Level signal - techintroduce

Basic introduction

The TTL level signal is used most often because the data is usually expressed in binary format. +5V is equivalent to logic "1", and 0V is equivalent to logic "0" This is called TTL (transistor-transistor logic level) signal system, which is a standard technology for communication between various parts of equipment controlled by a computer processor.

TTL level signal is ideal for the data transmission inside the equipment controlled by the computer processor. First of all, the data transmission inside the equipment controlled by the computer processor does not require high power supply and low heat loss. In addition, the TTL level signal is directly connected to the integrated circuit without the need for expensive line drivers and receiver circuits; in addition, the internal data transmission of the equipment controlled by the computer processor is carried out at high speed, and the operation of the TTL interface is just right. Can meet this requirement. In most cases of TTL communication, parallel data transmission is used, and parallel data transmission is not suitable for distances over 10 feet. This is due to both reliability and cost. Because there are problems of phase deviation and asymmetry in the parallel interface, these problems have an impact on reliability; in addition, for parallel data transmission, the cost of cables and connectors is higher than that of serial communication.

Level signal

TTL level definition

Circuit composition

In the digital circuit, the level used by the circuit composed of TTL electronic components.

The first generation of circuits was electronic tubes, and the second generation was transistors (Transistor Transistor Logic). During this period, integrated circuits developed rapidly. There are some interface circuits in the connection between them, which also leads to additional waste. Later, major manufacturers unified the range of the port level of the transistor integrated circuit, which is the TTL level!

Specified range

The level is a voltage range, and the specified output high level>2.4V, output low level<0.4V. At room temperature, the general output high level is 3.5V, and the output low level is 0.2V. Minimum input high level and low level: input high level >=2.0V, input low level <=0.8V, noise tolerance is 0.4V.

The TTL level signal is most commonly used because the data is usually expressed in binary format. +5V is equivalent to logic "1", and 0V is equivalent to logic "0". This is called TTL (transistor -Transistor logic level) signal system, which is a standard technology for communication between various parts of equipment controlled by a computer processor.

Pulse signal and level signal

Level is the "voltage platform", which refers to the high and low state of the voltage at a certain point in the circuit. In digital circuits, high and low levels are commonly used. Ping means "1" or "0" respectively (it can also be "0" or "1"). The level of level is a relative concept, 3V is low level for 7V, but high level for 1V.Pulse refers to the sudden change of the level state in the electronic circuit, which can be a sudden increase (the rising edge of the pulse) or a sudden decrease (the falling edge of the pulse). Generally, after the level of the pulse changes suddenly, the original level state will be restored in a short time.