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Devices programmed . 111KNURE
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.
Date: 2015-01-12; view: 1320
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