Download UNIT-IV-LIC

UNIT – IV
SPECIAL ICs
PREPARED BY
V.SANDHIYA
LECT/ ECE
Integrated Circuits
History
• tubes and valves
• transistor - 1947 Bell Labs, Holmdel, NJ
IC Families
How logic gates are configured…
• TTL
• CMOS
IC Families
• TTL - Transistor-Transistor Logic
• CMOS - Complementary Metal Oxide
Semiconductor
IC Families
TTL - Transistor-Transistor Logic
• 74xx designation, i.e., 7447,7490, etc. digital
devices
• Requires 5 volt supply (max. 5.5 volts)
• moderately high current draw
• Includes 74Lxx & 74LSxx designations
(74L47, 74LS47) that have significantly lower
current requirements
IC Families
CMOS - Complementary Metal-Oxide
Semiconductor
• 4000 designation, i.e., 4001, 4511, 4517, etc.
• Works within a range of voltage: 3-15 volts
• Low current requirements
• slightly higher cost than TTL
• very sensitive to static charges (it ruins them)
555
• Introduced in 1972
• Can accurately time from 0.0000011 seconds to
11,000 seconds (just over 3 hours)
• Uses external capacitor and 1 or 2 resistors to
control timing
• Output is always a digital signal (on-off square
wave)
• Contains 28 transistors, 12 resistors
• Requires 4.5 - 18 volts
• Will switch 200mA
555 Timer
DIP chip
Dual
In-Line
Pins
1
8
2
7
3
555
4
6
5
top view
555 Timer
Ground (-)
1
8 +5 to +15VDC
2
7
3
555
4
6
5
top view
• High state output
is always 1.7V less
than supply
• Output is 7.3V @
9V supply
Ground (-)
Output
555 Timer
1
8 +5 to +15VDC
2
7
3
555
4
6
5
top view
555
Monostable timing
• “One shot” timing
• One stable state (off)
• Switches on for duration of time then goes
back to stable (off) state
555
Astable timing
• No stable state (keeps flip-flopping between
states)
• On time called “mark”
• Off time called “space”
• Mark-space timing can be adjusted with
external capacitor and two resistors
Monostable circuit
+9VDC
R1 = 470K
R2 = 1K
7
6
2
8
555
1
4
3
LED
C1 = 47mf
R3 = 330
Monostable circuit
+9VDC
+9VDC
R1 = 470K
R2 = 1K
7
6
2
R2 = 1K
8
555 4
3
1
R1 = 470K
1 8
2 555 7
3 6
4 5
LED
C1 = 47mf
R3 = 330
C1 = 47mf
LED
R3 = 330
Monostable circuit
+9VDC
Timing
Control
Components
R1 = 470K
R2 = 1K
7
6
2
8
555
1
4
3
LED
C1 = 47mf
R3 = 330
Monostable circuit
+9VDC
Output
Components
R1 = 470K
R2 = 1K
7
6
2
8
555
1
4
3
LED
C1 = 47mf
R3 = 330
Monostable circuit
+9VDC
R1 = 470K
R2 = 1K
7
6
2
LED
8
555
1
C1 = 47mf
4
R3 = 330
3
Note LED polarity