Synchronous-rectified DC to DC converter with improved current sensing
First Claim
1. A power supply, comprising:
- a DC to DC buck pulse width modulator converter circuit having an input, a high side output and a low side output;
a high side switch electrically connected intermediate a common output node and a voltage supply, said high side switch configured for controlling a flow of current therethrough dependent at least in part upon said high side output;
a low side switch electrically connected intermediate said common output node and ground, said low side switch configured for controlling a flow of current therethrough dependent at least in part upon said low side output;
a virtual ground amplifier having a first input, a second input and an output, said second input electrically connected to ground potential;
a current feedback resistor electrically connected intermediate said common output node and said first input of said virtual ground amplifier;
a variable impedance component electrically connected to said output of said virtual ground amplifier and to said first input of said virtual ground amplifier, said variable impedance component configured to vary in impedance dependent at least in part upon said output of said virtual ground amplifier; and
a sample and hold circuit electrically connected intermediate said DC to DC buck pulse width modulator converter circuit and said variable impedance component, said sample and hold circuit configured to source a virtual ground current through said variable impedance component and to sample and hold said virtual ground current.
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Accused Products
Abstract
A DC to DC buck pulse width modulator converter circuit includes an input, a high side output and a low side output. A high side switch is electrically connected between a common output node and a voltage supply, and controls a flow of current therethrough dependent upon the high side output. A low side switch is electrically connected between the common output node and ground, and controls a flow of current therethrough dependent upon the low side output. A virtual ground amplifier includes a second input electrically connected to ground. A current feedback resistor is electrically connected intermediate the common output node and a first input of the virtual ground amplifier. A variable impedance component is electrically connected to an output of the virtual ground amplifier and to the first input of the virtual ground amplifier. The impedance of the variable impedance component is varied dependent upon the output of the virtual ground amplifier. A sample and hold circuit is electrically connected intermediate the input of the pulse width modulator converter circuit and the variable impedance component. The sample and hold circuit sources a virtual ground current through the variable impedance component, and samples the virtual ground current.
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Citations
18 Claims
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1. A power supply, comprising:
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a DC to DC buck pulse width modulator converter circuit having an input, a high side output and a low side output;
a high side switch electrically connected intermediate a common output node and a voltage supply, said high side switch configured for controlling a flow of current therethrough dependent at least in part upon said high side output;
a low side switch electrically connected intermediate said common output node and ground, said low side switch configured for controlling a flow of current therethrough dependent at least in part upon said low side output;
a virtual ground amplifier having a first input, a second input and an output, said second input electrically connected to ground potential;
a current feedback resistor electrically connected intermediate said common output node and said first input of said virtual ground amplifier;
a variable impedance component electrically connected to said output of said virtual ground amplifier and to said first input of said virtual ground amplifier, said variable impedance component configured to vary in impedance dependent at least in part upon said output of said virtual ground amplifier; and
a sample and hold circuit electrically connected intermediate said DC to DC buck pulse width modulator converter circuit and said variable impedance component, said sample and hold circuit configured to source a virtual ground current through said variable impedance component and to sample and hold said virtual ground current. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A method of sensing an output current in a power supply, said power supply comprising a DC to DC buck pulse width modulator converter circuit having an input, a high side output and a low side output, said method comprising the steps of:
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electrically connecting a high side switch intermediate a common output node and a voltage supply, said high side switch configured for controlling a flow of current therethrough dependent at least in part upon said high side output;
a low side switch electrically connected intermediate said common output node and ground, said low side switch configured for controlling a flow of current therethrough dependent at least in part upon said low side output;
directing a sensed current to a virtual ground node, said sensed current comprising a known portion of the output current when said low side switch is in an on condition, said sensed current flowing into said virtual ground node in a first direction;
sourcing a virtual ground current into said virtual ground node, said virtual ground current flowing into said virtual ground node in a second direction, said second direction being opposite to said first direction, said virtual ground current being substantially equal to said sensed current and thereby canceling said sensed current at said virtual ground node; and
sampling and holding a value of said virtual ground current. - View Dependent Claims (13, 14, 15, 16, 17)
comparing said sampled and held value of said virtual ground current to a predetermined maximum limit; and
shutting down said power supply when said virtual ground current exceeds said predetermined maximum limit.
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16. The method of claim 15, comprising the further step of restarting said power supply a predetermined period of time after said shutting down step.
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17. The method of claim 12, comprising the further step of adjusting an output voltage of said power supply dependent at least in part upon said sampled and held value of said virtual ground current.
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18. A power supply, comprising:
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a DC to DC buck pulse width modulator converter circuit having an input, a high side output and a low side output;
a high side switch electrically connected intermediate a common output node and a voltage supply, said high side switch configured for controlling a flow of current therethrough dependent at least in part upon said high side output;
a low side switch electrically connected to said common output node and to ground through a sense resistor, said low side switch configured for controlling a flow of current therethrough dependent at least in part upon said low side output;
a virtual ground amplifier having a first input, a second input and an output, said second input electrically connected to ground potential;
a current feedback resistor electrically connected intermediate said sense resistor and said first input of said virtual ground amplifier;
a variable impedance component electrically connected to said output of said virtual ground amplifier and to said first input of said virtual ground amplifier, said variable impedance component configured to vary in impedance dependent at least in part upon said output of said virtual ground amplifier; and
a sample and hold circuit electrically connected intermediate said DC to DC buck pulse width modulator converter circuit and said variable impedance component, said sample and hold circuit configured to source a virtual ground current through said variable impedance component and to sample and hold said virtual ground current.
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Specification