SU866711A1 - Trigger device - Google Patents

Description

I

The invention relates to a pulse technique, in particular to noise-resistant asynchronous triggers, and can be used as a memory element in automation systems.

A trigger is known that contains an NAND element in each arm, the output of each of which is connected to the input of another p.

The disadvantage of this device is low noise immunity, i.e. the trigger can be switched when an interference signal appears on its inputs.

The closest in technical essence to the proposed is. a device containing a main and two auxiliary triggers made on the Schaeffer elements and RC filters included in each of the cross-links of the main trigger 2.

The disadvantages of the known device are low noise immunity and low reliability due to the large

load logic elements rc filters.

The purpose of the invention is to improve the noise immunity and reliability of the device.

To achieve this goal in a trigger device containing two elements AND-NOT and two RC filters, the outputs of the first and second elements AND-NOT are connected respectively to the first inputs of the second and first elements AND-NOT, the second inputs of which are connected to the inputs of the device, the outputs the first and second elements of the NAND through an IS, diodes and resistors connected in series, are connected respectively to the third inputs of the second and first elements of the NAND and the first plates of the capacitors, the second plates

which are connected to a common bus.

Claims (2)

The drawing shows a schematic diagram of a trigger device. The trigger device contains two elements IS-NOT and 2, two RC filters 3 and 4, including resistors 5 and 6 and capacitors 7 and 8, and diodes 9 and 10, and the output of the element AND-HE I is connected to the output 11 of the trigger and the first input element AND-NOT 2, and the output of the element AND-NOT 2 - with the output of the 12 trigger device and the first input of the element AND-NOT 1, the second inputs of the elements; AND-NOT 1 and 2 are connected to the inputs 13 and 14 of the trigger device, the resistor 5 connected to the anode 9M of the diode 9, the cathode of the diode 9 to the output of the element AND NOT 2, the connection point of the resistor 5 and the capacitor 7 is connected to the third in the element is NOT-1, and the capacitor is the 1st common busbar 15, the resistor 6 is connected to the diode 10 diode, the cathode of the diode 10 is connected to the output of the AND-NE element 1, the connection point of the resistor 6 and the capacitor 8 is connected to the third input of the element AND-NOT 2, and the capacitor 8 - with a common bus 15. The trigger device operates as follows. Let at the output of the element AND-NOT 1 be logical O, then at the output of the element AND-NOT 2 logical 1. Krndensator 8 is discharged. When a trigger device of logical O appears at input 13, at the third input of the NANDI element 2, the voltage rises n exponentially, and the voltage rise rate is determined by the capacitance of the capacitor 8 and the input resistance of the NAND element 2. Upon reaching at the third input of the NE-2 element of a voltage sufficient to trigger this element, the logical O is set at the output of the IS-NOT 2 element. The trigger device changes its state. If the duration of the logic signal at the input of the trigger device is less than the time for the voltage rising at the third input of the AND-NOT 2 element to a value sufficient for 14 liters of the switching element of the AND-NOT 2, then the rigger device does not change its cooling. The discharge current of the capacitor 8 is determined by the resistance of the resistor 6, which can be chosen such that the current of the output transistor of the element. AND-NO 1 did not exceed the permissible values. At the same time, static noise immunity is not reduced, since there are no elements in the input circuit of the NAND 2 element. The proposed device is expedient to use at the outputs of unprotected communication lines, while it is possible to increase the stability level by increasing the capacitances of the capacitors of the RC filters without increasing the load on the logic elements, thus increasing the reliability of operation. A trigger device comprising two NAND elements and two RC filters, the outputs of the first and second elements NAND are connected respectively to the first inputs of the second and first elements NAND, the second inputs of which are connected to the inputs of the device, characterized in that In order to improve noise immunity, the outputs of the first and second elements of NAND are connected via successively connected diodes and resistors respectively to the third inputs of the second and first elements of NAND and the first capacitor plates, the second plates to oryh podklyucheshl to a common bus. Sources of information taken into account in the examination 1.Bukreev I.N., Mansurov B.M., Gorchev V.I. Mik1) electronic circuits of digital devices. M., Soviet Radio, 1975, p. 57, fig. 2, For. . 2. Authors certificate of the USSR 452061, cl. H 03 K 3/286 (prototype). / E ± / 5г-г ±: // l