. This reduces crosstalk between outputs having different power requirements. Variable frequency noise in the converter is reduced by giving each output the same total time (slew phase+charge phase+discharge phase).

Claims34

Dependent claims

A method of controlling a dc-to-dc electric power supply circuit in which the current through an inductor is used to supply electric power to respective ones of a plurality of outputs during successive respective time periods,

the method comprising:
(i) in at least some of said time periods,
(a) a current correction step;
and
(ii) during each said time period:
(b) a first power supply step during which electric power is supplied to the inductor from a dc power source and current from the inductor is supplied to the respective output;
and
(c) a second power supply step, subsequent to the first power supply step, in which current from the inductor is supplied to the respective output while electric power is not supplied to the inductor,
wherein:
in each of said time periods wherein a current correction step occurs, the first power supply step is subsequent to the current correction step;
the level of current in the inductor at the end of the second power supply step is detected and stored;
and
the current correction step is a step in which the level of current in the inductor is altered in the direction to reduce the difference between the level of current in the inductor and the said stored level of current at the end of the second power supply step in the most recent previous said time period for the same output.

10 more elements

A dc-to-dc electric power supply circuit comprising:

an inductor;
a plurality of outputs;
an input for receiving electric power from a dc power source;
a switching arrangement for selectively connecting the input to the inductor and disconnecting the input therefrom, and for selectively connecting the inductor to respective ones of the outputs at respective times and disconnecting the inductor therefrom;
a detecting arrangement for detecting the level of current in the inductor;
and
control circuitry for receiving the detected level from the detecting arrangement and for controlling the switching arrangement,
the control circuitry being arranged to control the switching arrangement so that the current through the inductor is supplied to respective ones of the plurality of outputs during successive respective time periods, at least some of said time periods comprising a current correction phase and each said time period comprising a first power supply phase and a second power supply phase subsequent to the first power supply phase, and in each of said time periods that comprises a current correction phase, the first power supply phase is subsequent to the current correction phase:
wherein
the control circuitry is arranged to store the level of current in the inductor detected by the detecting arrangement at the end of the second power supply phase and
(a) the control circuitry is arranged to control the switching arrangement during the current correction phase so as to alter the level of current in the inductor in the direction to reduce the difference between the level of current in the inductor and the said stored level of the current detected at the end of the second power supply phase in the most recent previous said time period for the same output,
(b) the control circuitry is arranged to control the switching arrangement during the first power supply phase to connect the input to the inductor to supply electric power to the inductor from a dc power source, and to connect the inductor to the respective output so as to supply current from the inductor to the respective output, and
(c) the control circuitry is arranged to control the switching arrangement during the second power supply phase to connect the inductor to the respective output so as to supply current from the inductor to the respective output and to disconnect the input from the inductor so that electric power is not supplied to the inductor.

10 more elements

Dependencies are inferred from the claim text.

Multi-output DC-DC converter

Life of this patent

Multi-output DC-DC converter

Life of this patent

Abstract

Claims34