US 7,352,160 B2Granted

Step-down switching regulator

AssigneeRicoh Company, Ltd.

InventorsShinya Shimizu, Masahiro Matsuo

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Abstract

A step-down switching regulator is disclosed that includes a first switching element, a smoothing circuit part including an inductor and a second switching element for synchronous rectification, a switching controller circuit part, and a reverse current detector circuit part that detects a reverse current flowing from the inductor to the second switching element and interrupts the reverse current by causing the switching controller circuit part to turn off the second switching element upon detection of the reverse current. Detecting a change in a set voltage, the reverse current detector circuit part stops, for a predetermined period of time, the operation of causing the switching controller circuit part to turn off the second switching element due to detection of the reverse current, and after the predetermined period of time is over, causes the switching controller circuit part to turn off the second switching element upon detection of the reverse current.

Claims5

Dependent claims

A synchronous-rectification step-down switching regulator capable of changing an output voltage, comprising:

a first switching element configured to switch in accordance with a first control signal input to a control electrode thereof so as to perform output control of an input voltage;
an inductor connected between an output end of the first switching element and an output terminal;
a second switching element for synchronous rectification configured to release energy stored in the inductor in accordance with a second control signal input to a control electrode thereof;
a switching controller circuit part configured to control switching of the first switching element, and cause the second switching element to perform switching opposite to the switching of the first switching element;
a comparator circuit configured to compare a reference voltage to a divided voltage corresponding to said output voltage;
and
a reverse current detector circuit part configured to detect a reverse current flowing from the inductor to the second switching element,
wherein when said comparator circuit detects no change in the reference voltage, the reverse current detector circuit part, upon detection of generation of the reverse current, outputs a control signal to the switching controller circuit part so as to turn off the second switching element for synchronous rectification, and when said comparator circuit detects a change in said reference voltage compared with said divided voltage, the reverse current detector circuit part stops, for a predetermined period of time, the switching controller circuit part from turning off the second switching element even if the reverse current detector circuit part detects the reverse current.

5 more elements

A synchronous-rectification step-down switching regulator capable of changing an output voltage, comprising:

a first switching element configured to switch in accordance with a first control signal input to a control electrode thereof so as to perform output control of an input voltage;
an inductor connected between an output end of the first switching element and an output terminal;
a second switching element for synchronous rectification configured to release energy stored in the inductor in accordance with a second control signal input to a control electrode thereof;
a switching controller circuit part configured to control switching of the first switching element, and cause the second switching element to perform switching opposite to the switching of the first switching element;
and
a reverse current detector circuit part configured to detect a reverse current flowing from the inductor to the second switching element, and interrupt the reverse current by causing the switching controller circuit part to turn off the second switching element upon detection of the reverse current,
wherein upon detection of a change in a reference voltage compared with a divided voltage of the output voltage, the reverse current detector circuit part stops, for a predetermined period of time, the operation of causing the switching controller circuit part to turn off the second switching element due to detection of the reverse current, and after the predetermined period of time is over;
the reverse current detector circuit part causes the switching controller circuit part to turn off the second switching element upon detection of the reverse current,
wherein the switching controller circuit part and the reverse current detector circuit part are formed on a single semiconductor chip so as to form a single IC.

6 more elements

Dependencies are inferred from the claim text.

Facts

Application: 11/634,711Filed 5 Dec 2006 · continuation
Priority: JP 2005-07751417 Mar 2005
Published: US 2007/0075697 A15 Apr 2007
Granted: 1 Apr 2008
Term ends: Not estimatedThe source records don’t support an estimate.

Classification7 codes

H02M 3/1588
Including plural semiconductor devices as final control devices for a single load: comprising at least one synchronous rectifier element
H02M 3/157
With automatic control of output voltage or current, e.g. switching regulators: with digital control
H02M 1/0009
Details of control, feedback or regulation circuits: devices or circuits for detecting current in a converter
H02M 1/0025
Details of control, feedback or regulation circuits: arrangements for modifying reference values, feedback values or error values in the control…

Family

Application11/378,741Parent of this continuation · filed 16 Mar 2006
US 2007/0075697 A1Pre-grant publication · published 5 Apr 2007
US 7,166,993 B2Parent of this continuation
US 2006/0208717 A1Published application
US 7,352,160 B2This patent

From the US filing history. Foreign family members aren’t listed.