Base drive circuit
AssigneeHughes Aircraft Company
InventorJohn J. Nesler
Life of this patent
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Abstract
The invention includes a first switching transistor which is actuated by a logic signal. This switching transistor is disposed in a current path from the base of the power transistor. When this switch is actuated, the invention provides a large steady state base drive current superimposed with a base current peaking pulse from a current generator. The invention also includes a second switch which applies a reverse potential to the base of the switching transistor for fast turnoff. The specific embodiments disclose circuitry for regulating forward base drive current to minimize line voltage variations and component tolerances. An improved bipolar power transistor base drive circuit for switching regulator and DC to DC converter power supplies is disclosed.
Claims16
In a power supply having a power transistor with at least three terminals and means for sensing the output at the first terminal thereof, a circuit for providing forward and reverse base drive for the power transistor comprising:
- first switching means coupled to the means for sensing the output of the power transistor for selectively closing a direct current path from a second terminal of the power transistor to a first terminal to provide forward base drive therefor;
- current regulating means in said direct current path for minimizing the effect of variations in the potential applied at the second terminal of the power transistor;
- and
- second switching means coupled to said current path and a source of potential energy for applying said source of potential energy to the second terminal of the power transistor to provide reverse base drive therefor.
A power switch drive circuit for providing forward and reverse base drive including:
- first switching means for providing base drive, said first switching means including a transistor operativedly coupled to means for sensing the output of said power switch;
- and
- second switching means for providing reverse base drive, said second means including a second switching transistor operatively coupled to sense the current flows through said first switching transistor, a capacitor, and means for setting the charge on said capacitor such that said charge on said capacitor is applied by said second switching means to the base of said power transistor.
Dependencies are inferred from the claim text.