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Digital I/O
Transistors and Mosfets
CMPE 118 MECHATRONICS
Bipolar Transistors used as Switches
NPN
Collector
Base
PNP
Emitter
Base
Emitter
Collector
How do we get them turned on?
Forward bias the Base:Emitter Junction
Supply current
How much current?
1/10th as much as the Collector:Emitter current
How do we know if we have been successful?
Vce will drop to about 0.2V
CMPE 118 MECHATRONICS
Bipolar Transistors used as Switches
How do we get them turned on?
How do we know if we have been successful?
CMPE 118 MECHATRONICS
MOSFET Transistors used as Switches
N-Channel
Drain
Gate
P-Channel
Drain
Gate
Source
Source
How do we get them turned on?
|VGS| > Threshold N-Channel: G > S, P-Channel G < S
How do we know if we have been successful?
RDS will drop to a low value
CMPE 118 MECHATRONICS
MOSFET Transistors used as Switches
How do we get them turned on?
How do we know if we have been successful?
CMPE 118 MECHATRONICS
What is CMOS ?
Complementary MOS
N-Channel and P-Channel used in Pairs
CMPE 118 MECHATRONICS
What is CMOS ?
CMPE 118 MECHATRONICS
Digital Inputs
Logic Levels
0
1
Voltage Levels
< Low Threshold
CMPE 118 MECHATRONICS
> High Threshold
What Are the Voltage Levels?
That Depends on
the type of logic...
Transistor Transistor Logic
High-speed CMOS
High-speed CMOS, TTL input
Original CMOS
CMPE 118 MECHATRONICS
How is the Voltage Specified?
Recommended Operating Conditions
Symbol
DM54LS00
Parameter
Min
VCC
V IH
SupplyVoltage
High Level Input Voltage
V IL
IOH
Low LevelInput Voltage
High Level Output Current
IOL
TA
Low LevelOutput Current
Free Air Operating Temperature
CMPE 118 MECHATRONICS
4.5
2
-55
Nom
5
DM74LS00
Max
5.5
Min
V
V
0.7
-0.4
0.8
- 0.4
V
mA
4
8
mA
70
°C
0
5
Max
5.25
125
4.75
2
Nom
Units
It takes
Voltage and Current
to make a device work
Electrical Characteristics
Symbol
Parameter
VI
Input Clamp Voltage
V OH
V OL
over recommendedoperating free airtemperature range (unlessotherwise noted)
Conditions
Typ
(Note 1)
Max
Units
- 1.5
V
High LevelOutput
Voltage
VCC = Min, II = - 18 m A
VCC = Min, IOH = Max,
V IL = Max
DM54
DM74
Low Level Output
Voltage
VCC = Min, IOL = Max,
VIH = Min
DM54
DM74
0.25
0.35
0.4
0.5
IOL = 4 mA, VCC = Min
V CC = Max,VI = 7 V
DM74
0.25
0.4
II
Input Current @ Max
Input Voltage
I IH
I IL
High LevelInput Current
Low Level Input Current
I OS
Short Circuit
Output Current
I CCH
Supply Current with
Outputs High
VCC = Max
Supply Current with
Outputs Low
CMPE 118 MECHATRONICS
VCC = Max
I CCL
Min
V CC = Max,VI = 2.7V
V CC = Max,VI = 0.4V
V CC = Max
(Note 2)
DM54
DM74
2.5
2.7
3.4
3.4
- 20
- 20
V
V
0.1
mA
20
- 0.36
A
mA
- 100
- 100
mA
0.8
1.6
mA
2.4
4.4
mA
InterConnecting
CMPE 118 MECHATRONICS
Digital Logic
CMPE 118 MECHATRONICS
Bipolar TTL Output
Digital Logic
Open Collector Output
VCC
6k
3.4 k
1.6 k
Input A
Output Y
100
1k
GND
Resistor values shown are nominal.
CMPE 118 MECHATRONICS
Digital Logic
CMPE 118 MECHATRONICS
CMOS Totem Pole
Sizing a pull-up Resistor: Max & Min.
+5V
R1
???
U2A
1
2
74HC04
U1A
1
U2B
2
3
4
74HC05
U2C
5
CMPE 118 MECHATRONICS
6
CMPE 118 MECHATRONICS
74HC04
CMPE 118 MECHATRONICS
74HC04
CMPE 118 MECHATRONICS
Absolute Maximum Ratings
Not so Useful
Quite Useful
CMPE 118 MECHATRONICS
Absolute Maximum Ratings
CMPE 118 MECHATRONICS
HIGH
Logic Levels
and
Noise Margins
VOH
High-State
DC Noise Margin
VIH
ABNORMAL
VIL
Low-State
DC Noise Margin
VOL
LOW
time
For TTL
CMPE 118 MECHATRONICS
VOL=0.4V
VIL=0.8V
VIH=2.0V
VOH=2.4V
For CMOS
VOL=0.5V
VIL=1.5V
VIH=3.5V
VOH=4.5V
@Vcc=5V
What about Slowly Changing Inputs?
CMPE 118 MECHATRONICS
How do you get Hysterisis ?
1) Schmitt Trigger inputs
5V
2) Comparator with Hysterisis
Vin
LM339
R2
CMPE 118 MECHATRONICS
Rpullup
R1
R3
Vout
CMPE 118 MECHATRONICS
74HC14
CMPE 118 MECHATRONICS
Power Outputs
CMPE 118 MECHATRONICS
The Darlington
CMPE 118 MECHATRONICS
DS3658
CMPE 118 MECHATRONICS
DS3658
CMPE 118 MECHATRONICS
CMPE 118 MECHATRONICS
ULN2003A
(1 of 7 per package)
CMPE 118 MECHATRONICS
ULN2003A Specifications
CMPE 118 MECHATRONICS
Not all 7 at once !
CMPE 118 MECHATRONICS