Integrated circuits series 74

pages 20-24

1.4 INTEGRATED CIRCUITS

1.4.1 Families of integrated circuits

Integrated circuits (integrated circuits) are components of digital circuits. An integrated circuit is a semiconductor crystal silicon (chip) that contains electronic components which are manufactured to the gates. The chip is placed in a plastic shell and welded contacts to external terminals (pins) to form the integrated circuit. Figure 1.4.1 shows an integrated circuit package pin double row (Dual In-line Package - DIP).

Figure Shandige

Figure 1.4.1

Chip

Integrated circuits are in a Scale Integration (Scale Integration) as The number of equivalent circuits containing gates. Thus, integrated circuits fall into one of the following categories:

ü SSI (Small Scale Integration) contains fewer than 12 equivalent to a gate circuits

ü MSI (Medium Scale Integration) 12-100 includes a gate equivalent circuits

ü LSI (Large Scale Integration) 100-1000 includes a gate equivalent circuits

ü VLSI (Very Large Scale Integration) 1000-100000 includes more equivalent to a gate circuits

ü ULSI (Ultra Large Scale Integration) includes more than 100000 equivalent to a gate circuits

The logic gates belong to one family (family) of integrated circuits, the best known of which are:

- BIPOLAR

- CMOS (Complementary Metal-Oxide Semiconductor)

- BICMOS (Bipolar CMOS)

- ECL (Emitter Coupled Logic)

The characteristics of logic gates for integrated circuits are:

ð Driving output (Fun Out) is the number of inputs of the integrated circuit can be driven by an outing without jeopardizing the smoothness.

ð Power loss (Power Dissipation) is the power that is consumed by the gates during operation resulting in the production of heat dissipated into the environment.

ð propagation delay (Propagation Delay) is the time to propagate a signal change from entry to exit.

ð Noise Margin (Noise Margin) is the minimum voltage noise causing adverse change in the output.

1.4.2 The number of integrated circuits 74

The integrated circuits 74 of the series is widely used. The name starts with letters relating to the manufacturing company, followed by the number 74, then followed by letters identifying the family and ends with numbers that determine their function.

For example, the chip company is DM74LS00 National Semiconductors (DM) line 74, family BIPOLAR Low Power Schottky (LS) and contains four NAND gates of two inputs (00).

The integrated circuit 74LS00 is shown in Figure 1.4.2.
 

Vcc


4B


4A


4Y


3B


3A


3Y

 

14


13


12


11


10


9


8

 
 

74LS00
 
 
 

1


2


3


4


5


6


7

 

1A


1B


1Y


2A


2B


2Y


GND


Figure 1.4.2

The integrated circuit 74LS00

Table 1.4.1 shows the external terminals (pins) of the integrated circuit 74LS00 and their importance. There are 14 pins: 12 pins for the inputs and outputs of NAND gates four containing the integrated circuit and 2 pins to power.

Table 1.4.1

The 14 external terminals (pins)

the integrated circuit 74LS00

Pin


Significance

1


1A


first entrance gate 1

2


1B


second entrance gate 1

3


1Y


output gate 1

4


2A


first entrance gate 2

5


2B


second entrance gate 2

6


2Y


exit gate 2

7


GND


grounding

8


3Y


exit gate 3

9


3A


first entrance gate 3

10


3B


second entrance gate 3

11


4Y


exit gate 4

12


4A


first entrance gate 4

13


4B


second entrance gate 4

14


Vcc


supply voltage

1.4.3 Reasonable prices and power station

Integrated circuits recognize the inputs of voltages, which correspond to the logical "0" or "1". Also, give them to the outputs voltages corresponding to logic "0" or "1".

But in practice it is not possible to have completely accurate voltages. This happens for several reasons, including fluctuations in supply voltage, temperature effects and noise in the circuit operation and effect of load output voltage. For this reason, two bands defined by voltages, high corresponding to logical "1" and low corresponding to logical "0". Between these two zones is a zone of singles. A voltage that is in this zone can be seen from the circuit or as a logical "0" or a logical "1" and so the integrated behavior is unpredictable. The areas of the trends mentioned in data sheets (Data Sheets) manufacturers. For example, the integrated circuit 7400 recognizes inputs as a logical "0" the voltage range from 0 Volts to 0.8 Volts and a logical "1" the voltage range from 2 Volts to 5 Volts, as shown in Figure 1.4.3. The values for the output voltages is from 0 Volts to 0.4 Volts for logic "0" and up to 2.7 Volts 5 Volts for logic "1" as shown in Figure 1.4.4.

 

Figure 1.4.3

Values for the input voltages

Figure 1.4.4

Values for the output voltages

1.4.4 Instructions on the study data sheets

To understand how to study the data sheet (Data Sheets) of integrated circuits will study the IC 74LS00.

The data sheet included in the above integrated LS / S / TTL DATA BOOK.

The first page provides information about the content of the completed: Quad 2 Input Gates (four gates AND 2 inputs). Also shown in Figure connections (Connection diagram), the logic function Y = A × B and the truth table (Function Table).

The second page shows the maximum absolute values (absolute maximum ratings), the recommended operating conditions (recommended operation conditions), the electrical characteristics (electrical characteristics) and typical switching (switching characteristics).

The maximum absolute values on the supply voltage, input voltage, the temperature range of storage and operating temperature range. Values greater than these can destroy the IC.

The recommended operating conditions on the parameter values suggested by the manufacturer, ie the supply voltage (Vcc), the voltage at the entrance to a low level (VIL), the input voltage for high level (VIH), output current for low (IOL), the output current for high level (IOH) and temperature range of the operating environment (TA)

The electrical characteristics are the values obtained for the following parameters for specific modes of integrated:

- Voltage "strangulation" entry (VI)

- Voltage output high level (VOH)

- Voltage output low (VOL)

- Input (II)

- Input for high level (IIH)

- Input for Low (IIL)

- Short-circuit output current (IOS)

- Stream OK the outputs at high level (ICCH)

- Stream OK with low level outputs (ICCL)

The switching characteristic shows the reaction rate of the integrated output to the change in input, ie the propagation delay.

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