Upload
gurpreet-singh
View
222
Download
0
Embed Size (px)
Citation preview
8/14/2019 TI Type 502 Flip Flop: 1st
1/22
CENT-113 Digital Electronics1
Flip Flops
TI Type 502 Flip Flop: 1st production IC in 1960.
8/14/2019 TI Type 502 Flip Flop: 1st
2/22
CENT-113 Digital Electronics2
Interest
1919: W. H. Eccles and F. W. Jordan publish the firstflip-flop circuit design.
M74HC74AM Fairchild CMOS flip-flop for frequency
manipulation is used in a Smart Card Reader.
8/14/2019 TI Type 502 Flip Flop: 1st
3/22
CENT-113 Digital Electronics3
Logic Circuit Classifications
Combination Logic CircuitsBuilding block is the logic gate.
Use AND, OR, NOT gates.
Sequential Logic CircuitsBuilding block is the flip flop (FF).
Used in timing and memory devices.
Flip Flops are wired to form counters, shift registers,and various memory devices.
8/14/2019 TI Type 502 Flip Flop: 1st
4/22
CENT-113 Digital Electronics4
R-S Flip Flop
Logic Symbol Wiring DiagramSet
Reset Complementary
NormalS
R
Q
Q
FF
Truth Table Waveform DiagramMode of
Operation
Input
S
Input
R
Output
Q
Output
Q
Effect
Prohibited 0 0 1 1 ProhibitedDo not use
Set 0 1 1 0 For settingQ to 1
Reset 1 0 0 1Resetting
Q to 0
Hold 1 1 Q Q DependsPreviousState
Input Output
Input
Output
Set Reset SetHold
S
R
Q
Q
Hold
1
0
1
0
1
0
1
0
Also called:R-S Latch
Set-Reset FF
8/14/2019 TI Type 502 Flip Flop: 1st
5/22
CENT-113 Digital Electronics5
Clocked R-S Flip Flop
Logic Symbol Wiring Diagram
Truth Table Waveform DiagramMode of
Operation
Input
CLK
Input
S
Input
R
Output
Q
Output
Q
Effect
Hold 0 0 1 1 NoChange
Reset 0 1 0 1Reset or
cleared to0
Set 1 0 1 0 Set to 1
Prohibited1 1 1 1 Do notuse
Input
Output
S
R
Q
Q
1
0
1
0
1
0
1
0
Set
Reset Complementary
NormalInput Output
ClockS
R
Q
Q
FF
CLK
CLK
Output FF operates
Synchronouslyin step with clock.
8/14/2019 TI Type 502 Flip Flop: 1st
6/22
CENT-113 Digital Electronics6
Questions
Q. What type of waveform is used in flip flops? A. Square Waves.
Q. What does the RS stand for in the RS Flip
Flop? A. Reset Set.
8/14/2019 TI Type 502 Flip Flop: 1st
7/22
CENT-113 Digital Electronics7
D Flip Flop
Logic Symbol Wiring DiagramData
Clock Complementary
NormalD
CLK
Q
Q
FF
Truth Table Similar Wiring
Input Output
Also called:
Delay FFData FF
D-type Latches
Delayed 1
Clock Pulse
Input
CLK
Input
D
Output
Qn+1Output
Q
0 0 11 1 0
D
CLK
Q
Q
FF
S
R
Q
Q
FF
CLK
=
8/14/2019 TI Type 502 Flip Flop: 1st
8/22
CENT-113 Digital Electronics8
7474 D Flip Flop
Logic Symbol
Truth Table
Data
Clock Complementary
NormalD
CLK
Q
Q
FFInput Output
Mode of
Operation
INPUTS OUTPUTS
Asynchronous Synchronous
PS CLR CLK D Q Q
Asynchronous Set 0 1 X X 1 0
Asynchronous Reset 1 0 X X 0 1
Prohibited 0 0 X X 1 1
Set 1 1 L to H 1 1 0
Reset 1 1 L to H 0 0 1
Note: The asynchronous inputs
(PS & CLR) Override thesynchronous inputs (D & CLK) .
PS
Preset
Clear
CLR
8/14/2019 TI Type 502 Flip Flop: 1st
9/22
CENT-113 Digital Electronics9
D (Delay) Flip Flop Uses
Sequential logic devices used in temporarymemory devices.
Wired together to form shift registers and storage
registers. Delays data from reaching output Q one clock
pulse.
CMOS examples: 74HC74, 74FCT374, 40174 Over 50 different ICs in FACT CMOS family.
8/14/2019 TI Type 502 Flip Flop: 1st
10/22
CENT-113 Digital Electronics10
J-K Flip Flop
Logic Symbol
Truth Table
Mode of
OperationINPUTS OUTPUTS Effect
Input
CLK
Input
J
Input
K
Output
Q
Output
Q
Hold 0 0 NoChange
No
Change
No
Change
Reset 0 1 0 1 Reset orcleared to 0
Set 1 0 1 0 Set to 1
Toggle 1 1 Toggle Toggle Changed toOpposite State
Data
Complementary
Normal
Input Output
ClockJ
K
Q
Q
FF
CLK
Data
8/14/2019 TI Type 502 Flip Flop: 1st
11/22
CENT-113 Digital Electronics11
7476 J-K Flip Flop
Logic Symbol
Truth Table
Mode of
Operation
INPUTS OUTPUTS
Asynchronous Synchronous
PS CLR CLK J K Q Q
Asynchronous Set 0 1 X X X 1 0
Asynchronous Reset 1 0 X X X 0 1
Prohibited 0 0 X X X 1 1
Hold 1 1 0 0 No Change No Change
Reset 1 1 0 1 0 1
Set 1 1 1 0 1 0
Toggle 1 1 1 1 Opposite State
Note: 7476 uses the entire pulse to
transfer data from J & K data inputsto Q & Q outputs.
Data
Complementary
NormalInput Output
Clock J
K
Q
Q
FFCLK
Data
Preset
Clear
CLR
8/14/2019 TI Type 502 Flip Flop: 1st
12/22
8/14/2019 TI Type 502 Flip Flop: 1st
13/22
CENT-113 Digital Electronics13
Questions
Q. What circuit can be used to give a clocksignal?
A. Astable multivibrater.
8/14/2019 TI Type 502 Flip Flop: 1st
14/22
CENT-113 Digital Electronics14
IC LatchesInput
Keyboard
7 8 9
1
4 5 6
2 3
0
Encoder 4-Bit Latch Decoder
Output
Display
Decimal DecimalBinary
A device that serves as a temporary buffer memory
is called a latch. An example of a 4-bit latch is the
7475.A latch is transparent when the enable input is high,
the normal outputs follow the data in the D inputs.One example of flip flops is to latch or hold data.
8/14/2019 TI Type 502 Flip Flop: 1st
15/22
CENT-113 Digital Electronics15
IC Latch Uses
The latch is the fundamental memory deviceused in digital electronics.
Almost all digital equipment contains simple
memory devices called latches. CMOS examples: 4042, 4099, 74HC75
4043 is an example of a BCD-7 Segment
latch/decoder/driver chip.
8/14/2019 TI Type 502 Flip Flop: 1st
16/22
CENT-113 Digital Electronics16
CMOS D Flip-Flop Schematic
8/14/2019 TI Type 502 Flip Flop: 1st
17/22
CENT-113 Digital Electronics17
D Flip Flop using Nor gatesWhat logic gates are more efficient?
8/14/2019 TI Type 502 Flip Flop: 1st
18/22
CENT-113 Digital Electronics18
CMOS D Flip-Flop
CMOS technology allows a very differentapproach to flip-flop design and construction.
Instead of using logic gates to connect the clock
signal to the master and slave sections of the flip-
flop, a CMOS flip-flop uses transmission gates
to control the data connections.
8/14/2019 TI Type 502 Flip Flop: 1st
19/22
CENT-113 Digital Electronics19
Triggering Flip Flops
The added inverter bubble at the clock inputshows that triggering occurs on the negative
going edge of the clock pulse.
The J-K master/slave flip flop uses the entirepulse (positive edge and the negative edge) to
trigger the flip flop.
Waveform 165.
8/14/2019 TI Type 502 Flip Flop: 1st
20/22
CENT-113 Digital Electronics20
Schmidt Trigger
Schmidt Trigger Inverter commonly used tosquare up input signal. This reshaping of the
waveform is called signal conditioning.
8/14/2019 TI Type 502 Flip Flop: 1st
21/22
CENT-113 Digital Electronics21
IEEE vs. Logical Symbols
See internet links.
8/14/2019 TI Type 502 Flip Flop: 1st
22/22
CENT-113 Digital Electronics22
Conclusions
Q. What are some circuit uses for flip flops? A. Counters, shift registers, and various memory
devices.