Back to results
US 5,204,550 AGranted
Output stage having reduced current consumption
AssigneeTexas Instruments Deutschland GmbH
InventorHorst Jungert
Life of this patent
Estimating the term…
Abstract
An output stage for a digital circuit for emitting a signal with the one or the other binary value in dependence upon an input signal includes an output transistor at the collector of which the signal to be emitted can be tapped off and to the base of which a current dependent on the input signal is supplied. In the line leading to the base of the output transistor, a device is disposed for setting the base current in dependence upon the current flowing through the collector-emitter path of the output transistor.
Claims6
A digital output circuit comprising:
- an input terminal for receiving a binary input signal;
- an output terminal for providing a binary output signal;
- a power source terminal for providing a supply voltage;
- a bipolar output transistor having a collector, an emitter and a base;
- the collector of said bipolar output transistor being connected to said output terminal and to said power source terminal, the emitter of said bipolar output transistor being connected to ground, and the base of said bipolar output transistor being connected to said power source terminal;
- means operably connected to said output terminal for generating a control signal having a magnitude dependent upon the magnitude of the voltage at the output terminal;
- a first field-effect transistor connected between said power source terminal and the base of said bipolar output transistor and having a control gate connected to said input terminal;
- a resistor interposed between said first field-effect transistor and the base of said bipolar output transistor and respectively connected thereto;
- and
- a second field-effect transistor having a source-drain path connected in parallel with said resistor and a control gate connected to said control signal-generating means, the control gate of said second field-effect transistor being responsive to the control signal at a magnitude equal to or above a predetermined threshold to render said second field-effect transistor conductive for decreasing the resistance value of said resistor to enable the base current applied to the base of said bipolar output transistor to increase, thereby rendering said bipolar output transistor conductive.
7 more elements
A digital output circuit comprising:
- an input terminal for receiving a binary input signal;
- an output terminal for providing a binary output signal;
- a power source terminal for providing a supply voltage;
- a bipolar output transistor having a collector, an emitter and a base;
- the collector of said bipolar output transistor being connected to said output terminal and to said power source terminal, the emitter of said bipolar output transistor being connected to ground, and the base of said bipolar output transistor being connected to said power source terminal;
- means operably connected to said output terminal for generating a control signal having a magnitude dependent upon the magnitude of the voltage at the output terminal;
- a variable current source connected between the output of said control signal-generating means and the base of said bipolar output transistor and having a current output magnitude dependent upon the control signal as output by said control signal-generating means;
- and
- said bipolar output transistor being rendered conductive in response to the voltage at said output terminal being at a level enabling said control signal-generating means to generate a control signal at a magnitude equal to or above a predetermined threshold such that said variable current source provides a base current to the base of said bipolar output transistor in response to the control signal from said control signal-generating means of increased magnitude enabling current to flow from said output terminal through the collector-emitter path of said bipolar output transistor.
- wherein said digital output circuit further includes a reference voltage source for providing a reference voltage connected to said control signal-generating means, each of said control signal-generating means and said reference voltage source being connected to said power source terminal;
- said control signal-generating means being responsive to the magnitude of the voltage at said output terminal as compared to the reference voltage provided by said reference voltage source in generating the control signal;
- the control signal being below the predetermined threshold when the voltage at said output terminal is less than the reference voltage from said reference voltage source such that said variable current source provides a first base current to the base of said bipolar output transistor of a relatively low magnitude;
- and
- the control signal being at least equal to said predetermined threshold when the voltage at said output terminal exceeds the reference voltage from said reference voltage source such that said variable current source provides a second base current to the base of said bipolar output transistor of a relatively high magnitude as compared to said first base current.
11 more elements
Dependencies are inferred from the claim text.