Inductive current sensing for DC-DC converter
AssigneeDialog Semiconductor (UK) Limited
InventorsFrancesco Paolo, Julian Tyrrell
Life of this patent
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Abstract
An inductive current sensing method for a DC-DC switching converter is described. A sense coil is placed adjacent to a PCB track between the switching converter output and a load powered by the switching converter. A change in a magnetic field is measured around the track, generating a voltage proportional to a change in a load current. The load current is subtracted from an inductor current, when a current needed on the switching converter output is higher than a current in a steady state. In this way, output voltage undershoot or overshoot in the DC-DC switching converter is minimized.
Claims19
A DC-DC switching converter, including a multiple output switching converter, comprising:
- A sense coil, configured to measure a change in a magnetic field around a PCB track, and to generate a voltage proportional to a change in a load current, built on top of said PCB track between an output of said switching converter and said load powered by said switching converter, and placed after an LC filter, in order to detect a load current slew rate for the switching converter;
- a load current compensation circuit, configured to minimize an undershoot or an overshoot voltage on the switching converter output, using said sense coil;
- wherein said load current compensation circuit is configured to calculate a difference between a sense coil current and said load current using a scaled voltage replication of a load current profile.
A sense coil, in a DC-DC switching converter, comprising:
- a current carrying conductor, further comprising:
- a PCB trace and vertical via holes, on a multilayer board;
- wherein the sense coil is air-cored and constructed around a vertical via hole, connecting two layers in the PCB trace, when the PCB trace changes layers in the multilayer board;
- wherein the sense coil is built on top of the PCB trace, between the DC-DC switching converter and a load;
- and
- wherein a plurality of said vertical via holes are connected in parallel with a central plate, to minimize an inner radius of the sense coil, and are connected to minimize a distance between the inner radius of the sense coil and a source of a magnetic field.
An inductive current sensing method for a DC-DC switching converter, having a control loop implemented with a sense coil, comprising:
- building the sense coil on top of a PCB track between the switching converter output and a load powered by the switching converter;
- placing the sense coil after an LC filter, in order to detect a load current slew rate for the switching converter;
- measuring a change in a magnetic field around the track, and generating a voltage proportional to a change in a load current using the sense coil;
- calculating a difference between a sense coil current and the load current using a scaled voltage replication of a load current profile;
- subtracting the load current from said sense coil current, when a current needed on the switching converter output is higher than a current in a steady state;
- and
- minimizing an undershoot or overshoot in the DC-DC switching converter.
Dependencies are inferred from the claim text.