DD156756B1

DD156756B1 - UNIVERSAL TRIGGERELEMENT

Info

Publication number: DD156756B1
Application number: DD22810781A
Authority: DD
Inventors: Horst Wolf
Original assignee: Horst Wolf
Priority date: 1981-03-06
Filing date: 1981-03-06
Publication date: 1986-02-05
Also published as: DD156756A1

Description

-2- 228 107 4-2- 228 107 4

Ausführungsbeispielembodiment

Die Erfindung soll nachstehend an einem Ausführungsbeispiel näher erläutert werden.The invention will be explained in more detail below using an exemplary embodiment.

Die dazugehörige Zeichnung zeigt das Triggerelement, bestehend aus den drei Halbleiterelementen V1 bis V3, und den Widerständen R1 bis R2 im Zusammenwirken mit einer Regelschaltung μΑ 723 als Überstromschutzschaltung bei einer Stromversorgungsschaltung. Auf den zweiten Eingang des Triggerelements wird die Ausgangsspannung rückgekoppelt. An dem Strommeßwiderstand Rs wird ein dem zu überwachenden Strom proportionaler Spannungsabfall erzeugt und dem Triggerelement als Signalspannung zugeführt. Ist der Ansprechwert erreicht, wird das Halbleiterelement V3 leitend und sperrt den Schaltkreis μΑ 723 soweit, bis der zu überwachende Strom nicht mehr ansteigt.The accompanying drawing shows the trigger element, consisting of the three semiconductor elements V1 to V3, and the resistors R1 to R2 in cooperation with a control circuit μΑ 723 as overcurrent protection circuit in a power supply circuit. On the second input of the trigger element, the output voltage is fed back. At the current measuring resistor Rs a voltage drop proportional to the current to be monitored is generated and supplied to the trigger element as a signal voltage. If the response value is reached, the semiconductor element V3 becomes conductive and blocks the circuit μΑ 723 until the current to be monitored no longer rises.

Die geregelte Ausgangsspannung sinkt — bei Kurzschluß bis auf Null — und verringert über die Rückkopplung den Ansprechwert, so daß nun ein wesentlich geringerer Spannungsabfall an dem Strommeßwiderstand Rs ausreicht — kleinerer Strom durch den Strommeßwiderstand Rs—um das Halbleiterelement V3 im leitenden Zustand zu halten. Der Ansprechwert ist identisch mit dem Spannungsabfall an R1: = Uri, vermindert um den Spannungsabfall an R2: = Ur₂ - U_R1 und Ur₂ werden aus der Referenzspannungsquelle des Regelschaltkreises μΑ 723 durch Spannungsteilung vorgegeben. Im Anfangszustand ist das Halbleiterelement V2 durch den aus der Referenzspannungsquelleeingespeisten Strom leitend und das Halbleiterelement V1 ist gesperrt. Mit wachsender Signalspannung muß ein steigender Anteil des eingespeisten Stromes über das Halbleiterelement V1 und den Widerstand R1 fließen, denn die Polarität der Signalspannung liegt so, daß das Halbleiterelement V2 wegen wachsendem Emitterpotential zugesteuert wird. Erreicht die Signalspannung den Ansprechwert, steigt die Kollektorspannung des Halbleiterelements V2 bis auf die Öffnungsspannung des Halbleiterelements V 3. Diese entspricht der vom Spannungsteiler abgegriffenen Referenzspannung, da wegen der Regelwirkung und der hohen Verstärkung des Regelschaftkreises μΑ 723 U_e+ = Ue- wird.The regulated output voltage drops - when shorted to zero - and reduces the response via the feedback, so that now a much lower voltage drop across the current measuring resistor Rs is sufficient - smaller current through the current measuring resistor Rs-to keep the semiconductor element V3 in the on state. The response value is identical to the voltage drop at R1: = Uri, reduced by the voltage drop across R2: = Ur ₂ - U _R1 and Ur ₂ are specified from the reference voltage source of the control circuit μΑ 723 by voltage division. In the initial state, the semiconductor element V2 is conductive by the current fed from the reference voltage source and the semiconductor element V1 is blocked. With increasing signal voltage, an increasing proportion of the injected current must flow through the semiconductor element V1 and the resistor R1, because the polarity of the signal voltage is such that the semiconductor element V2 is controlled due to increasing emitter potential. If the signal voltage reaches the threshold value, the collector voltage of the semiconductor element V2 rises to the opening voltage of the semiconductor element V 3. This corresponds to the tapped by the voltage divider reference voltage, since because of the control effect and the high gain of the control circuit μΑ 723 U _{e +} = Ue- is.

Ansprechwert = U^₁ - U_R? mit U^₁ = ^j (U_q+ - ^_ΉΤΓΤΓ^) und U_QO = -^r (U_„^ - U,Pickup value = U ^ ₁ - U _R? with U ^ ₁ = ^ j (U _{q +} - ^ _ΉΤΓΤΓ ^) and U _QO = - ^ r (U _ "^ - U,

Wird die Ausgangsspannung überlastet, führt ihr Absinken zu einem niederen Emitterpotential des Halbleiterelements V3 (undIf the output voltage is overloaded, its sinking leads to a lower emitter potential of the semiconductor element V3 (and

Um das Halbleiterelement V3 zu sperren, muß das Kollektorpotential des Halbleiterelements V2 um den selben Betrag sinken. Das ruft einen größeren Spannungsabfall an dem Widerstand R 2 hervor, wodurch sich der Ansprechwert verringert. Im Extremfall bei Ua = 0 gilt:In order to block the semiconductor element V3, the collector potential of the semiconductor element V2 must decrease by the same amount. This causes a larger voltage drop across the resistor R 2, which reduces the threshold. In the extreme case at Ua = 0, the following applies:

^UR2 ⁼ Rl ^(Uref "* ^U R2 ⁼ Rl ^(U ref "*

Der Haltewert des Triggers, auf diese Weise von der sich ändernden geregelten Ausgangsspannung Ua gesteuert, wird durch die Wahl eines Widerstandsverhältnisses in seinem Funktionsbereich vorgegeben.The hold value of the trigger, controlled in this way by the changing regulated output voltage Ua, is predetermined by the selection of a resistance ratio in its operating range.

Haltewert = Ansprechwert durch R 2 = 0Holding value = pickup value by R 2 = 0

Haltewert < Ansprechwert durch Ur2 < UriHold value <threshold value by Ur2 <Uri

Haltewert = 0 durch U_R2 = Ur₁ Holding value = 0 through U _R2 = Ur ₁

Haltewert < 0 durch Ur₂ > UriHold <0 by Ur ₂ > Uri

Die beiden letzten Fälle bedeuten, daß der Trigger nach dem Ansprechen nur durch äußeren Eingriff oder eine Signalspannung entgegengesetzter Polarität in seinen Ausgangszustand zurückgeschaltet werden kann. Das entspricht der Charakteristik eines Flip-Flop.The last two cases mean that the trigger can be switched back to its initial state after the response only by external intervention or a signal voltage of opposite polarity. This corresponds to the characteristic of a flip-flop.

Claims

-1- 228 107 4

Invention claim:

Universal trigger element comprising two controllable semiconductor elements, characterized in that their control electrodes and the first main electrode of a semiconductor element (V1) are connected to a current source and the second main electrode of the same semiconductor element (V1) in series with a resistor (R1) and the main electrode of another semiconductor element (V2) represent the input of the universal trigger element, while the first main electrode of the second semiconductor element (V2) is the output, that the second main electrode of the second semiconductor element (V2), a resistor (R2) in series, that the first main electrode of the second semiconductor element (V2) is connected to a current source and the control electrode of another semiconductor element (V3) and the first main electrode of the third semiconductor element (V3) is a negated output, while the second main electrode is the second control input of the universal trigger element.

For this 1 page drawing

Field of application of the invention t,

The invention can be used as an independent trigger circuit and includes control, regulation, protection and monitoring circuits for the electrical variables current and voltage.

Characteristic of the known technical solutions

Known trigger circuits use the non-linear input characteristics of semiconductors (Si transistors, FETs, Zener diodes, light-emitting diodes). The summation of the threshold value of a transistor with a predetermined ohmic voltage drop makes the Schmitt trigger to a basic circuit. A disadvantage is the direct dependence of the response value of the scattering of said input characteristics and their temperature response in these types of circuits. These disadvantages can be eliminated with compensated operational amplifiers or comparators. One also gains the advantage of a very small response voltage. However, the additional operating voltage of opposite polarity proves to be expensive if the response value has to be measured to zero (eg current limitation in the case of a short circuit).

Object of the invention

The aim of the invention is to provide an integration-friendly universal trigger element that can be used directly in or with integrated control and regulating circuits and has the known advantages of a very low, temperature and copy-independent response value.

Explanation of the essence of the invention

The invention has for its object to provide a trigger circuit that does not require additional operating voltage of opposite polarity and has an arbitrarily folded back hold value. According to the invention the object is achieved in that the input characteristic of a controllable semiconductor element with a second semiconductor element of the same type is compensated. To achieve this, the control electrodes of the two semiconductor elements are connected in parallel and driven by a constant current. While the one main electrode of the first semiconductor element is connected to the parallel-connected control inputs, the other main electrode thereof forms in series with a first resistor an input terminal of the universal trigger element. The other input terminal is formed by a main electrode of the second semiconductor element. The other main electrode of the second semiconductor element receives the working potential.

In the static operating state without signal voltage, the second semiconductor element is controlled and between the two main electrodes is - except a residual voltage - no potential. A signal voltage between the two input terminals must be so large until it compensates for the voltage drop across the first resistor (unstable equilibrium) and exceeds. It has the effect that the second semiconductor element is controlled in accordance with its characteristic and the working potential is present across its two main electrodes. When the signal voltage drops, the switching is almost hysteresis-free.

The passage and control of the second semiconductor element can be made dependent on the height of the working potential by inserting a resistor into the input-side main electrode of the second semiconductor element. The working current through the second semiconductor element causes a voltage drop across the second resistor, and this counteracts the signal voltage, thus has an influence on the breakpoint of the trigger element after switching over when driving through and controlling the second semiconductor element via the operating current changing. To the working potential of the second semiconductor element can be connected to the control electrode, a third semiconductor element whose one main electrode also receives a working potential and the other main electrode is a second input of the trigger element. With a potential at this input, the breakpoint can be controlled continuously or programmed by specifying fixed potentials. The working potential of the third semiconductor element reacts negated to the working potential of the second semiconductor element.