Electronic digital logic circuitry – Interface – Current driving
Reexamination Certificate
1999-10-04
2001-03-20
Tokar, Michael (Department: 2819)
Electronic digital logic circuitry
Interface
Current driving
C123S644000
Reexamination Certificate
active
06204693
ABSTRACT:
BACKGROUND OF THE INVENTION
Field of the Invention
The invention relates to an apparatus for regulating the flow of current through a load which is connected to ground via a measurement line. A current is output onto an output line by a device connected to the measurement line which depends on the measured voltage on the measurement line. In a more specific embodiment, the invention relates to an apparatus for regulating the flow of current through a load connected between a positive potential and a first measurement resistor which is connected to ground via a measurement line. A current is output on an output line in dependence on a voltage measured on the measurement line and the output line is connected to a predetermined potential via a second measurement resistor.
German patent DE39 08 558 discloses a signal transmission system in which an analog signal and a digital signal are transmitted to a receiver from a transmitter via a data line. In the receiver, the analog signal and the digital signal are evaluated independently of one another.
German published patent application DE38 26 663 A1 discloses a method and a circuit for simultaneously transmitting operational data, in which operational data and voice signals are transmitted via a line. In that context, the peak values of the operational data are chosen to be higher than the maximum peak values of the voice signals so that the signals can be mixed and the operational data can be recovered from the voice signal using a comparison voltage at the reception location. The voice signal is obtained by subtracting the selected operational data from the mixed signal.
German published patent application DE195 11 140 A1 discloses an apparatus for serial data interchange between two stations via a common data transmission line. The first station recognizes the different bit states on the data line by their different voltage levels. The second station recognizes the different bit states on the data transmission line by the presence or absence of a particular flow of current. The voltage levels are evaluated differently by the stations, so that data can be transmitted in both directions at the same time.
German published patent application DE40 05 813 A1 describes an apparatus for regulating the flow of current through a load. The load is connected in series with a transistor and a measurement resistor. The voltage drop which the load current causes across the measurement resistor is compared with a reference voltage using an operational amplifier. If the voltage drop across the measurement resistor is more than a predetermined value, then an output signal is output which is used to control the load current.
SUMMARY OF THE INVENTION
It is accordingly an object of the invention to provide a device for regulating the current flow through a consumer, which overcomes the above-mentioned disadvantages of the heretofore-known devices and methods of this general type and which is of simple design and enables precise and simple regulation of the flow of current.
With the foregoing and other objects in view there is provided, in accordance with the invention, an apparatus for regulating a flow of current through a load, comprising:
a measurement line connecting a load to ground;
a current source connected to the measurement line and to an output line, the current source outputting a current onto the output line in dependence on a voltage on the measurement line; an arithmetic and logic unit having an analog input and a digital input each connected to the output line;
a switch connected to the arithmetic and logic unit;
the arithmetic and logic unit determining a value of the voltage on the output line via the analog input and, depending on the voltage determined via the analog input, regulating the flow of current through the load via the switch;
the arithmetic and logic unit determining the voltage on the output line via the digital input and deciding whether there is a low signal; and
the arithmetic and logic unit, if there is a low signal at the digital input, opening the switch in a predeterminable time range and thereby interrupting the flow of current through the load.
With the above objects in view there is also provided, in accordance with the invention, an apparatus for regulating a flow of current through a load connected between a positive potential and a first measurement resistor connected to ground via a measurement line, comprising:
a first current source connected to a measurement line and to an output line connected to a predetermined potential via a second measurement resistor, the current source outputting a first current onto the output line in dependence on a voltage on the measurement line;
a second current source connected to the measurement line and to the output line, the second current source outputting a second current onto the output line if the voltage on the measurement line is lower than a predetermined limit value, the second current having a value causing a voltage on the output line to fall below a predetermined value;
an arithmetic and logic unit having an analog input and a digital input each connected to the output line;
a second switch connected to the arithmetic and logic unit and inserted between the load and the measurement line;
the arithmetic and logic unit determining a value of the voltage on the output line via the analog input, and controlling the second switch in dependence on the voltage determined via the analog input and thereby regulating a flow of current through the load;
the arithmetic and logic unit determining the voltage on the output line via the digital input to decide whether there is a low signal; and
if there is a low signal at the digital input, the arithmetic and logic unit opening the second switch in a predeterminable time range and thereby interrupting the flow of current through the load.
In accordance with an added feature of the invention, the (first) current source is a voltage-dependent current source.
In accordance with an additional feature of the invention, the second current source comprises an operational amplifier having a first input connected to the measurement line, a second input connected to a constant voltage source, and an output, a first switch connected to the output of the operational amplifier and between the output line and ground, the operational amplifier comparing the voltage on the measurement line with a reference voltage of the constant voltage source and opening the first switch if the voltage on the measurement line is lower than the reference voltage, and closing the first switch if the voltage on the measurement line is higher than the reference voltage.
In accordance with a concomitant feature of the invention, the load is an ignition coil protected against overcurrent by the arithmetic and logic unit.
Other features which are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in an apparatus for regulating the flow of current through a load, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.
REFERENCES:
patent: 5043633 (1991-08-01), Perkins
patent: 5775310 (1998-07-01), Ito et al.
patent: 5970964 (1999-10-01), Furuhata et al.
patent: 6100728 (2000-08-01), Shreve et al.
patent: 3826663A1 (1990-02-01), None
patent: 3908558C2 (1990-12-01), None
patent: 4005813A1 (1991-08-01), None
patent: 4231954A1 (1994-03-01), None
patent: 195 11 140A1 (1996-10-01), None
patent: 0281528A1 (1988-09-01), None
patent: 0428315A2 (1991-05-01), None
patent: 05079436A (1993-03-01), None
patent: 08028415A (19
Fisch Alfons
Forster Ralf
Greenberg Laurence A.
Le Don Phu
Lerner Herbert L.
Siemens Aktiengesellschaft
Stemer Werner H.
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