TTL (Transistor Logic Transistor) integrated circuit family

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The history of the TTL integrated circuit family

TTL family (Transistor Logic Transistor) was introduced by the company Texas Instruments (USA) in the year 1965 and has grown continuously by adding new circuits.

It is the most widespread family of digital integrated circuits and has constantly influenced the development of digital equipment. Although currently the area of ​​use of TTL circuits is limited (due to the development of microcontroller applications and type circuits ASIC), the concepts and functional blocks in this family are used in most modern projects.

The TTL family includes logic integrated circuits initially made in bipolar technology, including a number of series of circuits with different values ​​of electrical parameters.

The main series of the TTL family

• normal series (standard): it is denoted by the code 74xxx; 74 characterizes the TTL family in general, and xxx represents numbers through which the function performed by the circuit is defined. There are also circuits marked 54XXX for professional or military applications;
• high speed series: it is denoted by the code 74Hxxx; it is no longer used at present;
• the Low Power series is denoted by the code 74Lxxx; it is made so that the energy consumption from the power supply is as low as possible; it is no longer used at present;
• Schottky series: it is denoted by the code 74Sxxx; is made with Schottky transistors;
• low power Schottky series: 74LSxxx;
• high-performance Schottky series: 74ASxxx; (A-advanced);
• low performance Schottky series: 74ALSxxx.

The last four series are widespread and are used in modern digital equipment. The TTL family logic circuits are manufactured with npn bipolar transistors, operate in positive level logic and are supplied with a positive voltage to ground of 5V.

Course structure

1. LOGIC CIRCUIT AND NOT WITH EMPTY COLLECTOR FROM THE STANDARD SERIES

• Analysis of static operation
• Determination of input current
• Determination of the output current at the gate with empty collector
• Advantages of the empty collector circuit
• Disadvantages of the empty OC circuit
• TTL logic circuit applications with empty collector

2. THE CIRCUIT AND NOT WITH THE STANDARD SERIES COUNTERTIME

• Analysis of static operation
• Analysis of dynamic operation

3. OTHER FUNDAMENTAL CIRCUITS FROM THE STANDARD FAMILY

• OR or NOT circuits from the standard TTL series
• The SI-OR-NO circuit

4. PARAMETERS OF TTL CIRCUITS FROM STANDARD SERIES

• Noise margin
• Maximum guaranteed input currents
• The connection factor
• Power supply
• Average power consumed by a YES-NO circuit
• Propagation time
• The merit factor
• Rules for using the logic circuit from the TTL family
• Applications - control of tasks with TTL circuits with output in time
• LED control
• Control of a high power resistive load

5. OTHER SERIES FROM THE TTL FAMILY

• Fast series (H)
• Low power series (L)
• Schottky Series (S)
• Low Power Schottky Series (LS)
• High-performance series within the TTL family: 74ASxxx; 74ALSxxx

6. CIRCUITS WITH THREE STATES FROM THE TTL FAMILY

7. SCHMITT TRIGGER CIRCUITS FROM THE TTL FAMILY

• Schmitt Trigger Applications