文档介绍：Combinational logic circuits
Chapter 3
integrated digital circuit
INTRODUCTION
Components level
First IC level (SSI)
Level four
Level three
Level five
Electronic Components, . transistors, diodes, resistors, capacitors
Function Logic Units, . gates, NOT, AND, NAND, EX-OR
Function Logic Units, . adders, counters, multiplexers
More complex Function Logic Units, . microprocessor
Complex Systems, Function Units from levels Two through Four
Third IC level (VLSI)
Second IC level (MSI and LSI)
Level two
Level one
INTRODUCTION
The most common
transistor-transistor logic (TTL)
emitter-coupled logic (ECL)
complementary metal-oxide semiconductor logic (CMOS).
Each of these main logic families is made up of numerous subfamilies.
Bubble-to-Bubble Logic Design
The signal name on a device’s output should have the same active level as the device’s output pin — that is, active-low if the device symbol has an inversion bubble on the output pin, active-high if not.
If the active level of an input signal is the same as that of the input pin to which it is connected, then the logic function inside the symbolic outline is activated when the signal is asserted.
INTRODUCTION
SN54/74ALS00
SN is a prefix. The prefix indicates the manufacturer.
The number 54 indicates a military operating temperature range and 74 indicate a commercial temperature range. Both temperature ranges are available for most functions and subfamilies.
The letter-number combination following the SN54/74 indicates the subfamily and the logical function of the IC.
SN74ALS00 is a commercial temperature range advanced low-power schottky NAND gate IC manufactured by Texas instruments.
NAND Gate as a Universal Logical Element
NOT
AND
OR
Decoder
Decoder convert a set of input variables representing a code into a set of variables representing a different code. The relationship between the input and output codes can be expressed in a truth table.
Encode