Transistor base current regulator
First Claim
1. The combination comprising:
- first and second power terminals for the application therebetween of an input voltage (VIN);
an output terminal;
means for the connection of a load means between said output terminal and said second power terminal;
a selectively enabled transistor switch having a collector and an emitter defining the ends of its main conduction path and a base for the application thereto of base drive;
means connecting the collector-to-emitter path of said transistor switch between said first power terminal and said output terminal; and
controllable base drive means coupled between the base of said transistor switch and said second power terminal for supplying base drive to said transistor switch and causing an amplified current to flow between its collector and emitter, said controllable base drive means including sensing means coupled to the emitter and collector of said transistor switch for sensing when the voltage between the collector and the emitter is less than a predetermined value as a result of excessive base drive and for then reducing the base current flowing in the base of said transistor switch.
4 Assignments
0 Petitions
Accused Products
Abstract
The collector-to-emitter voltage (VCE) of a transistor switch and its base drive are designed to have maximum specified values when the transistor switch conducts the highest specified load current. The base drive to the transistor switch is reduced when the load current is reduced, or when the beta of the transistor increases or is greater than a minimum specified value. The base drive to the transistor switch is regulated by sensing the VCE of the transistor switch and producing a control current which decreases with decreasing VCE and increases with increasing VCE. The control current is then used to supply a regulated base current to the transistor switch while maintaining the VCE of the transistor below, the maximum specified value, for values of load current below the maximum specified level.
-
Citations
10 Claims
-
1. The combination comprising:
-
first and second power terminals for the application therebetween of an input voltage (VIN); an output terminal; means for the connection of a load means between said output terminal and said second power terminal; a selectively enabled transistor switch having a collector and an emitter defining the ends of its main conduction path and a base for the application thereto of base drive; means connecting the collector-to-emitter path of said transistor switch between said first power terminal and said output terminal; and controllable base drive means coupled between the base of said transistor switch and said second power terminal for supplying base drive to said transistor switch and causing an amplified current to flow between its collector and emitter, said controllable base drive means including sensing means coupled to the emitter and collector of said transistor switch for sensing when the voltage between the collector and the emitter is less than a predetermined value as a result of excessive base drive and for then reducing the base current flowing in the base of said transistor switch. - View Dependent Claims (2)
-
-
3. The combination comprising:
-
first and second power terminals for the application therebetween of an input voltage (VIN); an output terminal; means for the connection of a load means between said output terminal and said second power terminal; a selectively enabled transistor switch having a collector and an emitter defining the ends of its main conduction path and a base for the application thereto of base drive; means connecting the collector-to-emitter path of said transistor switch between said first power terminal and said output terminal; voltage difference sensing means connected between the emitter and collector of said transistor switch for sensing when a difference between a voltage at said emitter and a voltage at said collector of said transistor switch is less than a predetermined value and for producing a control current which decreases as a function of a decrease in said collector-to-emitter voltage below said predetermined value; and current amplifying means coupled between said voltage difference sensing means and the base of said transistor switch for amplifying said control current and supplying said amplified current to the base of said transistor switch. - View Dependent Claims (4, 5, 6, 7, 8, 9)
-
-
10. In a circuit in which the collector-to-emitter path of a transistor switch is connected in series with a load between first and second power terminals for the application therebetween of an operating potential and a means is coupled between the base of said transistor switch and said second power terminal for supplying base drive to said transistor switch and causing a corresponding collector-to-emitter current;
- means for regulating the base drive supplied to said transistor switch as a function of the collector-to-emitter current flowing through said transistor switch, comprising;
voltage difference sensing means connected between the emitter and collector of said transistor switch for sensing a difference between a voltage at the emitter and a voltage at the collector of said transistor switch and for producing a control current which decreases when said collector-to-emitter voltage decreases below a predetermined value; and current amplifying means coupled between said voltage difference sensing means and the base of said transistor switch for amplifying said control current and supplying said amplified current to the base of said transistor switch.
- means for regulating the base drive supplied to said transistor switch as a function of the collector-to-emitter current flowing through said transistor switch, comprising;
Specification