Switching regulator
First Claim
1. A switching regulator control circuit for use in a switching regulator that converts an input voltage into an output voltage by switching of a switching device, the switching regulator control circuit generating a switching signal for controlling ON/OFF operation of the switching device, the switching regulator control circuit comprising:
- a fault detector configured to detect, based on a duty ratio of the switching signal or a variable correlated to the duty ratio and included in a control signal used to generate the switching signal, a fault state where the duty ratio falls outside a normal modulation range; and
a fault protector configured to stop the switching of the switching device when the fault detector detects the fault state,whereinan upper limit of a pulse width of the switching signal is limited by a fixed width, andthe fault detector is configured to detect the fault state when n or more pulses with the fixed width occur in the switching signal within m switching periods of normal operation (where m is a natural number other than 0 such that n<
m).
1 Assignment
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Accused Products
Abstract
A switching regulator control circuit is used in a switching regulator that converts an input voltage into an output voltage by the switching of a switching device, and generates a switching signal for controlling the ON/OFF operation of the switching device. The switching regulator control circuit has a fault detector and a fault protector. The fault detector detects, based on the duty ratio of the switching signal or a variable correlated to it and included in a control signal used to generate the switching signal, a fault state where the duty ratio falls outside the normal modulation range. The fault protector stops the switching of the switching device when the fault detector detects a fault state.
12 Citations
22 Claims
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1. A switching regulator control circuit for use in a switching regulator that converts an input voltage into an output voltage by switching of a switching device, the switching regulator control circuit generating a switching signal for controlling ON/OFF operation of the switching device, the switching regulator control circuit comprising:
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a fault detector configured to detect, based on a duty ratio of the switching signal or a variable correlated to the duty ratio and included in a control signal used to generate the switching signal, a fault state where the duty ratio falls outside a normal modulation range; and a fault protector configured to stop the switching of the switching device when the fault detector detects the fault state, wherein an upper limit of a pulse width of the switching signal is limited by a fixed width, and the fault detector is configured to detect the fault state when n or more pulses with the fixed width occur in the switching signal within m switching periods of normal operation (where m is a natural number other than 0 such that n<
m). - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A current-mode-control switching power supply device, comprising:
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a first switch having a first terminal thereof connected to a first application terminal to which an input voltage is applied; a second switch having a first terminal thereof connected to a second terminal of the first switch and having a second terminal thereof connected to a second application terminal to which a voltage lower than the input voltage is applied; a current sensor configured to sense a current through the second switch; an overcurrent sensor configured to sense an overcurrent through the second switch; and a controller configured to control the first and second switches according to the current sensed by the current sensor, wherein the controller includes a slope voltage generator configured to accumulate information on the current sensed by the current sensor during a predetermined period in which the first switch is OFF to generate a slope voltage based on the accumulated information on the current, the controller being configured to control the first and second switches according to the slope voltage, the controller is configured to limit to a fixed width a pulse width of a pulse occurring in a switching signal for controlling ON/OFF operation of the first and second switches if continuing to control the first and second switches according to the slope voltage causes the pulse width of the pulse occurring in the switching signal to exceed the fixed width, and the controller is configured to inhibit any pulse from occurring in the switching signal during a period in which an overcurrent is sensed by the overcurrent sensor and to stop ON/OFF operation of the first switch to turn the first switch OFF when a plurality of pulses with the fixed width are occurring successively in the switching signal at a switching frequency of normal operation. - View Dependent Claims (9, 10, 11, 12, 13)
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14. A switching regulator control circuit for use in a switching regulator including:
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a first switch having a first terminal thereof connected to a first application terminal to which an input voltage is applied; a second switch having a first terminal thereof connected to a second terminal of the first switch and having a second terminal thereof connected to a second application terminal to which a voltage lower than the input voltage is applied; and an overcurrent sensor configured to monitor a potential difference between the first and second terminals of the second switch to sense an overcurrent through the second switch, the switching regulator control circuit generating a switching signal for controlling ON/OFF operation of the first switch, wherein the switching regulator control circuit comprises; a fault detector configured to detect, based on a duty ratio of the switching signal or a variable correlated to the duty ratio and included in a control signal used to generate the switching signal, a fault state where the duty ratio falls outside a normal modulation range; and a fault protector configured to stop the switching of the first switch to turn the first switch OFF when the fault detector detects the fault state, wherein the switching regulator control circuit is configured to limit an upper limit of a pulse width of the switching signal to a fixed width, the switching regulator control circuit is configured to inhibit any pulse from occurring in the switching signal during a period in which an overcurrent is sensed by the overcurrent sensor, and the fault detector is configured to detect the fault state when a plurality of pulses with the fixed width are occurring successively in the switching signal at a switching frequency of normal operation during a continuous period in which no overcurrent is sensed by the overcurrent sensor. - View Dependent Claims (15, 16, 17)
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18. A current-mode-control switching power supply device, comprising:
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a first switch having a first terminal thereof connected to a first application terminal to which an input voltage is applied; a second switch having a first terminal thereof connected to a second terminal of the first switch and having a second terminal thereof connected to a second application terminal to which a voltage lower than the input voltage is applied; a current sensor configured to monitor a potential difference between the first and second terminals of the second switch to sense a current through the second switch; an overcurrent sensor configured to monitor the potential difference between the first and second terminals of the second switch to sense an overcurrent through the second switch; and a controller configured to control the first and second switches according to the current sensed by the current sensor, wherein the controller includes a slope voltage generator configured to accumulate information on the current sensed by the current sensor during a predetermined period in which the first switch is OFF to generate a slope voltage based on the accumulated information on the current, the controller being configured to control the first and second switches according to the slope voltage, the controller includes a switching regulator control circuit, wherein the switching regulator control circuit comprises; a fault detector configured to detect, based on a duty ratio of the switching signal or a variable correlated to the duty ratio and included in a control signal used to generate the switching signal, a fault state where the duty ratio falls outside a normal modulation range; and a fault protector configured to stop the switching of the first switch to turn the first switch OFF when the fault detector detects the fault state, wherein the switching regulator control circuit is configured to limit an upper limit of a pulse width of the switching signal to a fixed width, the switching regulator control circuit is configured to inhibit any pulse from occurring in the switching signal during a period in which an overcurrent is sensed by the overcurrent sensor, and the fault detector is configured to detect the fault state when a plurality of pulses with the fixed width are occurring successively in the switching signal at a switching frequency of normal operation during a continuous period in which no overcurrent is sensed by the overcurrent sensor. - View Dependent Claims (19, 20)
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21. A vehicle-mounted appliance including a switching regulator, wherein
the switching regulator comprises: -
a first switch having a first terminal thereof connected to a first application terminal to which an input voltage is applied; a second switch having a first terminal thereof connected to a second terminal of the first switch and having a second terminal thereof connected to a second application terminal to which a voltage lower than the input voltage is applied; an overcurrent sensor configured to monitor a potential difference between the first and second terminals of the second switch to sense an overcurrent through the second switch; and a controller configured to control the first and second switches, wherein the controller includes a switching regulator control circuit, wherein the switching regulator control circuit comprises; a fault detector configured to detect, based on a duty ratio of the switching signal or a variable correlated to the duty ratio and included in a control signal used to generate the switching signal, a fault state where the duty ratio falls outside a normal modulation range; and a fault protector configured to stop the switching of the first switch to turn the first switch OFF when the fault detector detects the fault state, wherein the switching regulator control circuit is configured to limit an upper limit of a pulse width of the switching signal to a fixed width, the switching regulator control circuit is configured to inhibit any pulse from occurring in the switching signal during a period in which an overcurrent is sensed by the overcurrent sensor, and the fault detector is configured to detect the fault state when a plurality of pulses with the fixed width are occurring successively in the switching signal at a switching frequency of normal operation during a continuous period in which no overcurrent is sensed by the overcurrent sensor. - View Dependent Claims (22)
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Specification