Devices programmed………………………………………………………. 111

KNURE

Department of CE

Lectures on

COMPUTER ELECTRONICS

Part 2

Semiconductor devices in computers

Composed by R.Umyarov

Kharkov 2002

Combination Circuits………………………………………………… 5

Circuitry TTL-elements with Shottky diodes……………………………… 5

Element with the open collector…………………………………………… 8

Emitter-coupled logic (ECL)………………………………………………. 10

Decoder…………………………………………………………………….. 15

Coder units………………………………………………………………… 26

Multiplexers (Selectors)…………………………………………………… 32

Multiplexer Trees…………………………………………………………. 34

Demultiplexers (Distributors)……………………………………………… 36

Applicanion of multiplexer………………………………………………… 38

Code converters…………………………………………………………… 39

Shifters……………………………………………………………………. 43

Comparators………………………………………………………………. 49

Sequentional Circuits………………………………………………… 53

2.1 Circuritry of flips…………………………………………………………… 53

2.2 Flips types…………………………………………………………………. 58

Shift register……………………………………………………………….. 62

Counters……………………………………………………………………. 67

Synchronous reversal counters…………………………………………….. 77

Schmitt flip-flops………………………………………………………….. 80

Memory Devices………………………………………………………. 85

Circuitri of memori element………………………………………………… 85

Mask-type LIC of the ROM………………………………………………… 86

3.3 ROM with singl programming……………………………………………… 96

Memori element with electrical erase………………………………………. 101

Static RAM…………………………………………………………………. 103

Dynamic RAMs……………………………………………………………. 108

Devices programmed………………………………………………………. 111

1 Combination Circuits

1.1 Circuitry TTL-elements with Shottky diodes

A diode in the base-collector junction of the tran­sistors that prevents them from going into saturation and, therefore, reduces the switching time out of saturation. To perform this function, the diode has to have a low voltage between its terminals; Schottky diodes have this property. The diode is constructed as part of the transistor, resulting in what is called the Schottky transistor.

The low-power Schottky TTL family has higher resistance values than the Schottky TTL. This has the effect of reducing the power consumption and increasing the delay. This family has a good speed-power product and therefore is widely used.

Improvements have been made in the technology producing variations of the Schottky TTL with better speed-power products. Examples of these are Texas Instruments Advanced Schottky (AS), Advanced Low-power Schottky (ALS), and Fairchild Advanced Schottky (FAST). Table 1.1 gives a summary of the power consumption, delay, and speed-power product of all variations.

Table 1.1- Characteristics of TTL Variations.

Date: 2015-01-12; view: 1177