Control apparatus with reduced quiescent current

Details Control apparatus with reduced quiescent current Control apparatus with reduced quiescent current

1999-06-18

2000-04-11

Riley, Shawn

Electricity: power supply or regulation systems

Output level responsive

Using a three or more terminal semiconductive device as the...

323288, 323289, G05F 140

Patent

active

06049199&

DESCRIPTION:

BRIEF SUMMARY
FIELD OF THE INVENTION

The present invention relates to a controller with a final stage which provides a defined supply voltage for a downstream electronic circuit and a circuit stage upstream from the final stage for the reduction of the quiescent current supplied by a voltage source.


BACKGROUND INFORMATION

In controllers which are supplied on a continuous basis with battery voltage, a quiescent current draw of 100 .mu.A to 500 .mu.A is required. The lower value in particular cannot be achieved with conventional voltage regulators.


SUMMARY OF THE INVENTION

The object of the present invention is to make available a controller of the above type with which a reduction of the quiescent current well below conventional values can be achieved.
Thus, it is provided that the circuit stage has an electronic switch that can be set to the open or the closed condition by a target-value signal provided by the controller circuit. Because the electronic switch, which is situated upstream from the final stage that provides the supply voltage for the downstream electronic circuit, can be set to the open condition, the quiescent current can be reduced in the inactive condition of the electronic circuit to values that are significantly below 100 .mu.A. To activate the electronic circuit, the switch is set to the closed condition.
A simple method of control is provided in that the target value signal is a pulse-wide modulated digital signal.
In a simple design of the controller for reducing the quiescent current, the switch is a transistor whose emitter is connected to the positive pole of the voltage source and whose collector is connected to the final stage. A capacitor and a diode are connected in series between an output of the controlled circuit that provides the target signal and the emitter, the cathode of the diode being connected to the terminal of the controller circuit and the anode connected to a terminal of the capacitor, the other terminal of which is connected to the emitter. The base of the transistor is connected via a resistor between the diode and the capacitor. For achieving a defined condition, according to one embodiment of the present invention, an additional resistor is connected parallel to the series connection of capacitor and diode.
If the time constants formed by the capacitor and the resistor and the pulse duration are large enough that the switch in the form of the transistor remains in the closed condition during the pulse duration in the active condition of the electronic circuit, it is assured by simple means that in the active condition of the downstream electronic circuit it is supplied with the defined supply voltage from the final stage.
In an alternative embodiment, the target-value signal can also be defined as an analog signal. The capacitor and the diode can then be omitted and the resistor is connected with its terminal that is distant from the base to the terminal for the target-value signal.


BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a schematic circuit arrangement of the controller according to one embodiment of the present invention.
FIG. 2 shows signal curves of voltage at points A and B according to FIG. 1 according to one embodiment of the present invention.


DETAILED DESCRIPTION

In FIG. 1, the circuit arrangement of a controller is schematically presented. A voltage regulator SR provides supply voltage VCC for a downstream electronic circuit, such as for example a microcontroller or microprocessor. Between a voltage source, which provides battery voltage Ubat, and voltage regulator SR, a circuit stage ST is connected with which the quiescent current of voltage regulator SR is minimized in the non-active condition of the electronic circuit.
Circuit stage ST has as an electronic switch a transistor T, the emitter of which is connected to the positive pole of the voltage source and the collector of which is connected to voltage regulator SR. Furthermore, circuit stage ST is connected on the input side, by way of example, to a terminal of an external control circu

REFERENCES:
patent: 4061931 (1977-12-01), Boschert
patent: 4692688 (1987-09-01), Stanojevic
patent: 4885522 (1989-12-01), Konopka
patent: 5220272 (1993-06-01), Nelson
patent: 5414340 (1995-05-01), Gannon
patent: 5523940 (1996-06-01), Wymelenberg
patent: 5532914 (1996-07-01), Kageyama

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