Not only
logic (digital) ICs are way
more powerful, compared to analog electronics, but they are also a lot easier to work with. In fact,
designing digital electronics may be as simple as playing with a Lego game. All you need for that is a good
start, and our book LEARN HARDWARE
FIRMWARE AND SOFTWARE DESIGN is, in truth, the
best of the lot!
Now, many logic ICs are standard components, meaning, they are built by many manufacturers. That is
a particularly important aspect when designing hardware, because you are not
constrained to one manufacturer only. Always try to use standard components in
your designs as much as it is (humanly) possible. In addition, you should remember that in firmware we can implement any hardware function. For
example, an 8 pins Microchip controller of about 0.5 USD may be an excellent local driver, replacing few expensive
ICs, and having plenty of upgradeable firmware intelligence. Firmware intelligence should always be preferred to
hardware logic.
In this page are highlighted briefly few standard logic ICs, but you should be aware they are
far more. The structure used
to present families of ICs is:
1. Types of standard ICs
2. Standard Logic ICs
NOTE
The basic notions highlighted in this page are related to
few electronic design topics presented in the first part, Hardware Design, of
LEARN HARDWARE
FIRMWARE AND SOFTWARE DESIGN.
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There are five major types of standard Logic ICs as follows:
1. Resistor Transistor Logic (RTL)
2. Diode Transistor Logic (DTL)
3. Transistor-Transistor Logic (TTL)
4. Emitter Coupled Logic (ECL)
5. Complementary MOS Logic (CMOS)
Only TTL and CMOS types are presented here because they are the most important.
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COMPARISON CHART TTL AND CMOS STANDARD ICs
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Parameter
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TTL |
CMOS |
Designation
74 means industrial range of 0 to +70 Celsius degrees
54 means military range of
-55 to +125 Celsius degrees |
Have members in both categories |
Have members in both categories |
Speed
The speed is measured as the propagation delay of the NAND Gate |
Very fast, up to 3 [ns] |
Fairly fast at 25 ns and lower. |
Power Dissipation
This is the amount of power in [mW] the IC takes from the power supply |
They do take more power, but not very much: 1..19 [mW] |
Very little power consumption at low frequencies, but it
increases greatly at high frequencies. |
| Cost |
Because they were built long time ago, TTLs are the
cheapest of all standard Logic ICs |
Fairly low, and they become permanently cheaper. However,
some highly specialized ICs could be very expensive. |
Fanout
This is the number of loads a Logic IC may supply. However, this term is related to the same family. When
you relate to inter-families of ICs, you need to check the output current supplied--this data is available
in DS |
Very good drivers; they do supply the largest amount of
output current.
Fanout is appx 10 TTL. |
Has the largest fanout in its family due to their high
input impedance.
The inter-families output current supplied, however, is very small (1..2 TTL).
Fanout is over 25 CMOS. |
| Availability |
They are available, but mostly as older models. New models
are developed almost exclusively for the CMOS type. |
Catching up, each day. In addition this is the type that is
developed most. |
| DC voltage supply |
5 [V] |
3..15 [V] |
HIGH logic DC
LOW logic DC |
3..5 [V]
0.2 [V] |
1.7..15 [V]
0 [V] |
| Size |
Mostly DIP packages |
Smallest. Many come as SM (Surface Mount) components. |
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There are many standard ICs. Following are presented just few of the most interesting, but you should study this
subject seriously.
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STANDARD LOGIC ICs
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Family number
|
Description |
| 7406 |
Hex Inverter, buffer driver. |
| 7414 |
Hex Schmitt-Trigger. |
| 7426 |
Dual TTL-CMOS Interface gate |
| 7430 |
8 Input NAND Gate |
| 7441/7442 |
BCD to Decimal Decoder |
| 7444 |
3 Grey code to Decimal Decoder |
| 7446 |
BCD to Seven-Segments Decimal driver (up to 30 V out) |
| 7470 |
Edge triggered J-K Flip-Flop |
| 7473 |
Dual J-K |
| 7475 |
Quad D |
| 7477 |
4 bit Bistable latch |
| 7480 |
Gated Full Adder |
| 7481 |
16 bit active element memory |
| 7483 |
4 bit binary Full Adder |
| 7486 |
Quad XOR Gate |
| 7488 |
256 bit ROM |
| 7490 |
Decade Counter |
| 7491 |
8 bit RAM |
| 7492 |
Divide by 12 Counter |
| 7497 |
Synchronous 6-bit Binary rate multiplier |
| 74100 |
4-bit Bistable Latch |
| 74120 |
Dual pulse Synchronizer/Driver |
| 74121 |
Monostable Multivibrator |
| 74123 |
TTL/Monostable Multivibrator |
| 74126 |
Tri-State Quad buffer |
| 74128 |
50 ohms Line Driver |
| 74123 |
Quad Schmitt Trigger |
| 74133 |
13-Inputs NAND Gate |
| 74138 |
3-to-8 Line Decoder/Demultiplexer |
| 74147 |
Decimal-to-binary Encoder |
| 74151 |
Eight channel Digital Multiplexer |
| 74156 |
Dual 2:4 Demultiplexer |
| 74164 |
8-bit Serial-In Parallel-Out Shift Register |
| 74165 |
8-bit Parallel-In Serial-Out Shift Register |
| 74167 |
Rate multiplier |
| 74172 |
Register File |
| 74181 |
Arithmetic Logic Unit |
| 74183 |
Dual Carry-Save Full Address |
| 74188 |
256-Bit PROM |
| 74190 |
Up-Down Decade Counter |
| 74200 |
256-bit RAM |
The advantage of using standard logic ICs is, they simplify your work a lot, and they come with
very low prices.
LEARN HARDWARE
FIRMWARE AND SOFTWARE DESIGN presents few
excellent applications of standard, logic ICs hardware and firmware implementations. For example, the
SPI BUS,
Multiplexing, Seven-Segments display, SIPO, PISO,
RS232 communications, etc.
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Page last updated on:
August 22, 2008
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