SU1129725A1 - Device for shaping unblocking pulse - Google Patents

Abstract

A DEVICE FORMATION OF A SETUP PULSE, containing an inverter and an RC circuit, one capacitor plate of which is connected to. one power supply bus, another with an inverter input and an RC circuit resistor with another power supply bus, characterized in that, in order to expand the functional capabilities of the device by forming a setting pulse at any speed and power supply voltage dips, It has a threshold electronic key inserted between the power supply buses, whose input is connected to the second power supply bus, and the output is connected to the input of the inverter. j to OC SP

Description

1 The invention relates to automation and computing technology and is intended to set the trigger circuits to their original state immediately upon switching on the supply voltage. A device for setting the trigger circuits to an initial state, comprising a bridge circuit, a comparator and a pulse shaper, the inputs of the comparator are connected to the diagonal of the bridge formed by the active divider and the integrating RC chain, the supply voltage is applied to the second diagonal of the bridge, the output of the comparator is connected with the input of the pulse former flj. A disadvantage of this device is the relative low reliability of operation, since the comparator must monitor the potential difference in the diagonal of the bridge and generate a setting impulse while the supply voltage of the comparator itself rises and at its output can be an arbitrary signal. In addition, reliable operation of the device largely depends on the parameters of the RC circuit, because, at the rate of increase of the supply voltage, comparable to the RC time constant, the output pulse will not form a setting pulse. To eliminate this deficiency, it is necessary to increase the RC-c pi time constant, but at the same time the device becomes insensitive to power voltage dips below the established standard, which leads to a decrease in the reliability of its operation. The closest technical solution to the invention is a device for forming an installation pulse, containing the first and second elements OR NOT, the outputs of which are connected to the first inputs of the second and first elements ORINE, and the first and second RC chains, the capacitors of which are connected to the common bus and via resistors of RC chains with a common point, and the second input of the first element OR is NOT connected to the connection of a capacitor and a resistor of the first RC chain, the common point of the resistor of the RC chains is connected to the power bus, and Ineni second capacitor and a resistor RC-ki tsepoch5 linked via an inverter to the second input of the second OR-NO element 23. The drawback of this device is the dependence of the work from the EU-circuit parameters. In the case of a low rate of increase in the supply voltage, to ensure the formation of a setup signal, it is necessary to increase the RC time constant, which reduces the likelihood of generating the required setup signal during supply voltage dips, the duration of which can be arbitrary, since the capacitor cannot to zero to the time of failure, and the formation of a pulse occurs at the moment of charge to the threshold of the operation of the UTI-NOT element. The purpose of the invention is to expand the functionality of the device Realizations by forming an adjusting impulse at any rate of rise and power supply voltage dips. The goal is achieved by the fact that a setup pulse shaping device containing an inverter and an RC circuit, one capacitor plate of which is connected to one power supply bus, the other to the inverter input and through a C circuit resistor to another power supply bus, A threshold electronic key, connected between the bus: the power supply, whose input is connected to the second power supply bus, and the output is connected to the input of the inverter. FIG. 1 shows a diagram of a device for forming a setting pulse; in fig. 2 - scheme of the electronic threshold key; in fig. 3D diagram of the device. The installation pulse shaping device comprises an inverter 1 connected at the output of the RC circuit 2, comprising a resistor 3 and a capacitor 4, an output 5 of the device, power supply bus 6.7, an electronic threshold switch 8 connected between the power supply buses in parallel to the RC- chains. Electronic threshold key 8 contains a divider resistors 9,10, Zener diode 11, resistors 12, 13 and transistors 14,15. The device works as follows. When the supply voltage is applied (Fig. 3a) to the tires 6.7 until then.

as long as its value is lower than the predetermined threshold value of the electronic threshold switch 8, the switch 8 shunts the capacitor 4 of the RC circuit 2 (the voltage on the capacitor 4 is equal to zero in Fig. 3B), while the output voltage of the inverter 1 may be unspecified (dotted line diagram of Fig. Sv). The threshold of the electronic key 8 is chosen equal to the value close to the minimum allowable value of the supply voltage of the trigger circuits. As long as the supply voltage is less than the electronic key operating threshold, the TOK through the Zener diode 11 and the base of the transistor t4 does not flow, the transistor 14 is in the locked state, the transistor 15 is open. When the value of the supply voltage reaches the threshold of operation of the key 8, as a result of which the transistor 14 of the key opens, and the transistor 15 closes, the shunt stops; the action of the switch 8 on the capacitor 4 of the RC circuit 2 and the charging of the capacitor 4 begins. At this moment, the output of the inverter 1 is set to the voltage level of the logical unit. When the voltage on the capacitor reaches a value that the inverter perceives as a logical unit,

the output of inverter 1 is set to | with a logic level zero. The voltage pulse of the logical unit from the output of the inverter 1 is used to set the trigger circuits to their initial state. As can be seen, the formation of the installation pulse starts at the moment when the supply voltage reaches a certain value, regardless of its rate of rise. This value is determined by the threshold of operation of the electronic key 8 and is chosen close to the value minimally acceptable for the power-triggering circuits.

When the power voltage fails below the set threshold of the electronic switch 8, the current through the Zener diode 11 is closed, the transistor 14 is closed and the transistor 15 is opened, through which the capacitor 4 is quickly discharged. The voltage goes below the minimum acceptable value the output signal of the inverter 1 may have an indefinite level (shown in the diagram by the dotted line in Fig. Next, when the supply voltage rises after the failure, the device operates in the same way as power on.

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Claims (1)

DEVICE FORMING THE INSTALLATION PULSE, containing an inverter and an RC circuit, one capacitor plate of which is connected to one power supply bus, the other to the inverter input and through the RC circuit resistor to another power supply bus, characterized in that, with the purpose of expanding the functionality of the device by forming a set pulse at any slew rate and voltage dips ”of the power supply, a threshold electronic key is inserted into it, included between the buses of the power supply, the input of which о is connected to the second bus of the power source, and the output is connected to the input of the inverter. q> f Figure 1