DC/DC converter with multiple operating modes
First Claim
1. A method for controlling an active operating mode of a DC/DC converter, comprising:
- defining a first operating mode and a second operating mode of the DC/DC converter, wherein the first operating mode is characterized by a first switching loss and the second operating mode is characterized by a second switching loss, wherein the first switching loss is less than the second switching loss;
monitoring a coil current, wherein the coil current flows through a predefined coil of the DC/DC converter; and
switching the active operating mode of the DC/DC converter between the first operating mode and the second operating mode in response to the coil current reaching a first predetermined threshold,wherein the coil current is monitored by using a current sense resistor and a hysteresis comparator.
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Abstract
A comparator monitors an output voltage Vout. When an output voltage Vout decreases to a predetermined output voltage or less, the comparator sends a signal that represents this state to a controlling circuit. When the controlling circuit receives the signal, it causes a switching device to be turned on. Thus, a coil current IL is increased. A hysteresis (window) comparator monitors the coil current IL. When the coil current IL reaches a comparison current ILP, the controlling circuit causes the switching device to be turned off. When the coil current IL decreases to the comparison current ILB (where ILP >ILB), the controlling circuit references an output signal of the comparator. When the output voltage Vout is lower than the predetermined output voltage, the controlling circuit causes the switching device to be turned on.
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Citations
29 Claims
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1. A method for controlling an active operating mode of a DC/DC converter, comprising:
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defining a first operating mode and a second operating mode of the DC/DC converter, wherein the first operating mode is characterized by a first switching loss and the second operating mode is characterized by a second switching loss, wherein the first switching loss is less than the second switching loss; monitoring a coil current, wherein the coil current flows through a predefined coil of the DC/DC converter; and switching the active operating mode of the DC/DC converter between the first operating mode and the second operating mode in response to the coil current reaching a first predetermined threshold, wherein the coil current is monitored by using a current sense resistor and a hysteresis comparator. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. A method for controlling an active operating mode of a DC/DC converter, wherein the active operating mode is switchable between a first predefined operating mode and a second predefined operating mode, wherein the first predefined operating mode is characterized by a first switching loss and the second predefined operating mode is characterized by a second switching loss, wherein the first switching loss is less than the second switching loss, comprising:
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monitoring a coil current and an output voltage; and switching the active operating mode of the DC/DC converter from the first operating mode to the second operating mode in response to the coil current crossing of a first predetermined threshold, a lapse of a prescribed delay after the coil current crossing of the first predetermined threshold, and the output voltage being below a predetermined voltage threshold value; wherein the coil current flows through a predefined coil of the DC/DC converter; wherein the coil current, in at least the first operating mode, is characterized by an uninterrupted cycle in which the coil current increases monotonically from the first predetermined threshold to a maximum value, and then decreases monotonically until a next cycle is begun; and wherein the coil current is monitored by using a current sense resistor and a hysteresis comparator.
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17. A method for controlling an active operating mode of a DC/DC converter, wherein the active operating mode is switchable between a first predefined operating mode and a second predefined operating mode, wherein the first predefined operating mode is characterized by a first switching loss and the second predefined operating mode is characterized by a second switching loss, wherein the first switching loss is less than the second switching loss, comprising:
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monitoring a coil current and an output voltage; and switching the active operating mode of the DC/DC converter from the second operating mode to the first operating mode in response to the coil current crossing of a first predetermined threshold, a lapse of a prescribed delay after the coil current crossing of the first predetermined threshold, and the output voltage being above a predetermined voltage threshold value; wherein the coil current flows through a predefined coil of the DC/DC converter; wherein the prescribed delay is resettable in accordance with a comparison between the coil current and a second predetermined threshold value; and wherein the coil current is monitored by using a current sense resistor and a hysteresis comparator.
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18. A DC/DC converter having an active operating mode that is switchable between a first predefined operating mode and a second predefined operating mode, wherein the first predefined operating mode is characterized by a first switching loss and the second predefined operating mode is characterized by a second switching loss, wherein the first switching loss is less than the second switching loss, the converter comprising:
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an input terminal for receiving an input voltage and an input current; an output terminal for providing an output voltage and an output current to a load; a control circuit; a switching device operatively coupled to the control circuit and the input terminal, wherein the switching device is turned on and off by the control circuit; a coil in which a coil current flows when the switching device is in the on state, the coil being operatively coupled to the switching device; and a current sense resistor and a hysteresis comparator for monitoring the coil current and providing a signal to the control circuit to indicate when the voltage across the current sense resistor, as generated by the coil current, is equal a reference value of the hysteresis comparator; wherein the control circuit is responsive to the signal provided in determining when to turn the switching device on or off. - View Dependent Claims (19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29)
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Specification