1. INTEGRATED CIRCUIT LOGIC FAMILY
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2. Introduction
ICs have made digital systems more reliable by reducing the number of external interconnection from one device to another.
ICs have reduced the amount of electrical power needed to perform a given function.
IC cannot handle very large currents or voltages because the heat generated in such small spaces would cause temperature to rise beyond acceptable limits
ICs are principally used to perform low-power circuit operations that are commonly called information processing.
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3. Introduction
Rapidly growth from SSI, with fewer than 12 gates per chip; through MSI, with 12 to 99 equivalent gates per chip
Others – LSI, VLSI, ULSI and GSI
There are some things IC cannot do – when deal with very large current
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4. Digital IC Terminology
VIH (min) – High level input voltage. The minimum level required for a logical 1 at an input. Any voltage below this level will not be accepted as a HIGH by the logic circuit
VIL (max) – The maximum input voltage for logic zero
VOH (min) – The minimum voltage level at a logic circuit output in the logic 1 state under defined load conditions
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5. Digital IC Terminology (cont.)
VOL (max) – Low level output voltage. The maximum voltage level at a logic circuit output in the logical 0 state under defined load conditions
IIH – High level input current. The current that flows into an input when a specified high level voltage is applied to that input
IIL – Low level input current. The current that flows into an input when a specified low level voltage is applied to that input
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6. Digital IC Terminology (cont.)
IOH – High level output current
IOL – Low level output current
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7. Exercise Describe the input and output logic for IC 7442
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8. Fan out Also known as loading factor
Defined as the maximum number of logic inputs that an output can drive reliably
A logic circuit that specify to have 10 fan out can drive 10 logic inputs
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9. Propagation delay
Two types of propagation delay – tPLH , delay time in going from logical 0 to 1; tPHL delay from 1 to 0
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10. Noise Immunity

11. Noise Immunity (cont.) The high state noise margin VNH is defined as
VNH = VOH (min) – VIH (min)
The low state noise margin VNL is defined as
VNL = VIL (max) – VOL (max)
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12. Power Requirements
Every IC need a certain power requirement to operate
This power supply is come from the voltage supply that connected to the pin on the chip labeled VCC(TTL) or VDD(MOS)
The amount of power require by ICs is determined by the current that it draws from the VCC
The actual power is ICCxVCC
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13. Cont. ICC(avg) = (ICCH + ICCL)/2 PD(avg) = ICC(avg)Xvcc
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14. The TTL Logic Family
FIGURE (a) Basic TTL NAND gate; (b) diode equivalent for Q1.
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15. TTL NOR gate
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16. TTL Data sheet
In 1964, Texas Instruments corporation introduced the first line of standard TTL ICs
The 54/74 series, most widely used IC logic families
The difference between 54 and 74 series is a range of temperatures
IC number is the same with all series produce by different manufactures
Each manufacturer however usually used the prefix that represent the special words – Texas Instrument uses the prefix SN, National semiconductor uses DM etc
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17. Supply Voltage and Temperature Range
74ALS series and the 54ALS series use nominal supply voltage (VCC) of 5V, but can tolerate a supply variation of 4.5 to 5.5V.
74ALS series can operate properly in ambient temperatures ranging from 0 to 70 degrees C, while the 54ALS series can handle -55 to +124 degree C.
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18. Voltage Levels
Input and output voltage levels can be found on the data sheet.
The min and max values shown are for worst case conditions of power supply, temperature and loading conditions

19. TTL Series Characteristics
We have found the type of ICs – 74, 74LS, 74ALS before
LS – low power Schottky, ALS – advance low power Schottky
The function is same, but the difference is on the characteristic

20. TTL Data Sheet

21. TTL Series Characteristics
74 series of TTL – offers a wide variety of gates and flip flops
Consist of:
a. Standard TTL, 74 series – no longer be use
b. Schottky TTL, 74S series
c. Low-power Schottky TTL, 74LS Series
d. 74AS
e. 74ALS and 74F
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22. Schottky TTL, 74S Series
7400 series operates using saturated switching in which many of the transistors, when conducting will be in saturated condition
This can causes a storage time delay ts when the transistors switch from ON to OFF and effect the speed
74S series come to solve the speed problem
It accomplishes this by using a Schottky barrier diode (SBD)
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23. Schottky TTL, 74S Series (cont.)
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24. Advances Schottky TTL, 74AS series
74AS give more advance on speed switching of TTL ICs at much lower consumption
The comparison is shown in the following table for a NAND gate in each series
74S
74AS
Propagation delay
Power dissipation
Speed-power product
3ns
20 mW
60 pJ
1.7ns
8 mW
13.6 pJ
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25. Advanced Low Power Schottky TTL, 74ALS Series
Improved on both speed and power dissipation
74S
74AS
Propagation delay
Power dissipation
Speed-power product
9.5 ns
2 mW
19 pJ
4 ns
1.2 mW
4.8 pJ
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26. Example
Use table 8-6 to calculate the dc noise margins for a typical 74LS IC. How does this compare with the standard TTL noise margins ?
Solution
74LS
VNH = VOH(min) – VIH(min)
= 2.7 – 2.0
= 0.7 V
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27. TTL Loading and Fan Out
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