2. Logic Families CompetenciesLogic Families Competencies
61. Without references the student will state what the
acronym TTL stands for with 100% accuracy.
62. Without references the student will state the voltage
levels acceptable to a TTL input for a logic “0” and a logic
“1” with 100% accuracy.
63. Without references the student will state what the
acronym CMOS stands for with 100% accuracy.
64. Without references the student will state the voltage
levels acceptable to a CMOS input for a logic “0” and a logic
“1” with 100% accuracy.
65. Without references, the student will list three
differences between the TTL and CMOS logic families with
100% accuracy.
66. Without references the student will state what the
acronym ECL stands for with 100% accuracy.
3. Logic Families VocabularyLogic Families Vocabulary
TTL (Transistor Transistor Logic) Integrated-circuit technology that
uses the bipolar transistor as the principal circuit element.
CMOS (Complimentary Metal Oxide Semiconductor) Integrated-circuit
technology that uses the field-effect transistor as the principal circuit element.
ECL (Emitter Coupled Logic) Integrated-circuit technology that uses the
bipolar transistors configured as a differential amplifier. This eliminates
saturation and improves speed but uses more power than other families.
4. DIODE TRANSISTOR LOGICDIODE TRANSISTOR LOGIC
Y
What logicfunctionisthiscircuit?
11
01
10
00
YAA
FILL IN THE TRUTH TABLE
DIODE TRANSISTOR LOGIC
B
A
0V
0V
+V
5V
DIODE
DIODE
MMBT3904
1k
1k
5.
6.
7.
8.
9. LOGIC LEVELS / NOISE MARGIN
• Voltage characteristic - defines logical 0
(LOW) or logical 1 (HIGH)
• Noise immunity (noise margin)- logic circuit’s
insensitivity or resistance to undesired
voltages called “noise.”
Input Output
2.0 - 5.5V
LOW GND - 0.8V
HIGH 2.4 - 5.5V (3.5V typical)
GND - 0.4V (0.1V typical)
TTL Voltage Profiles Chart
10. 0%
10%
60%
50%
80%
70%
40%
30%
20%
100%
90%
HIGH
LOW
HIGH
LOW
TTL CMOS
LOW
0 to +3V for CMOS
0 to +0.8V in TTL
Input Voltage Profiles
INPUT VOLTAGE PROFILES-
TTL AND 4000 SERIES CMOS
Undefined
+3 to +7V for CMOS
+0.8V to +2.0V for TTL
Undefined
logic probe reading may
vary depending on
manufacturer
HIGH
+7V to +10V - CMOS
+2V to +5V - TTL
CAUTION
Output V profile differs
Other families V profile differs
+5V +10V
GND
12. OTHER DIGITAL IC SPECIFICATIONS
• Drive Capabilities- sometimes referred to as fan-in or
fan-out.
• Fan out- number of inputs of a logic family that can be
driven by a single output. The drive capability of
outputs.
• Fan in- the load an input places on an output.
• Propagation delay- has to do with the “speed” of the logic
element. Lower propagation delays mean higher speed
which is a desirable characteristic.
• Power Dissipation- generally, as propagation delays
decrease, power consumption and heat generation
increase. CMOS is noted for low power consumption.
13. MOS AND CMOS ICs
• MOS stands for metal-oxide semiconductor.
• PMOS, NMOS, and CMOS are three technologies used to
manufacture ICs.
• NMOS stands for negative-channel metal-oxide semiconductor.
NMOS ICs are faster than PMOS.
• PMOS stands for positive-channel metal-oxide semiconductor.
• CMOS stands for complementary metal-oxide semiconductor.
Both PMOS and NMOS devices are used it its manufacture.
• CMOS ICs are noted for exceptionally low power consumption.
• CMOS ICs were slower than bipolar digital ICs (such as TTL
devices).
• Transmission gates or bilateral switches are unique digital
devices created using CMOS technology.
14. 1. The drive capability of logic device outputs is
sometimes called ___ (fan in, fan out). It is the
number of inputs of a logic family that can be
driven by a single output.
(Left click mouse for questions and answers)
Fan Out
2. CMOS devices are noted for their extremely ___
(high, low) power consumption.
Low
3. A logic device with a low propagation delay
would be considered to be a ___ (high, low) speed
device.
High
4. Several desirable characteristics of logic
devices are good drive capabilities, low power
consumption, and ___ (high, low) propagation
delays.
Low
TEST
15. MOSFETMOSFET
METAL OXIDE SEMICONDUCTORMETAL OXIDE SEMICONDUCTOR
FIELD EFFECT TRANSISTORSFIELD EFFECT TRANSISTORS
P-CHANNEL ENHANCEMENTP-CHANNEL ENHANCEMENT N-CHANNEL ENHANCEMENTN-CHANNEL ENHANCEMENT
TO TURN ON GATE MUST BE
LOWER THAN SOURCE
TO TURN ON GATE MUST BE
HIGHER THAN SOURCE
16. TO TURNON
GATELOWER
THANSOURCE
D
G
S
P-MOS Vout
Vin
C-MOS
P-MOS
N-MOS
TO TURNON
GATEHIGHER
THANSOURCE
G
S
D
N-MOS0V
+V
5V
10k
0V
5V
+V
5V
+V
5V
10k
TO TURNON
GATELOWER
THANSOURCE
D
G
S
P-MOS Vin
TO TURNON
GATEHIGHER
THANSOURCE
G
S
D
N-MOS0V
+V
5V
10k
0V
5V
+V
5V
10k
MOSFETMOSFET
METAL OXIDE SEMICONDUCTORMETAL OXIDE SEMICONDUCTOR
FIELD EFFECT TRANSISTORSFIELD EFFECT TRANSISTORS
