Trigger is the simplest device, which is a digital machine. It has two stability states. One of them is assigned the value "1", and the other - "0". The state of the trigger, as well as the value of the binary information that is stored in it, is determined by the output signals: direct and inverse. If the direct output has a potential corresponding to a logical unit, then this trigger state is called a single state (in this case, the signal level at the inverted output corresponds to a logical zero). If there is no potential, then such a device status is called zero.
Trigger types. Classification
- Asynchronous and synchronous triggers are distinguished by the way information is recorded. In asynchronous devices, switching occurs when information signals arrive at the inputs. In synchronous, in addition to the main information, there are also control inputs (one or more). Such triggers switch when they receive control signals.
- According to the information management method, devices are divided into statistical, dynamic, single-stage and multi-stage. The principle of operation of a trigger in statistical control is to switchdevices due to the level of the signal coming to the information inputs, with dynamic control - in changing the potentials coming to the inputs of the semiconductor device. Single-stage devices have one control stage, two-stage devices have two. Synchronous type triggers with single-stage storage of information are called single-cycle, respectively, with two-stage recording - two-cycle.
- JK-flip-flop, RS-flip-flops, T-flip-flop, D-flip-flop and devices of other types are distinguished by the type of implementation of logical connections.
The main parameters of all types of triggers are the maximum duration of the input signal, the delay time required to switch the device, as well as the enabling response time.
Trigger input type designations
- R - means a separate input for setting the device to zero state.
- S - switches the device to single mode.
- K - the input of the split set universal trigger to zero position.
- J - means separate switching of a semiconductor device to a single state.
- T - counter input of the device.
- D - input for switching the trigger to the mode that repeats the level at the input.
- C - device clock input.
- V - manager, allowing entry.
Main types of triggers
- Asynchronous RS flip-flop. This device has two steady states and two inputs - R and S.
- T-trigger is the mosta popular type of semiconductor devices, it has only one information (T) input, it is also called a counting one. The synchronous RS flip-flop has an additional control (C) input.
- D-trigger. Devices of this type also have one information (D) input and represent a time delay.
- DV-flip-flop is, in fact, the same D-flip-flop, but with an additional (V) control input.
- JK trigger. This type of devices differs from asynchronous ones in that when combinations are prohibited for an RS-type device, they invert the stored information.