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US 8,410,767 B2Granted
Control circuit of DC-DC converter applying offset to coil current, DC-DC converter applying offset to coil current and control method of DC-DC converter
AssigneeFujitsu Semiconductor Limited
InventorToru Miyamae
Life of this patent
Estimating the term…
Abstract
A DC-DC converter or the like capable of generating a stable output voltage is provided. A control circuit 11 of a current mode step-down DC-DC converter 1 includes a slope compensation circuit SC and an offset circuit IF1. The slope compensation circuit SC adds an increase gradient m2 due to slope compensation to an increase gradient of a coil current waveform Vsense in a range wherein an ON period Ton of a switch SW1 exceeds ½ of an operating cycle T. An offset circuit IF1 applies an offset voltage Voffset which becomes smaller depending on the ON period Ton in excess of ½ of an operating cycle T, to a coil current waveform Vsense.
Claims9
A control circuit of a DC-DC converter comprising:
- a differential amplifier configured to output a differential output in accordance with an output voltage to be outputted through a coil and a reference voltage;
- a first control circuit configured to compare the differential output with a coil current flowing to the coil and to determine an ON period in an operating cycle of a main switching element which is included in a current path of the coil current;
- a slope compensation circuit configured to add an increase gradient due to slope compensation to an increase gradient of the coil current in a range wherein the ON period exceeds a certain period of time;
- and
- an offset circuit configured to apply an offset to the coil current, the offset becoming smaller depending on the ON period in excess of the certain period of time,
- wherein
- the DC-DC converter is a step-down DC-DC converter;
- and
- the offset circuit decreases the offset by a first increase gradient at which the increase gradient due to slope compensation is equal to an absolute value, in a range wherein the ON period exceeds a certain period of time.
6 more elements
A control circuit of the DC-DC converter comprising:
- a differential amplifier configured to output a differential output in accordance with an output voltage to be outputted through a coil and a reference voltage;
- a first control circuit configured to compare the differential output with a coil current flowing to the coil and to determine an ON period in an operating cycle of a main switching element which is included in a current path of the coil current;
- a slope compensation circuit configured to add an increase gradient due to slope compensation to an increase gradient of the coil current in a range wherein the ON period exceeds a certain period of time;
- and
- an offset circuit configured to apply an offset to the coil current, the offset becoming smaller depending on the ON period in excess of the certain period of time,
- wherein
- the DC-DC converter is one of a step-up DC-DC converter and a step-up/step-down DC-DC converter;
- and
- the offset circuit decreases the offset by a second decrease gradient with respect to an increase in the ON period, in a range wherein the ON period does not exceed the certain period of time.
6 more elements
A DC-DC converter comprising:
- a differential amplifier configured to output a differential output in accordance with an output voltage to be outputted through a coil and a reference voltage;
- a first control circuit configured to compare the differential output with a coil current flowing to the coil and to determine an ON period in an operating cycle of a main switching element which is included in a current path of the coil current;
- a slope compensation circuit configured to add an increase gradient due to slope compensation to an increase gradient of a coil current waveform in a range wherein the ON period exceeds a certain period of time;
- and
- an offset circuit configured to apply an offset to the coil current waveform, with the offset becoming smaller depending on the ON period in excess of the certain period of time,
- wherein
- the DC-DC converter is a step-down DC-DC converter;
- and
- the offset circuit decreases the offset by a first increase gradient at which the increase gradient due to slope compensation is equal to an absolute value, in a range wherein the ON period exceeds a certain period of time.
6 more elements
A control method of a DC-DC converter, comprising:
- outputting a differential output in accordance with an output voltage to be outputted through a coil and a reference voltage and comparing the differential output with a coil current flowing to the coil and determining an ON period in an operating cycle of a main switching element which is included in a current path of the coil current;
- adding an increase gradient due to slope compensation to an increase gradient of a coil current waveform in a range wherein the ON period exceeds a certain period of time;
- and
- applying an offset to the coil current waveform, with the offset becoming smaller depending on the ON period in excess of the certain period of time,
- wherein
- the DC-DC converter is a step-down DC-DC converter;
- and
- the applying the offset decreases the offset by a first increase gradient at which the increase gradient due to slope compensation is equal to an absolute value, in a range wherein the ON period exceeds a certain period of time.
5 more elements
Dependencies are inferred from the claim text.