Integrated circuit voltage regulator with transient protection
First Claim
1. An integrated circuit voltage regulator which is protected against excessive voltage excursions, comprising:
- a supply terminal for receiving electrical current at a positive voltage which may have substantial superimposed excursions of positive or negative polarity relative to a reference voltage;
a source of the reference voltage;
an NPN regulator pass transistor having base, collector and emitter electrodes, said pass transistor being susceptible to electrical breakdown when positive or negative voltages in excess of first and second predetermined magnitudes respectively are impressed between the collector and base electrodes, the first and second predetermined magnitudes being less than the magnitudes of voltage excursions which may be present at said supply terminal;
first base drive means for supplying a substantially constant voltage to the base electrode of said pass transistor;
a diode having its anode connected to said source of the reference voltage and its cathode connected to the collector electrode of said pass transistor for limiting the positive voltage at the collector electrode to less than the first predetermined magnitude;
a first PNP transistor having base, collector and emitter electrodes, the collector electrode being connected to the collector electrode of said pass transistor;
first connecting means connecting said supply terminal to the emitter of said first PNP transistor; and
second base drive means for supplying a substantially constant current to the base electrode of said first PNP transistor, whereby said first PNP transistor limits the negative voltage applied to the collector electrode of said pass transistor to less than the second predetermined magnitude and limits the current through said diode when it is in electrical breakdown.
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Accused Products
Abstract
A monolithic integrated circuit voltage regulator is disclosed in which a bipolar series pass transistor has both its collector and base electrodes protected from excessive positive and negative supply transients. Protection from positive voltage transients is provided by a reverse biased diode. Protection against negative voltage transients is provided by a bipolar transistor of opposite conductivity type from the pass transistor and a resistor in series therewith. The resistor is a diffused resistor comprising P-type material in an electrically isolated N-type well, resulting in blockage of negative voltage transients by both the transistor and the resistor.
36 Citations
27 Claims
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1. An integrated circuit voltage regulator which is protected against excessive voltage excursions, comprising:
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a supply terminal for receiving electrical current at a positive voltage which may have substantial superimposed excursions of positive or negative polarity relative to a reference voltage; a source of the reference voltage; an NPN regulator pass transistor having base, collector and emitter electrodes, said pass transistor being susceptible to electrical breakdown when positive or negative voltages in excess of first and second predetermined magnitudes respectively are impressed between the collector and base electrodes, the first and second predetermined magnitudes being less than the magnitudes of voltage excursions which may be present at said supply terminal; first base drive means for supplying a substantially constant voltage to the base electrode of said pass transistor; a diode having its anode connected to said source of the reference voltage and its cathode connected to the collector electrode of said pass transistor for limiting the positive voltage at the collector electrode to less than the first predetermined magnitude; a first PNP transistor having base, collector and emitter electrodes, the collector electrode being connected to the collector electrode of said pass transistor; first connecting means connecting said supply terminal to the emitter of said first PNP transistor; and second base drive means for supplying a substantially constant current to the base electrode of said first PNP transistor, whereby said first PNP transistor limits the negative voltage applied to the collector electrode of said pass transistor to less than the second predetermined magnitude and limits the current through said diode when it is in electrical breakdown. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. An integrated circuit voltage regulator with improved protection against excessive voltage excursions, comprising:
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a supply terminal for receiving electrical current at a voltage which may have substantial superimposed excursions of positive or negative polarity relative to a reference voltage; a source of the reference voltage; a bipolar regulator pass transistor of a first conductivity type having a base electrode and first and second additional electrodes, said pass transistor being susceptible to electrical breakdown when positive or negative voltages in excess of first and second predetermined magnitudes respectively are impressed between the base electrode and the first additional electrode, the first and second predetermined magnitudes being less than the magnitudes of the voltage excursions which may be present at said supply terminal; first base drive means for supplying a substantially constant voltage to the base electrode of said pass transistor; a diode connected between said source of the reference voltage and the first additional electrode of said pass transistor for limiting voltage excursions of the first polarity to less than the first predetermined magnitude; a bipolar transistor of a second conductivity type having a base electrode and first and second additional electrodes, the first electrode being connected to the first electrode of said pass transistor; connecting means connecting said supply terminal to the second terminal of said transistor of a second conductivity type; and second base drive means for supplying a substantially constant current to the base of said transistor of the second conductivity type.
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12. An integrated circuit voltage regulator with improved transient protection, comprising:
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an input terminal for receving elecrical current at a voltage which may have substantial superimposed excursions of first or second polarities relative to a reference voltage; a source of the reference voltage; an output terminal for supplying electrical current at a regulated voltage; first and second bipolar transistors of opposite conductivity types, each having a base electrode and first and second additional electrodes; first connecting means connecting said first and second transistors between said input and output terminals through their first an second additional electrodes so that corresponding additional electrodes of said first and second transistors are connected together at a junction and said first transistor is connected to said output terminal; a diode connected between said source of the reference voltage and the junction of said first and second transistors for limiting voltage excursions of the first polarity at the junction to less than the electrical breakdown voltage of said first transistor; and first and second drive means for supplying substantially constant signals to the base electrodes of said first and second transistors respectively. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20, 21)
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22. An integrated circuit voltage regulator which is protected against excessive voltage excursions, comprising:
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a supply terminal for receiving electrical current at a positive voltage which may have substantial superimposed excursions of positive or negative polarity relative to a reference voltage; a source of the reference voltage; an NPN regulator pass transistor having base, collector and emitter electrodes, said pass transistor being susceptible to electrical breakdown when positive or negative voltage in excess of first and second predetermined magnitudes respectively are impressed between the collector and base electrodes, the first and second predetermined magnitudes being less than the magnitude of voltage excursions which may be present at said supply terminal; first base drive means for supplying a substantially constant voltage to the base electrode of said pass transistor; diode means having its anode connected to said source of the reference voltage and its cathode connected to the collector electrode of said pass transistor for limiting the positive voltage at the collector electrode to less than the first predetermined magnitude; a PNP transistor having base, collector and emitter electrodes; first connecting means connecting the collector electrodes of said first PNP transistor and said NPN regulator pass transistor; second connecting means connecting said supply terminal to the emitter of said first PNP transistor; and second base drive means for supplying a substantially constant current to the base electrode of said PNP transistor, whereby said PNP transistor limits the negative voltage applied to the collector electrode of said pass transistor to less than the second predetermined magnitude and limits the current through said diode when it is in electrical breakdown. - View Dependent Claims (23)
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24. An integrated circuit voltage regulator with improved protection against excessive voltage excursions, comprising:
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a supply terminal for receiving electrical current, at a voltage which may have substantial superimposed excursions of positive or negative polarity relative to a reference voltage; a source of the reference voltage; a bipolar regulator pass transistor of a first conductivity type having a base electrode and first and second additional electrodes, said pass transistor being susceptible to electrical breakdown when positive or negative voltages in excess of first and second predetermined magnitudes respectively are impressed between the base electrode and the first additional electrode, the first and second predetermined magnitudes being less than the magnitudes of the voltage excursions which may be present at said supply terminal; first base drive means for supplying a substantially constant voltage to the base electrode of said pass transistor; diode means connected between said source of the reference voltage and the first additional electrode of said pass transistor for limiting voltage excursions of the first polarity to less than the first predetermined magnitude; a bipolar transistor of a second conductivity type having a base electrode and first and second additional electrodes; first connecting means connecting the first electrodes of said bipolar transistors of first and second conductivity types; second connecting means connecting said supply terminal to the second terminal of said transistor of the second conductivity type; and second base drive means for supplying a substantially constant current to the base of said transistor of the second conductivity type.
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25. An integrated circuit voltage regulator with improved transient protection, comprising:
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an input terminal for receiving electrical current at a voltage which may have substantial superimposed excursions of first or second polarities relative to a reference voltage; a source of the reference voltage; an output terminal for supplying electrical current at a regulated voltage; first and second bipolar transistors of opposite conductivity types, each having a base electrode and first and second additional electrodes; first connecting means connecting corresponding first additional electrodes of said first and second transistors to said output and input terminals respectively and providing a connection between the corresponding second additional electrodes of said first and second transistors; a diode connected between said source of the reference voltage and the second additional electrode of said first transistor for limiting voltage excursions of the first polarity at the second additional electrode of said first transistor to less than the electrical breakdown voltage thereof; and first and second drive means for supplying substantially constant signals to the base electrodes of said first and second transistors respectively. - View Dependent Claims (26, 27)
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Specification