US4789842A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Composite transistor device with over-current protection
Assignee: Individual
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Filing: 1987-11-23
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Granted: 1988-12-06
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Expires: 2007-11-23
Abstract
Abstract A composite transistor device having over-current protection is disclosed, and particularly a device for protecting Darlington configuration power transistor devices. The over-current protection circuit operates to clamp the base-emitter potential of the exciter transistor thus causing the power output transistor to maintain a power output below a predetermined threshold value. This allows the control of the power output intensity so as to avoid damage to the circuit, and with a minimum of power losses due to active voltage losses.
Inventors
- 👤 Jiri Naxera
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 01:11
CPC Classifications
H; H03; H03K; H03K17/00; H03K17/08; H03K17/082; H03K17/0826; H03K17/51; H03K17/56; H03K17/60; H03K17/615
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
310 words
A composite transistor device having over-current protection comprising: (a) a sensing resistor having a first resistor electrode and a second resistor electrode; (b) a power output transistor means having an emitter electrode, a base electrode and a collector electrode; (c) an auxiliary transistor being of opposite conductivity type to said power output transistor means and having an emitter electrode and a base electrode for detecting an over-current condition in said composite transistor device, and having a collector electrode for providing a signal means indicative of said over-current condition; (d) an exciter transistor being of opposite conductivity type to that of said power output transistor means and having an emitter electrode, a base electrode and a collector electrode, where said collector electrode of said power output transistor means, said first resistor electrode and said base electrode of said auxiliary transistor are interconnected, and where said second resistor electrode, said emitter electrode of said auxiliary transistor and said emitter electrode of said exciter transistor are interconnected, and where said base electrode of said power output transistor means and said collector electrode of said exciter transistor are interconnected, and where said base electrode of said exciter transistor and said collector electrode of said auxiliary transistor are interconnected so as to clamp the base-emitter potential of said exciter transistor and whereby said device provides: for a detecting means for detecting said over-current condition, said over-current condition being manifested when the collector current flow of said power output transistor means flowing through said sensing resistor exceeds a predetermined value, thus triggering said signal means indicative of said over-current condition; for a clamping means for clamping the base-emitter potential of said exciter transistor in response to said signal means; and for a current flow limiting means for limiting the collector current flow of said power output transistor means to a value less than said predetermined value.
Claim 2
Dependent Claim
310 words
A composite transistor device having over-current protection comprising: (a) a sensing resistor having a first resistor electrode and a second resistor electrode; (b) a power output transistor means having an emitter electrode, a base electrode and a collector electrode; (c) an auxiliary transistor being of opposite conductivity type to said power output transistor means and having an emitter electrode and a base electrode for detecting an over-current condition in said composite transistor device, and having a collector electrode for providing a signal means indicative of said over-current condition; (d) an exciter transistor being of opposite conductivity type to that of said power output transistor means and having an emitter electrode, a base electrode and a collector electrode, where said collector electrode of said power output transistor means, said first resistor electrode and said base electrode of said auxiliary transistor are interconnected, and where said second resistor electrode, said emitter electrode of said auxiliary transistor and said emitter electrode of said exciter transistor are interconnected, and where said base electrode of said power output transistor means and said collector electrode of said exciter transistor are interconnected, and where said base electrode of said exciter transistor and said collector electrode of said auxiliary transistor are interconnected so as to clamp the base-emitter potential of said exciter transistor and whereby said device provides: for a detecting means for detecting said over-current condition, said over-current condition being manifested when the collector current flow of said power output transistor means flowing through said sensing resistor exceeds a predetermined value, thus triggering said signal means indicative of said over-current condition; for a clamping means for clamping the base-emitter potential of said exciter transistor in response to said signal means; and for a current flow limiting means for limiting the collector current flow of said power output transistor means to a value less than said predetermined value.
Claim 3
Dependent Claim
20 words
A complete transistor device according to claim 1 wherein the power output transistor means comprises a single power output transistor.
Claim 4
Dependent Claim
28 words
A composite transistor device according to claim 1 wherein said power output transistor means comprises a plurality of power output transistors being connected to each other in parallel.
Claim 5
Dependent Claim
17 words
A composite transistor device according to claim 1 wherein said device is formed on an integrated circuit.
Claim 6
Dependent Claim
18 words
A composite transistor device according to claim 4 wherein said integrated circuit is formed on a semiconductor die.
Claim 7
Dependent Claim
191 words
A composite transistor device having over-current protection comprising: (a) a sensing resistor having a first resistor electrode and a second resistor electrode; (b) a power output transistor means having an emitter electrode, a base electrode and a collector electrode; (c) an exciter transistor being of same conductivity type to said power output transistor means and having an emitter electrode, a base electrode and a collector electrode; (d) an auxiliary transistor being of opposite conductivity type to that of said power output transistor means and having an emitter electrode, a base electrode and a collector electrode, said auxiliary transistor being connected so that when said emitter and base electrodes detect an over-current condition in the collector current flow of said power output transistor means, characterized in the current flowing through said sensing resistor exceeding a predetermined value, said collector electrode provides for a signal means indicative of said over-current condition; and (e) a clamping transistor means for clamping the base-emitter potential of said exciter transistor transistor in response to said signal means indicative of said over-current condition, said clamping transistor being of the same conductivity type to said power output transistor means.
Claim 8
Dependent Claim
191 words
A composite transistor device having over-current protection comprising: (a) a sensing resistor having a first resistor electrode and a second resistor electrode; (b) a power output transistor means having an emitter electrode, a base electrode and a collector electrode; (c) an exciter transistor being of same conductivity type to said power output transistor means and having an emitter electrode, a base electrode and a collector electrode; (d) an auxiliary transistor being of opposite conductivity type to that of said power output transistor means and having an emitter electrode, a base electrode and a collector electrode, said auxiliary transistor being connected so that when said emitter and base electrodes detect an over-current condition in the collector current flow of said power output transistor means, characterized in the current flowing through said sensing resistor exceeding a predetermined value, said collector electrode provides for a signal means indicative of said over-current condition; and (e) a clamping transistor means for clamping the base-emitter potential of said exciter transistor transistor in response to said signal means indicative of said over-current condition, said clamping transistor being of the same conductivity type to said power output transistor means.
Claim 9
Dependent Claim
145 words
A composite transistor device according to claim 6 wherein said collector electrode of said power output transistor means, said first resistor electrode and said base electrode of said auxiliary transistor are interconnected, and where said second resistor electrode, said emitter electrode of said auxiliary transistor and said collector electrode of said exciter transistor are interconnected, and where said base electrode of said power output transistor means and said emitter electrode of said exciter transistor are interconnected, and where said collector electrode of said auxiliary transistor and said base electrode of said clamping transistor are interconnected so as to clamp the base-emitter potential of said exciter transistor and where said base electrode of said exciter transistor and said collector electrode of said clamping transistor are interconnected, and where said emitter electrode of said power output transistor and said emitter electrode of said clamping transistor are interconnected.
Claim 10
Dependent Claim
20 words
A composite transistor device according to claim 7 wherein said power output transistor means comprises a single power output transistor.
Claim 11
Dependent Claim
27 words
A composite transistor device according to claim 7 wherein said power output transistor means comprises a plurality of power output transistors connected to each other in parallel.
Claim 12
Dependent Claim
17 words
A composite transistor device according to claim 7 wherein said device is formed on an integrated circuit.
Claim 13
Dependent Claim
18 words
A composite transistor device according to claim 10 wherein said integrated circuit is formed on a semiconductor die.
References Cited (Backward Citations)
US4374364A
Cited
US4321648A
Cited
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