US4060758A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Power switching circuit having a Darlington connected transistor pair
Assignee: ZF International UK Ltd
•
Filing: 1976-05-27
•
Granted: 1977-11-29
•
Expires: 1996-05-27
Abstract
Abstract A switching circuit has an output transistor between an input and an output conductor, and a drive transistor, the transistors being Darlington-connected. A transformer has one winding in the collector circuit of the drive transistor and another winding across the base-emitter junction of the output transistor, the windings being arranged so that a falling collector current to the drive transistor induces a reverse bias current in the base-emitter junction of the output transistor.
Inventors
- 👤 Owen Edgar Wright
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 22:17
CPC Classifications
H; H03; H03K; H03K17/00; H03K17/51; H03K17/56; H03K17/60; H03K17/64; H02; H02M; H02M1/00; H02M1/06; H03K17/04; H03K17/041; H03K17/0412; H03K17/04126
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
114 words
A power switching circuit comprising a first supply conductor, a first output conductor, an output transistor having its collector connected to one conductor and its emitter connected to the other conductor, a drive transistor having its emitter connected to the base of the output transistor and its base connected to a control circuit and a transformer having one winding connecting the collector of the drive transistor to said one conductor and another winding connecting the emitter of the drive transistor to the emitter of the output transistor, the transformer being wound so that falling current in the collector of the drive transistor induces reverse bias current in the base-emitter junction of the output transistor.
Claim 2
Dependent Claim
114 words
A power switching circuit comprising a first supply conductor, a first output conductor, an output transistor having its collector connected to one conductor and its emitter connected to the other conductor, a drive transistor having its emitter connected to the base of the output transistor and its base connected to a control circuit and a transformer having one winding connecting the collector of the drive transistor to said one conductor and another winding connecting the emitter of the drive transistor to the emitter of the output transistor, the transformer being wound so that falling current in the collector of the drive transistor induces reverse bias current in the base-emitter junction of the output transistor.
Claim 3
Dependent Claim
23 words
A circuit as claimed in claim 1 which includes means for limiting the reverse bias at the base-emitter junction of the output transistor.
Claim 4
Dependent Claim
37 words
A circuit as claimed in claim 2 in which said reverse-bias limiting means comprises two diodes connected back to back between the base and emitter of said output transistor, one of said diodes being a zener diode.
Claim 5
Dependent Claim
31 words
A circuit as claimed in claim 1 which includes control means, responsive to the voltage on said output conductor, for supplying a pulsed output to the base of said drive transistor.
Claim 6
Dependent Claim
34 words
A circuit as claimed in claim 4 which includes a second input conductor, a second output conductor connected to said second input rail, and a capacitor connected between said first and second output rails.
Claim 7
Dependent Claim
19 words
A circuit as claimed in claim 5 which includes an inductor interconnecting said second input and second output conductor.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1980-11-28 | 1981-05-30 | 1981-11-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-11-28 | 1985-05-30 | 1985-11-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-11-28 | 1989-05-30 | 1989-11-29 | $7700.00 | Window Closed / Lapsed |