PFM SMPS with quick sudden load change response
AssigneeMitsumi Electric Co., Ltd.
InventorHeisuke Nakashima
Life of this patent
Estimating the term…
Abstract
Disclosed is a switching-mode power supply device which outputs a voltage having a different electrical potential from an input voltage including an inductor, a driving switching element and a control circuit, and the control circuit includes a trigger signal generating circuit which generates and outputs a signal which provides timing to turn the driving switching element on or off, a first timekeeping unit which times a fixed ON period or a fixed OFF period which defines the pulse width of a driving pulse of the driving switching element, a second timekeeping unit which times a minimum OFF period or a minimum ON period of the driving switching element and a sudden load change detection circuit which detects a sudden load change.
Claims7
A switching-mode power supply device which outputs a voltage having a different electrical potential from an input voltage, comprising:
- an inductor connected between a voltage input terminal to which a direct-current voltage is inputted and an output terminal to which a load is connected;
- a driving switching element which intermittently passes a current through the inductor, and
- a control circuit which generates a driving pulse having a constant pulse width of which a frequency changes in accordance with a feedback voltage from an output side to carry out on-off control of the driving switching element and, to define an ON or OFF period of the driving switching element so as not to be equal to or shorter than a predetermined period, wherein
- the control circuit comprises:
- a trigger signal generating circuit which generates and outputs a signal which provides timing to turn the driving switching element on or off;
- a first timekeeping unit which times a fixed ON period or a fixed OFF period which defines the pulse width of a driving pulse of the driving switching element;
- a second timekeeping unit which times a minimum OFF period or a minimum ON period of the driving switching element;
- and
- a sudden load change detection circuit which detects a sudden load change, and
- wherein the driving pulse is generated based on an output from the trigger signal generating circuit, an output of the first timekeeping unit, and an output of the second timekeeping unit, and the pulse width of the driving pulse is extended when the sudden load change detection circuit detects a sudden change in the load.
A switching-mode power supply device which outputs a voltage having a different electrical potential from an input voltage, comprising:
- an inductor connected between a voltage input terminal to which a direct-current voltage is inputted and an output terminal to which a load is connected;
- a driving switching element which intermittently passes a current through the inductor, and
- a control circuit which generates a driving pulse having a constant pulse width of which a frequency changes in accordance with a feedback voltage from an output side to carry out on-off control of the driving switching element and, to define an ON or OFF period of the driving switching element so as not to be equal to or shorter than a predetermined period, wherein
- the control circuit comprises:
- a comparator which compares the feedback voltage and a predetermined reference voltage and outputs a signal which provides timing for turning the driving switching element on or off;
- a first timekeeping unit which times a fixed ON period or a fixed OFF period which defines a pulse width of a driving pulse of the driving switching element;
- a second timekeeping unit which times a minimum OFF period or a minimum ON period of the driving switching element;
- and
- a driving pulse generating circuit which generates and outputs the driving pulse based on an output of the comparator, an output of the first timekeeping unit and an output of the second timekeeping unit,
- wherein the driving pulse generating circuit is configured to extend the pulse width of the driving pulse by canceling the output of the first timekeeping unit using the output of the comparator when the load changes suddenly.
Dependencies are inferred from the claim text.