FR2588434A1 - OUTPUT CIRCUIT FOR ELECTRONIC ASSEMBLIES - Google Patents

Abstract

OUTPUT CIRCUIT FOR ELECTRONIC MOUNTINGS, ENSURING THE SWITCHING OF ELECTRIC RECEIVERS, WITH A PILOT CIRCUIT WHOSE OUTPUT IS CONNECTED TO THE ELECTRIC RECEIVER AND WITH A CONTROL CIRCUIT WITH TWO INPUTS FOR PULSE CONTROL OF THE PILOT CIRCUIT. THE OUTPUT OF THE NON-INVERTING PILOT CIRCUIT TR1 IS RETURNED TO ITS INPUT BY A REACTION RESISTOR R1, AND THE OUTPUT VOLTAGE OF THE AN1 CONTROL CIRCUIT IS CONTROLLED BY THE FIRST INPUT AND ITS OUTPUT RESISTANCE BY THE SECOND INPUT. THE OUTPUT CIRCUIT IS THUS PROTECTED AGAINST SHORT CIRCUITS AND OVERLOADS IN A SIMPLE AND ECONOMICAL WAY. ONLY REACTION RESISTANCE IS NECESSARY TO DO THIS.

Description

The present invention relates to an output circuit for

  electronic stages, in particular microcomputers, for the switching of electrical receivers, with a pilot circuit

  the output is connected to the electrical receiver and a com-

  two-input command for impulse attack of the pilot circuit. Electronic pilot circuit output circuits are frequently used for the control of electrical receivers of significant power, and in particular of incandescent lamps, relay coils or electric motors. Generally,

  the pilot circuits used, however, do not withstand

  circuits or overloads. A short circuit or overload can

  appear as a result of an error in the connection of the

  to the pilot circuit or in the case of a fault in the electrical receiver. The problem therefore arises of protecting the pilot circuit

  against short circuits and overloads.

  The patent application of the Federal Republic of Germany published under number 23 10 448 describes an output circuit with a

  circuit for the protection of an electronic switch. An in-

  electronic switch is used in this case as a pilot circuit.

  The control circuit is constituted by an AND operator, whose input receives the switching signal connecting the receiver and whose second input receives the same inverted switching signal and delayed by a semiconductor electronic component. In the case of a short circuit, the electronic switch is thus closed only during the short duration of a differential pulse and

  only when connecting the receiver. In the absence of short

  circuit at the output of the electronic switch, the potential applied to this output maintains the second input of the operator AND at a potential such that the electronic switch remains closed

  after the duration of the differential pulse.

  This known output circuit has the drawback of requiring

  many additional components to protect the driver circuit.

  the acquisition and assembly of components during manufacture are expensive and time consuming. Existing output circuits, and in particular circuits with a high degree of integration, can not always be equipped with the protection circuit,

  because the pilot circuit and the control circuit are not clearly

  separated. When the pilot circuit and the control circuit are arranged separately in space, their connection requires additional electrical conductors. The subsequent equipment,

  when possible, is an expensive operation.

  The invention aims to protect electronic circuits against

  short circuits and overloads in a simple and economical way.

nomic.

  According to an essential characteristic of the invention, the output of the non-inverting pilot circuit is brought back to its input by a

  reaction resistance; and the output voltage of the com-

  command is controlled by the first input and its output resistance

by the second entry.

  Its output is brought back to the entrance by a reaction resistance.

  The pilot circuit presents the properties of a flip-flop. The input of the pilot circuit is switched on or off by the control circuit, depending on whether a positive potential is applied or not by the electronic circuitry at the first input of the control circuit. As a result of the bistable property of the pilot circuit, its state in the high resistance phase of the circuit output

  control depends solely on the presence or absence of a short-

  circuit at the output of the pilot circuit. In the absence of a short circuit,

  the input of the pilot circuit is not influenced by its output.

  When a short-circuit or overload by a resistance receiver

  too low internal impedance appears at the output of the pilot circuit, this state is instantaneously transmitted to the input of the pilot circuit

which opens the receiver circuit.

  The output circuit according to the invention has in particular the advantage of a simple and economical constitution. Only one

  resistance is necessary. The pilot circuit and the circuit of

  are separated to a large extent, which allows the reaction.

  simple by the reaction resistance. The subsequent equipment of

  Existing output circuits is thus simple as well.

  According to another particularly advantageous characteristic

  of the invention, a clock, via the second

  trea, switches the output of the control circuit to low impulse resistance, in particular at a fixed frequency. The duration factor between the low and high resistance output states of the control circuit is chosen so that the control circuit is not overloaded in the event of a short circuit. Only a simple clock is necessary, which must not satisfy severe conditions of frequency stability and pulse duration. when

  short circuit or overload is removed during operation -

  of the output circuit according to the invention, the appearance of the pulse

  next clock plugs the electric receiver again.

  Other features and advantages of the invention will be

  better understood using the detailed description below

  of an exemplary embodiment, with a microcomputer and cir-

  cooked control and driver in the form of integrated circuits in

  a vehicle whose unique figure represents the diagram.

  In the figure, the positive terminal of a source B, made in the form of a starter battery of a vehicle, is connected

  at the first terminal of a switch S, realized in the form of

  ignition switch of the vehicle. The second terminal of the interrup-

  S is connected to the positive conductor + UB to which the potential

  positive end of the positive terminal of source B is applied when the

  switch S is closed. The latter is shown in the open position in the figure. The negative terminal of the source B is connected to the negative wire -UB, to which the negative supply voltage is thus applied. The negative wire -UB can also be connected to the vehicle ground by a ground wire. A microcomputer MC, an integrated control circuit AN and an integrated pilot circuit TR are each connected to the positive wire + UB and to the negative wire -UB, where appropriate via a divider or a voltage regulator. Several control circuits AN 1 to AN n are integrated in the control circuit AN. The constitution of the circuits of

  command AN 1 to AN n is identical. In other words, the cir-

  control dishes AN 1 to AN n are connected by power supply wires

  tation to the corresponding power supply wires of the

  built-in AN, inside the latter. Each of the control circuits AN 1 to AN n has two inputs, the first of which

  is directly connected to the corresponding outputs of the microcal-

  MC calculator by connections 1. The second inputs of the

  control circuits AN 1 to AN n are connected to each other

  the integrated control circuit AN, so that externally

  In the latter, they are connected by a common connection 2 to the clock T forming part of the microcomputer MC. The circuits

  AN 1 to AN n are each connected by second con-

  connections 3 to the corresponding pilot circuits TR 1 to TR n, which form part of the integrated pilot circuit TR. The pilot circuits TR 1 to TR n, forming part of the integrated pilot circuit TR, have an identical constitution. In other words, each driver circuit

  TR 1 to TR n is connected by power supply son to the son of

  corresponding circuits of the integrated pilot circuit TR. Each cir-

  baked pilot TR 1 to TR n has an output which is connected directly

  to the electrical receiver considered by third connections 4. In the figure, the output of the pilot circuit TR 1 is connected by

  example at the first terminal of a V incandescent lamp

  killing the electric receiver. The second terminal of the filament lamp is connected to the positive supply voltage of the positive wire + UB. The output of the pilot circuits TR 1 to TR n is

  reduced by reaction resistances R 1 to R n on the input of the -

  considered pilot circuit or output stage TR 1 to TR n.

  For the sake of clarity, only the control circuits AN 1

  and AN n as well as the pilot circuits TR 1 and TR n are represented

felt in the figure.

  The first connections 1 apply on the first entries

  control circuits AN 1 to AN n an electrical potential corre-

  corresponding to the state of the pilot circuits TR 1 to TR n controlled by the microcomputer MC. The potential on the first inputs of the control circuits AN 1 to AN n determines the output voltage of the control circuits AN 1 to AN n, which is transmitted by the

  second connections 3 to the inputs of the pilot circuits TR 1 to TR n.

  Through the common connection 2, the clock T, which is part of the microcomputer MC, delivers to the second inputs of the control circuits AN 1 to AN n an electrical potential which determines the resistance or the output impedance of the circuits. from command AN 1 to AN n. This clock alternately delivers a positive and negative potential or ground and has a fixed frequency. The ratio of the positive potential times and the negative potential times is chosen so that the T clock does not present

  virtually a high pulse potential. When a potential

  positive is applied to the first inputs of

  command AN 1 to AN n, the latter have a voltage output of

  positive tie. When a negative or ground potential is applied to the first inputs of the control circuits AN 1 to AN n, the latter have a negative output voltage or the ground potential. When a positive potential is applied to seconds

  inputs of the control circuits AN 1 to AN n, their outputs

  feel a weak resistance of exit. When a negative potential

  or mass is applied to the second inputs of the communication circuits.

  Means AN 1 to AN n, their outputs have an output resistor

  When a positive potential is applied to the inputs of the cir-

  TR 1 to TR n, the V receivers are switched off. When a negative or ground potential is applied to the inputs of the pilot circuits TR 1 to TR n, the receivers V are connected. The circuits

  drivers TR 1 to TR n switch without inversion. When receipts

  The receiver circuit is constituted by the source B, the switch S, the positive lead + UB, the receiver V, the pilot circuit TR 1 and the negative or ground lead -UB. When the

  receiver is connected, the pilot circuit TR 1 thus connects the first

  first terminal of the filament lamp at the power supply

  Negative sense of the negative or mass -UB wire. A positive potential on the first inputs of the control circuits AN 1 to AN n means that the receiver V is cut. A negative or ground potential on the first inputs of the control circuits AN i to AN n means that the receiver is connected. It is however also possible to invert the switching logic when the receiver V is switched with respect to the ground wire or negative -UB. It is for example possible to do this by inverting the switching logic in the microcomputer MC or to realize

  the control circuits with an inverting switching. The cir-

  pilot cookers connect the receivers for a positive input potential. The operation of the embodiment of the device according to the invention according to the single figure is as follows. All the control circuits AN 1 to AN n and all the pilot circuits TR 1 and TR n having the same constitution and the same connections,

  it suffices to describe the operation of the first com-

  in response to the first pilot circuit TR 1. When the ignition switch S is closed, the battery B supplies the microcomputer MC, the integrated control circuit AN and the integrated pilot circuit TR via the wire positive + UB and negative-wire or mass -UB. Positive lead + UB simultaneously applies the positive potential to the second terminal of the lamp

  incandescent V. The clock T is powered by the microcalcula-

  MC. The pilot control circuit AN feeds in particular the first control circuit AN 1. The integrated control circuit TR feeds in particular the first pilot circuit TR 1. When the positive potential is applied to the first input of the first control circuit AN 1, it is also applied to the output of the first control circuit AN 1 and therefore also to the input of the first driver circuit TR 1. The latter thus locks and the incandescent lamp V is cut off. This positive potential on the output of the first control circuit AN 1, however, acts on the input of the first pilot circuit TR 1 only when the clock T forming part of the microcomputer MC applies, through the common connection 2, the positive potential to the second input of the first control circuit AN 1. Then only, the output of the first

  control circuit AN 1 has a low resistance. This potential

  positive signal on the second input of the first control circuit AN 1, however, is applied only by pulses and is repeated at

  fixed frequency. When the negative or mass potential is applied

  that at the first input of the first control circuit AN 1, its output has a negative output voltage or the ground potential. This negative output voltage acts again only when the clock T applies the positive potential to the input of the first control circuit AN 1. When the positive potential is applied to the second input of the first control circuit AN 1, its output has low resistance. The negative potential

  the output of the first control circuit AN 1 is thus imposed

  at the input of the first driver circuit TR 1, which connects the first terminal of the filament lamp to the ground wire -UB, so that the receiver circuit is closed and the incandescent lamp V is connected. It is also possible for each occurrence of a potential variation on the first input of the control circuit AN 1, the timer T further switches the output on low resistance through the second input of the control circuit. AN 1, in order to avoid a delay of the connection and the cut-off of the receiver V. At the end of the short pulse phase of positive potential on the second input of the control circuit AN 1, the output of the latter has a high resistance . The output of the first control circuit AN 1 is thus decoupled from the input of the first pilot circuit TR 1. This latter, however, remains in its on state, so that the receiver circuit remains closed because the output of the first driver circuit TR 1 is brought back to

  its entry by the first reaction resistance R 1. The function

  This reaction is as follows. When the receiver circuit is closed and the receiver does not have an internal resistance too low, or the output of the first driver circuit TR 1 is not short-circuited, the voltage between the positive wire + UB and the negative or ground wire - UB falls almost entirely on the internal resistance of the receiver V. The negative or ground potential thus appears practically on the output of the first pilot circuit TR 1. The first reaction resistance R 1 imposes this negative or mass potential at 1 entry of the first pilot circuit

  TR 1. This is so as long as the output of the first com-

  Mande AN 1 is in its high resistance state. When the output of the first control circuit AN 1 is switched back to its low resistance state, the output voltage of the

  output of the first control circuit EN 1 again determines the

  state of the first pilot circuit TR 1. When the negative or ground potential remains applied to the first input of the first control circuit AN 1, the first pilot circuit TR 1 remains connected and consequently the receiver circuit remains closed. When, on the other hand, the positive potential is applied to the first input of the first control circuit AN 1, its output and consequently the input of the first pilot circuit TR 1 are brought to the positive potential. The first pilot circuit TR 1 interrupts the receiver circuit and the incandescent lamp V is cut off. When the first pilot circuit TR 1 is in the on state and consequently the receiver circuit containing the incandescent lamp V is closed, and when the input of the first pilot circuit TR 1 is decoupled from the output of the first control circuit AN 1 by a high resistance of the output di, the first control circuit AN 1, the voltage between the positive wire FUB and the negative or ground wire -UB drops essentially on the internal resistance of the first pilot circuit TR 1, in the

  in the event of a short circuit of the V incandescent lamp or a

  too low internal rate of the latter. In other words, the

  output of the first pilot circuit TR 1 has virtually the potential

  positive wire positive + UB. The entry and exit of the first

  pilot circuit TR 1 thus briefly present a different potential

  rent. The first reaction resistance R 1, however, imposes the

  output potential of the first pilot circuit TR 1 at its input.

  The input and the output of the first pilot circuit TR 1 thus again have the same potential, positive in this case. The potential

  positive on the input of the first pilot circuit TR 1 causes the in-

  by the latter of the receiver circuit containing the incandescent lamp V. When the output of the first control circuit AN 1 briefly showed a low output resistance, as a result of a positive voltage pulse applied to its second input by the T clock, the output of the first control circuit AN 1 and the input of the first driver circuit TR 1 are

  again coupled during the short duration of the pulse of

  positively. When the negative potential is then applied to

  the output of the first control circuit AN 1 and consequently the

  TR 1, the latter is, even in case of short circuit or overload, brought into the on state during the short duration of the positive voltage pulse and therefore the

  Receiver crcuit containing the incandescent lamp V is closed.

  The duration of the short positive voltage pulse delivered by the clock T is, however, chosen to be sufficiently small so that, in the event of a short-circuit, the first pilot circuit TR 1 is not overloaded by the generation of heat during the voltage drop in the receiver circuit, across the internal resistor of the first pilot circuit TR 1. The admissible duration of the positive voltage pulse of the clock T is essentially determined by the internal resistance of the switching circuit of the pilot circuit.

  TR 1 in the receiver circuit and the thermal capacity of the

  said switching circuit. At the end of the duration of the voltage pulse of the clock T, repeating itself periodically at a fixed frequency, the output of the first control circuit AN 1 again has a high resistance and consequently the input of the first pilot circuit TR 1 is again decoupled from the output of the first control circuit AN 1. When the short circuit or the overload is removed in the receiver circuit, after for example the replacement of the defective or incorrect receiver by a receiver having the electrical characteristics correct, the first pilot circuit TR 1 is brought into the on state and the receiver circuit is subsequently closed again when the negative or ground potential remains applied to the output of the first control circuit AN 1, and as soon as the positive voltage pulse of the clock T switches briefly again. Its output in the low resistance state,

the end of the period.

  The device of the embodiment according to FIG.

  In particular, the unique advantage is that when

  electronic mutation of several electrical receivers in

  several different receiver circuits in the case of a short

2588434-

  circuit or an overload in one of these circuits, the electronic assembly makes it possible to continue to control the other circuits

  receiver via the output circuit according to the invention.

  tion. Elimination of short circuit or overload by replacing

  placement of defective receivers or receivers with too low internal resistance by internal resistance receivers

  sufficiently high can be achieved while the electro-

  and the output circuits are in use, so that eventual

  time-critical operations, during which recep-

  electric motors are switched, are not disturbed by a short-

  circuit or overload in another receiver circuit and its removal. A time-critical operation is for example the control of the ignition and / or injection of gasoline into a vehicle engine, which also depends on the angle of calibration

  cranks of the internal combustion engine running. This com

  control or regulation of ignitions or fuel injections can be carried out by the electronic assembly of the microcomputer MC in

  the embodiment according to the single figure.

  The constitution of the output circuit according to the invention is particularly simple when the control circuits and / or the

  Pilot circuits already exist for the many exits required

  such as in large electronic assemblies such as computer sys-

  central microprocessor systems. In the latter, the clock T for example must be made as part of the microcomputer MC, by adding appropriate blocks to the computer program. When

  the pilot circuits are already united in an inte-

  TR suit, it is sufficient to establish the connections between the latter and the printed circuit board of the rest of the electronic circuit to provide a

  intermediate piece, in the form of a base in which are in-

  the reaction resistances R required according to the invention.

  In this case, a modification of the layout of the printed circuit is unnecessary for the subsequent equipment of the output circuit according to the invention. The subsequent equipment for electronic assemblies with the output circuit according to the invention is thus particularly

simple and economical.

- the.

  The output circuits according to the invention are particularly suitable

  very well for use in vehicles, because the electrical assemblies

  tronic are particularly sensitive due to particular mounting conditions, such as vibrations in the vehicle, and environmental influences. It is the same for electrical receivers, such as incandescent lamps whose filaments, for example, may become detached from the hooks under the effect of vibrations and easily cause short circuits.

  in the base, on the crossing of the hooks.

  It is also possible to use as the control circuit AN a shift register in which the microprocessor MC serially transfers the information corresponding to the states of the pilot circuits TR 1 to TR n. The shift register then also has a second input 2 whose input potential determines the resistance

outputs of said register.

  Of course, various modifications may be made by those skilled in the art to the principle and to the devices which have just been described solely by way of nonlimiting examples, without

depart from the scope of the invention.

Claims (9)

claims   1. Output circuit for electronic assemblies, microcalcula-   in particular, for the switching of electrical receivers,   with a pilot circuit whose output is connected to the electrical receiver   a control circuit with two inputs for the impulse driving of the pilot circuit, said output circuit being characterized in that the output of the non-inverting pilot circuit (TR 1) is returned to its input by a feedback resistor ( R 1); and the output voltage of the control circuit (AN 1) is controlled by the first input and its output resistance by the second input. 2. Output circuit according to claim 1, characterized in that   that a clock (T), via the second input,   mute the output of the control circuit (AN 1) on low resistance by   pulses, in particular at a fixed frequency.   3. Output circuit according to claim 1, characterized in that a clock (T), at each potential inversion on the first input of the control circuit (AN 1), pulses the   output of the control circuit (AN 1) on low resistance, by the in- intermediate of the second entry.   4. Output circuit according to claim 1, characterized in that the pilot circuit (TR 1) is embodied as an integrated circuit, and in particular as a part of a circuit Integrated driver (TR).   5. Output circuit according to claim 1, characterized in that the control circuit (AN 1) is embodied as an integrated circuit, and in particular as a part of a control circuit. integrated control (AN).   Output circuit according to claim 2, characterized in that   that the clock (T) is formed as a part of a micro- calculator (MC).   7. Output circuit according to claim 4, characterized in that the integrated pilot circuit (TR) is connected by a base to the rest of the circuit; and the reaction resistors (R 1 to R n) are part of of the base.   Output circuit according to claim 5, characterized in that   that the integrated control circuit (AN) has a number of   I inputs and outputs equal to that of the control circuits (AN 1 to AN n) combined in the integrated control circuit (AN); and the integrated control circuit (AN) has only one second   input for the common switching on low resistance of   control circuits (AN 1 to AN n).   9. Use of the output circuit according to claim 1, in a vehicle.