Method and circuit for controlling the charge of a bootstrap capacitor in a switching step-down regulator
First Claim
1. A method of controlling the charging of a bootstrap capacitance of a switching regulator of a power regulator, the power regulator including a switch that is disposed between a driver and the switching regulator, the method comprising the steps of:
- comparing, at each switching cycle of the power regulator, a voltage of the bootstrap capacitance and a predetermined threshold voltage; and
disabling operation of the switching regulator when the voltage of the bootstrap capacitance is lower than the threshold voltage.
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Accused Products
Abstract
A method of controlling the charging of a bootstrap capacitance incorporated into a switching regulator of a power transistor includes the steps of comparing, at each switching cycle, the voltage value at the bootstrap capacitance and a predetermined threshold voltage, to change the mode of operation of the regulator following said comparison. More particularly, the control on the transistor is taken off the regulator when the voltage at the bootstrap capacitance is lower than the threshold voltage, while the transistor is forced into the "on" state through a full cycle. In this way, the minimum current to operate the regulator can be minimised.
15 Citations
20 Claims
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1. A method of controlling the charging of a bootstrap capacitance of a switching regulator of a power regulator, the power regulator including a switch that is disposed between a driver and the switching regulator, the method comprising the steps of:
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comparing, at each switching cycle of the power regulator, a voltage of the bootstrap capacitance and a predetermined threshold voltage; and disabling operation of the switching regulator when the voltage of the bootstrap capacitance is lower than the threshold voltage. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A method of controlling the charging of a bootstrap capacitance of a switching regulator, the switching regulator comprising a switch that is disposed between a driver and the switching regulator, the method comprising the steps of:
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comparing, at each switching cycle of the switching regulator, a voltage of the bootstrap capacitance and a predetermined threshold voltage; selecting one of a plurality of modes of operation of the switching regulator in response to a relative relationship between the voltage of the bootstrap capacitance and the predetermined threshold voltage; and disabling operation of the switching regulator responsive to the selected one of the plurality of modes of operation. - View Dependent Claims (8, 9, 10, 11)
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12. A circuit for controlling the charging of a bootstrap capacitance incorporated into a switching regulator, the switching regulator further comprising a switch disposed between a driver and a bootstrap capacitance, the circuit comprising:
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a comparator, coupled to the bootstrap capacitance and to a threshold voltage to provide an indication that a voltage across the bootstrap capacitance is less than the threshold voltage; a selector to select between a first switching signal provided by the driver and a second switching signal provided by the circuit responsive to the indication from the comparator. - View Dependent Claims (13, 14, 15)
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16. A power regulating system for providing a voltage to a load during a plurality of switching cycles, the switching regulator comprising:
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a driver to provide a first switching signal; a switching regulator, coupled to the driver by a switch, the switching regulator further comprising; a bootstrap capacitor disposed between a voltage generator and a load; a circuit, coupled to control the switch, for comparing a voltage across the bootstrap capacitor against a threshold voltage to determine a mode of operation of the power regulator, the circuit including; a comparator, coupled to the bootstrap capacitance and to a threshold voltage to provide an indication that a voltage across the bootstrap capacitance is less than the threshold voltage, and a selector to select between the first switching signal provided by the driver and a second switching signal provided by the circuit responsive to the indication from the comparator. - View Dependent Claims (17)
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18. A power regulating system for providing a voltage to a load during a plurality of switching cycles, the switching regulator comprising:
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a driver; a switching regulator, coupled to the driver by a switch, the switching regulator further comprising; a bootstrap capacitor disposed between a voltage generator and a load; means for controlling the switch such that the switch is engaged to couple the driver to the switching regulator only for those switching cycles wherein the voltage across the bootstrap capacitor is less than a threshold voltage. - View Dependent Claims (19, 20)
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Specification