Manual-adjustment-free controlled-voltage and current-limited D.C. voltage supply
First Claim
Patent Images
1. A constant-voltage and current limited charging circuit, comprising:
- an adjustable voltage regulator having an input terminal, an output terminal and an adjustment terminal;
a current sensing and setting circuit having a first terminal coupled to the output terminal of said adjustable voltage regulator and having a second terminal;
a voltage sensing and output voltage setting circuit having a first terminal coupled to the second terminal of said current sensing and setting circuit and having a second terminal;
a reference voltage source having an output terminal;
an op amp having an inverting input terminal, a non-inverting input terminal and an output terminal, wherein the inverting input terminal is coupled to the second terminal of said voltage sensing and setting circuit, the non-inverting input terminal is coupled to the output terminal of said reference voltage source and the output terminal is coupled to the adjustment terminal of said adjustable voltage regulator, said op amp for setting a voltage at the output terminal of said adjustable voltage regulator at a nominal voltage level, and for maintaining the voltage at the output terminal of said adjustable voltage regulator at the nominal voltage with a precision corresponding to the precision of said reference voltage source; and
a comparator having an inverting input terminal, a non-inverting input terminal and an output terminal, wherein the inverting input terminal is coupled to the adjustment terminal of said adjustable voltage regulator, the non-inverting input terminal is coupled to the second terminal of said current sensing and setting circuit and the output terminal is coupled to the non-inverting input terminal of said op amp, said comparator for sensing the current being drawn from said adjustable voltage regulator, for setting a nominal maximum-current and for preventing the current being drawn from said adjustable voltage regulator from exceeding the nominal maximum current.
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Abstract
Voltage-control and current-limiting negative feedback loops are disclosed that cooperate with an adjustable voltage regulator to provide a constant-amplitude and current-limited D.C. voltage. The regulator and voltage-controlling and current-limiting feedback loops are constituted by low-cost circuit elements that cooperate to provide high-precision voltage and current regulation in a manner that is free from manual adjustment. The circuit of the invention is particularly adapted to charging lead-acid batteries.
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Citations
20 Claims
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1. A constant-voltage and current limited charging circuit, comprising:
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an adjustable voltage regulator having an input terminal, an output terminal and an adjustment terminal; a current sensing and setting circuit having a first terminal coupled to the output terminal of said adjustable voltage regulator and having a second terminal; a voltage sensing and output voltage setting circuit having a first terminal coupled to the second terminal of said current sensing and setting circuit and having a second terminal; a reference voltage source having an output terminal; an op amp having an inverting input terminal, a non-inverting input terminal and an output terminal, wherein the inverting input terminal is coupled to the second terminal of said voltage sensing and setting circuit, the non-inverting input terminal is coupled to the output terminal of said reference voltage source and the output terminal is coupled to the adjustment terminal of said adjustable voltage regulator, said op amp for setting a voltage at the output terminal of said adjustable voltage regulator at a nominal voltage level, and for maintaining the voltage at the output terminal of said adjustable voltage regulator at the nominal voltage with a precision corresponding to the precision of said reference voltage source; and a comparator having an inverting input terminal, a non-inverting input terminal and an output terminal, wherein the inverting input terminal is coupled to the adjustment terminal of said adjustable voltage regulator, the non-inverting input terminal is coupled to the second terminal of said current sensing and setting circuit and the output terminal is coupled to the non-inverting input terminal of said op amp, said comparator for sensing the current being drawn from said adjustable voltage regulator, for setting a nominal maximum-current and for preventing the current being drawn from said adjustable voltage regulator from exceeding the nominal maximum current. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A constant-voltage and current limited charging circuit, comprising:
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an adjustable voltage regulator having an output pin and an adjustment pin; a current sensing and setting resistor having a first terminal coupled to the output terminal of said adjustable voltage regulator and having a second terminal; a voltage divider circuit having a first terminal and a second terminal wherein the first terminal is coupled to the second terminal of said current sensing and setting resistor; a reference voltage circuit for providing at an output terminal a reference voltage having a relatively high precision; an op amp having an inverting input terminal, a non-inverting input terminal and an output terminal wherein the output terminal of said op amp is coupled to the adjustment pin of said adjustable voltage regulator, the non-inverting input terminal of said op amp is coupled to the output terminal of said reference voltage circuit and the inverting input terminal of said op amp is coupled to the second terminal of said voltage divider circuit; and a comparator having an inverting input terminal, a non-inverting input terminal and an output terminal, wherein the output terminal is connected to the non-inverting input terminal of said op amp, the inverting input terminal is connected to the adjustment pin of said adjustable voltage regulator and the non-inverting input terminal is coupled to the second terminal of said current sensing and setting resistor. - View Dependent Claims (12, 13, 14, 15)
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16. A charging circuit comprising:
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an adjustable voltage regulator having an input pin, an output pin and an adjustment pin; a current sensing and setting resistor having a first terminal coupled to the output pin of said voltage regulator and having a second terminal; an op amp having an inverting input terminal, a non-inverting input terminal and an output terminal, wherein the output terminal is coupled to the adjustment pin of said adjustable voltage regulator; a comparator circuit having an inverting input terminal coupled to the adjustment pin of said adjustable voltage regulator, a non-inverting input terminal coupled to the second terminal of said current sensing and setting resistor and an output terminal coupled to the non-inverting input terminal of said op amp; a first resistor having a first terminal and a second terminal, wherein the first terminal of said first resistor is coupled to the second terminal of said current sensing and setting resistor; a second resistor having a first terminal coupled to the second terminal of said first resistor at a first node and to the inverting input terminal of said op amp and having a second terminal coupled to a first reference potential ground; and a reference voltage source having an output terminal coupled to the non-inverting input terminal of said op amp wherein said current sensing and setting resistor, said op amp and said comparator form a current limiting negative feedback circuit coupled to said adjustable voltage regulator and said first resistor, said second resistor, said reference voltage source and said op amp form a constant voltage negative feedback loop coupled to said adjustable voltage regulator. - View Dependent Claims (17, 18, 19, 20)
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Specification