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# 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

2.3 Statik registers... 60

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.

 Family Delay (ns) Power Dissipation (mW) Speed-Power Product Standard TTL Low-power TTL High-speed TTL Schottky TTL Low-power Schottky TTL 9.5 Advanced Schottky TTL Advanced low-power Schottky TTL FAST

Date: 2015-01-12; view: 698

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