Lab 2 Revisited Exercise - MIT OpenCourseWare · 6.091 IAP 2008 Lecture 3 10 Zener Diode • Zener...
Transcript of Lab 2 Revisited Exercise - MIT OpenCourseWare · 6.091 IAP 2008 Lecture 3 10 Zener Diode • Zener...
6.091 IAP 2008 Lecture 3 1
Lab 2 Revisited Exercise
• Wire up led display • Note the ground leads• LED orientation
1K
100k
+15V
2N2222
6.091 IAP 2008 Lecture 3 2
Comparator, Oscillator
Vo
V-
V+Vin
+5
1k2
3
6
+15
7
4
Notice that power connections are shown; bypass capacitors included for power supply filtering.
All voltage measurements are referenced to ground
6.091 IAP 2008 Lecture 3 3
Op-Amps
Vo
V-
V+
Vin
C
R1
Vo
V-
V+
Vin
R2
R1
ino vRRv
12
−= ∫−= dtRCvv in
o
Inverting Amplifier Integrator
For clarity, power connections and bypass capacitors not shown.
Vo
V-
V+
Vin
10k
1k
1
5
-15V
10k
Null Adjustment
6.091 IAP 2008 Lecture 3 4
Lab Exercise - Schmitt Trigger
Vo
V+
V-
R2
R1
Vin
• Schmitt trigger have different triggers points for rising edge and falling edge.
• Can be used to reduce false triggering
• This is NOT a negative feedback circuit.
6.091 IAP 2008 Lecture 3 5
Notes
• IC power supply connections generally not drawn. All integrated circuits need power!
• Use standard color coded wires to avoid confusion.
Potentiometer internals
6.091 IAP 2008 Lecture 3 6
Power Supplies, Voltage Regulators
• Conventional Power Supply– rectify (convert AC to
DC)– filter out the ripple– regulate the voltage
• 3 terminal IC regulator
3 terminal regulator
.
6.091 IAP 2008 Lecture 3 7
Wire Gauge• Wire gauge: diameter is inversely
proportional to the wire gauge number. Diameter increases as the wire gauge decreases. 2, 1, 0, 00, 000(3/0) up to 7/0.
• Resistance– 22 gauge .0254 in 16 ohm/1000 feet– 12 gauge .08 in 1.5 ohm/1000 feet– High voltage AC used to reduce loss
6.091 IAP 2008 Lecture 3 8
78XX Voltage Regulator+5V, +12V, +15V-5V, -12V, -15V
Reprinted with permission of National Semiconductor Corporation.
6.091 IAP 2008 Lecture 3 9
7805 Circuit
Reprinted with permission of National Semiconductor Corporation.
6.091 IAP 2008 Lecture 3 10
Zener Diode• Zener diodes will maintain a
fixed voltage by breaking down at a predefined voltage (zenervoltage).
4.7k
Lab exercise• Wire up the above circuit with a 1N752A (5.6V)
zener. • Set the FG for a 0-10V ramp. Display the
output of the FG and the voltage across the zener on the oscilloscope. Describe what is happening.
6.091 IAP 2008 Lecture 3 11
Adjustable Voltage Source
Vo
V+
V-
+15V
0.1uf
10K1N758
10v
270Ω
6.091 IAP 2008 Lecture 3 12
Adjustable Voltage Power Supply
+15V
1N758
10v
270Ω0.1uf
10K
Vo
V+
V-
.
1uf
6.091 IAP 2008 Lecture 3 13
LM317 Three Terminator Adjustable Voltage Regulator
• First 3 terminal adjustable voltage regulator• 1.2 - 25 Voltage output range• Short circuit protected• Thermal shutdown
Reprinted with permission of National Semiconductor Corporation.
6.091 IAP 2008 Lecture 3 14
LM317
Reprinted with permission of National Semiconductor Corporation.
6.091 IAP 2008 Lecture 3 15
Buck Converters
• Linear power supplies are very inefficient
• Power dissipated by regulating element
• Buck converters operating in switching mode (on/off)
+
.
6.091 IAP 2008 Lecture 3 16
555 Timers• Simple, versatile, low
cost IC for timing applications: oscillators,
+
_
+
_
1
2
6
5
5k
5k
5k
3
7
8
4
VCC
Threshold
Control Voltage
Trigger
Output
Discharge
Gnd Reset
CompA
CompB
FlipFlop
Inhibit/Reset
R
S
Q
one-shot pulse generator, pulse width modulator, missing pulse detector
• Circuit: two comparators, flip flop, resistor divider and a discharge transistor.
Figure by MIT OpenCourseWare.
ready
6.091 IAP 2008 Lecture 3 17
555 Block Diagram
Figure by MIT OpenCourseWare.S R Reset Output
1 1 1 last state
0 1 1 low
1 0 1 high
0 0 1 high
NA NA 0 low
ready
+
_
+
_
1
2
6
5
5k
5k
5k
3
7
8
4
VCC
Threshold
Control Voltage
Trigger
Output
Discharge
Gnd Reset
CompA
CompB
FlipFlop
Inhibit/Reset
R
S
Q
6.091 IAP 2008 Lecture 3 18
Vc
RC Equation
dtdVC c
cc V
dtdVRC +
Vs = 5 V
Switch is closed t<0
Switch opens t>0
Vs = VR + VC
Vs = iR R+ Vc iR =
Vs =
R
C
Vs = 5 V
⎟⎟⎞
⎜⎜⎛−=
−RCt
sc eVV 1⎠⎝
⎟⎟⎠
⎞⎜⎜⎝
⎛−=
−RCt
c eV 15
6.091 IAP 2008 Lecture 3 19
Monostable Circuit
Comp
555 or 1/2 556
Comp
Flip flop Output Output
Reset
R
R
R
Discharge
Control voltage
Threshold
Trigger
Ra
VCC
C
Reprinted with permission of National Semiconductor Corporation.Figure by MIT OpenCourseWare,
based on Philips Semiconductors datasheet.
6.091 IAP 2008 Lecture 3 20
Oscillator (Astable)
Reprinted with permission of National Semiconductor Corporation.
Figure by MIT OpenCourseWare,based on Philips Semiconductors datasheet.
Comp
555
Comp
Flip flop Output
Reset
R
C
R
R
RA
Discharge
Control voltage
Threshold
Trigger
Rb
VCC
1 4
2
36
5
7
8
6.091 IAP 2008 Lecture 3 21
Closet Light Timer – Lab Exercise
+15+15
+15 8
1
reset
trigger
control
threshold
discharge
output10k1k
0.1uf
0.01uf
1k
R
C
555
Switch closed = door closedton = 1.1RC
6.091 IAP 2008 Lecture 3 22
Lab Exercise
• Wire up zener diode circuit• Build variable voltage power supply• Build variable current source• Build 555 oscillator• Build closet light timer
6.091 IAP 2008 Lecture 3 23
Analog Circuit Summary
• 3 Terminal Regulators• Zener Diodes• Power Supplies• 555 Timers & circuits
6.091 IAP 2008 Lecture 3 24
Important Missing Links
• The real world is an analog world. However, computing is best performed via digital systems (i.e. the processing of data with 0’s and 1’s).
• Digital-Analog Conversion• Analog-Digital Conversion
6.091 IAP 2008 Lecture 3 25
Analog vs Digital
• Analog systems/devices work with information in a continuous stream: clock with hands, mercury thermometer, vinyl records, analog meters, calipers.
• Digital systems/devices work with information in a discontinuous stream (0,1): digital thermometer, digital meters, computers.
6.091 IAP 2008 Lecture 3 26
Music – An Example
• CD’s are digital systems that sample and stores audio data– sampling rate: 44.1 khz– data stored in 16 bit format; implies
216 = 65,536 possible output levels
• DVD Audio samples at 96-192kHz/24 bits
• Analog records have an infinite number of output levels.
6.091 IAP 2008 Lecture 3 27
D-A Conversion (DAC)• Problem: take a digital signal and convert to an analog voltage: R-2R ladder
0001 -> 1/16 * 5 volt 0010 -> 2/16 * 5 volt0011 -> 3/16 * 5 volt. . .1101 -> 14/16 * 5 volt1111 -> 15/16 * 5 volt
• Note that the outputs are at discrete levels – not continuous!
R
R
+5
R
+5
R
+5
R
+5
2R 2R 2R 2R
Vo
Bo B3B2B1
⎥⎦⎤
⎢⎣⎡ +++ 031223 2
121
21
21 BBBB 5
6.091 IAP 2008 Lecture 3 28
Digital Circuits• Real world analog signals have noise – unavoidable.• Digital circuits offers better noise immunity.• Use voltage to represent “0” and “1”
– Avoid forbidden voltage zone.– Make standards tighter for output than for inputs.
• Data (HCMOS family): 0 (low), 1 (high) – Input voltage low: 0.0 – 0.7v– Input voltage high: >2.0V– Output low: <0.4v– Output high: >3.98v
6.091 IAP 2008 Lecture 3 29.
Digital Circuits
HCMOS 1 (high) – Output high: >3.98v– Input voltage high: >2.0V
output highrange
input highrange
+5V
+3.98V
+2.0V
0.7V
0.4Vinput low
rage
output lowrange
noisemargin
noisemargin
Forbidden Zone
HCMOS 0 (low)– Output low: <0.4v– Input voltage
low: 0.0 – 0.7v
6.091 IAP 2008 Lecture 3 30
Power Requirements• The following power supplies are common for analog
and digital circuits:
+5v for digital circuits, +15v, -15v for analog,-5v, +12v, -12v also used
• Other voltages generally derived.
6.091 IAP 2008 Lecture 3 31
Boolean AlgebraA B = A & B
A = Inverse of A
A B = Inverse of [A&B]
DeMorgan's Law
A B = A + B
A + B = A & B
6.091 IAP 2008 Lecture 3 32
Digital System Implementation• Start with AND, OR, NOR, NAND gates and
add more complex building blocks: registers, counters, shift registers, multiplexers. Wire up design. High manufacturing cost, low fix costs. Examples 74LS, 74HC series IC
• For volume production, move to PALs, FPGAs, ASICs. Low manufacturing cost, high fix costs.
6.091 IAP 2008 Lecture 3 33
Basic Gates
Circle indicates inversion
6.091 IAP 2008 Lecture 3 34
74LS00 NAND Gate
1 2 3 4 5 6 7
A1 B1 Y1 A2 B2 Y2 GND
VCC
Dual-In-Line Package
14 13 12 11 10 9 8
B4 A4 Y4 B3 A3 Y3
This device contains four independent gates eachof which performs the logic NAND function.
Figure by MIT OpenCourseWare, adapted from the National Semiconductor 54LS00 datasheet.
6.091 IAP 2008 Lecture 3 35
74LS02 NOR Gate
1 2 3 4 5 6 7
Y1 A1 B1 Y2 A2 B2 GND
VCC
Dual-In-Line Package
14 13 12 11 10 9 8
Y4 B4 A4 Y3 B3 A3
This device contains four independent gates eachof which performs the logic NOR function.
Figure by MIT OpenCourseWare, adapted from the National Semiconductor 54LS02 datasheet.
6.091 IAP 2008 Lecture 3 36
74LS08 AND Gate
1 2 3 4 5 6 7
A1 B1 Y1 A2 B2 Y2 GND
VCC
Dual-In-Line Package
14 13 12 11 10 9 8
B4 A4 Y4 B3 A3 Y3
This device contains four independent gates eachof which performs the logic AND function.
Figure by MIT OpenCourseWare, adapted from the National Semiconductor 54LS08 datasheet.
6.091 IAP 2008 Lecture 3 37
Building Logic
• From basic gates, we can build other functions: Exclusive OR Gate
X Y Z0 0 00 1 11 0 11 1 0
XZ
Y
X
Y Z
6.091 IAP 2008 Lecture 3 38
74LS86 Exclusive OR
Figure by MIT OpenCourseWare, based on Motorola datasheet.
In
Truth Table
A
L
L
L
L
H H
H
H
H
H
L L
B Z
Out
1 2 3 4 5 6 7
14 13 12 11 10 9 8
GND
VCC