High performance dual section voltage regulator
First Claim
1. A regulator for receiving an input voltage and outputting a regulated output voltage, comprising:
- a switching regulator having a first input and a first output for receiving on the first input the input voltage and providing on the first output a regulated intermediate voltage in accordance with a switching regulator operation, said first output connected to an intermediate node;
a linear regulator having a second input and a second output with a pass element connected therebetween for receiving on said second input said regulated intermediate voltage associated with said intermediate node and for providing to an output node on said second output the regulated output voltage at a predetermined output voltage level by varying the impedance of said pass element in accordance with a linear voltage regulation operation; and
a regulator control for regulating at least said switching regulator to vary the regulated intermediate voltage to a level that is a predetermined intermediate voltage above said predetermined output voltage level to maintain a predetermined differential voltage across said pass element to minimize power dissipation in said pass element, said regulator control comprising;
an intermediate voltage sensor for sensing said regulated intermediate voltage;
a switching regulator control for utilizing said sensed regulated intermediate voltage to control said switching regulator operation to regulate said regulated intermediate voltage to said predetermined intermediate voltage level;
a differential voltage sensor comprising an operational amplifier (op amp) having a first op amp input electrically connected to said intermediate node, a second op amp input electrically connected to said output node, and an op amp output, wherein said op amp is configured for sensing via said first and second op amp inputs the differential voltage across said pass element between said intermediate node and said output node and for generating onto said op amp output an op amp signal indicative of the differential voltage sensed between said intermediate node and said output node; and
an offset control for modifying said predetermined intermediate voltage when said sensed differential voltage indicated by said op amp signal deviates from said predetermined differential voltage such that said sensed differential voltage is maintained substantially constant and the operation of said switching regulator control is dependent upon said sensed differential voltage.
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Abstract
The voltage regulator includes two sections, a switching regulator section (12) for regulating a voltage from an input (10) to an intermediate node (14). This voltage on the intermediate node (14) is then regulated with a linear regulator down to a regulated output voltage on an output node (18). The linear regulator includes a pass transistor (16) that is controlled by a linear regulator control (50). Linear regulator control (50) is operable to sense the voltage across the transistor (16) and perform multiple functions. First, it controls the pass element transistor (16) to regulate the voltage from the node (14) to the node (18) in a linear manner. Second, it controls the switching regulator section (12) to provide a regulated voltage on the node (14). Third, it controls the level of the voltage on the intermediate node (14) such that it is at a predetermined voltage level above the voltage on the output node (18), such that the power dissipation through the pass element transistor (16) is minimized.
115 Citations
12 Claims
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1. A regulator for receiving an input voltage and outputting a regulated output voltage, comprising:
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a switching regulator having a first input and a first output for receiving on the first input the input voltage and providing on the first output a regulated intermediate voltage in accordance with a switching regulator operation, said first output connected to an intermediate node; a linear regulator having a second input and a second output with a pass element connected therebetween for receiving on said second input said regulated intermediate voltage associated with said intermediate node and for providing to an output node on said second output the regulated output voltage at a predetermined output voltage level by varying the impedance of said pass element in accordance with a linear voltage regulation operation; and a regulator control for regulating at least said switching regulator to vary the regulated intermediate voltage to a level that is a predetermined intermediate voltage above said predetermined output voltage level to maintain a predetermined differential voltage across said pass element to minimize power dissipation in said pass element, said regulator control comprising; an intermediate voltage sensor for sensing said regulated intermediate voltage; a switching regulator control for utilizing said sensed regulated intermediate voltage to control said switching regulator operation to regulate said regulated intermediate voltage to said predetermined intermediate voltage level; a differential voltage sensor comprising an operational amplifier (op amp) having a first op amp input electrically connected to said intermediate node, a second op amp input electrically connected to said output node, and an op amp output, wherein said op amp is configured for sensing via said first and second op amp inputs the differential voltage across said pass element between said intermediate node and said output node and for generating onto said op amp output an op amp signal indicative of the differential voltage sensed between said intermediate node and said output node; and an offset control for modifying said predetermined intermediate voltage when said sensed differential voltage indicated by said op amp signal deviates from said predetermined differential voltage such that said sensed differential voltage is maintained substantially constant and the operation of said switching regulator control is dependent upon said sensed differential voltage. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A method for providing a regulated output voltage from an input voltage, comprising the steps of:
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providing a switching regulator; inputting the input voltage to the switching regulator to provide a regulated intermediate voltage on an output thereof; connecting the output of the switching regulator to an intermediate node to provide the regulated intermediate voltage thereon; providing a linear regulator with a pass element having a series impedance associated therewith and connecting the pass element between the intermediate node and an output node and controlling the pass element to regulate the voltage on the output node to provide the regulated output voltage on the output node at a predetermined output voltage level; and controlling the switching regulator to vary the regulated intermediate voltage to a level that is a predetermined intermediate voltage above the regulated output voltage to maintain a predetermined differential voltage across the pass element to minimize power dissipation in the pass element, the controlling operation being dependent upon the actual differential voltage across the pass element, wherein the controlling operation comprises; sensing the regulated intermediate voltage on the intermediate node; controlling the switching regulator operation to regulate the regulated intermediate voltage to provide an absolute value for the regulated intermediate voltage; providing an operational amplifier (op amp) having a first op amp input electrically connected to said intermediate node, a second op amp input electrically connected to said output node, and an op amp output; sensing via said first and second op amp inputs the differential voltage across said pass element between said intermediate node and said output node; generating onto said op amp output an op amp signal indicative of the differential voltage sensed between said intermediate node and said output node; and modifying the absolute value of the regulated intermediate voltage when the sensed differential voltage deviates from the predetermined differential voltage such that the sensed differential voltage is maintained substantially constant through control of the switching regulator. - View Dependent Claims (8, 9, 10, 11, 12)
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Specification