Low power consumption output driver circuit and supply voltage detection circuit
AssigneeRohm Co., Ltd.
InventorsMasanari Shougomori, Koichi Inoue
Life of this patent
Estimating the term…
Abstract
A semiconductor device has a transistor that controls, according to the resistance of the load externally connected to the output terminal thereof, the current fed to the base of an output-stage transistor for driving the load to turn it on. In this circuit configuration, even if a base current of the output-stage transistor is so determined as to permit the semiconductor device to drive the heaviest permissible load, only a reduced amount of extra current is fed to the base of the output-stage transistor when it is turned on with a light load connected to the semiconductor device.
Claims8
A semiconductor device comprising:
- a constant-current source;
- a current amplifier circuit that is connected to an output side of the constant-current source;
- a first transistor that receives at a base thereof a current output from the current amplifier circuit, has an emitter thereof connected to a reference potential, and has a collector thereof connected to an output terminal;
- a second transistor that has a base thereof connected to the output terminal, has an emitter thereof connected to the output side of the constant-current source, and has a collector thereof connected to the reference potential, the second transistor being of an opposite conductivity type to the first transistor;
- and
- a third transistor that has a base thereof connected to the output side of the constant-current source, has an emitter thereof connected to the reference potential, and has a collector thereof connected to the output terminal,
- wherein the second transistor in conjunction with the third transistor operates so as to control the amount of current fed to the base of the first transistor by diverting and receiving part of a current directed to the current amplifier circuit before the current is fed thereinto.
A semiconductor device comprising:
- a current amplifier circuit that is connected to an output side of a constant-current source;
- a first transistor that has a base there of connected to an output side of the current amplifier circuit, has an emitter thereof connected to a reference potential, and has a collector thereof connected to an output terminal;
- a second transistor that has an emitter thereof connected to the output side of the constant-current source, has a collector thereof connected to the reference potential, and has a base thereof connected to the output terminal;
- and
- a third transistor that has a base thereof connected to an input side of the current amplifler circuit, has an emitter thereof connected to the reference potential, and has a collector thereof connected to the output terminal,
- wherein the second transistor operates so as to divert part of a current directed to the input side of the current amplifier circuit according to a voltage at the output terminal.
Dependencies are inferred from the claim text.