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Real logic gatesMeasuring voltage limits
ElectronicsLogic Gates: Measuring Voltage Limits
Terry Sturtevant
Wilfrid Laurier University
November 20, 2014
Terry Sturtevant Electronics Logic Gates: Measuring Voltage Limits

Real logic gatesMeasuring voltage limits Reading Data sheets
Input voltages will not always be at ideal values
a range of input values must be considered highanother range of input values must be considered low.Similarly output voltages will not always be at ideal valuesa range of output voltages should be considered as highanother range of output voltages should be considered low.
Terry Sturtevant Electronics Logic Gates: Measuring Voltage Limits

Real logic gatesMeasuring voltage limits Reading Data sheets
Input voltages will not always be at ideal valuesa range of input values must be considered high
another range of input values must be considered low.Similarly output voltages will not always be at ideal valuesa range of output voltages should be considered as highanother range of output voltages should be considered low.
Terry Sturtevant Electronics Logic Gates: Measuring Voltage Limits

Real logic gatesMeasuring voltage limits Reading Data sheets
Input voltages will not always be at ideal valuesa range of input values must be considered highanother range of input values must be considered low.
Similarly output voltages will not always be at ideal valuesa range of output voltages should be considered as highanother range of output voltages should be considered low.
Terry Sturtevant Electronics Logic Gates: Measuring Voltage Limits

Real logic gatesMeasuring voltage limits Reading Data sheets
Input voltages will not always be at ideal valuesa range of input values must be considered highanother range of input values must be considered low.Similarly output voltages will not always be at ideal values
a range of output voltages should be considered as highanother range of output voltages should be considered low.
Terry Sturtevant Electronics Logic Gates: Measuring Voltage Limits

Real logic gatesMeasuring voltage limits Reading Data sheets
Input voltages will not always be at ideal valuesa range of input values must be considered highanother range of input values must be considered low.Similarly output voltages will not always be at ideal valuesa range of output voltages should be considered as high
another range of output voltages should be considered low.
Terry Sturtevant Electronics Logic Gates: Measuring Voltage Limits

Real logic gatesMeasuring voltage limits Reading Data sheets
Input voltages will not always be at ideal valuesa range of input values must be considered highanother range of input values must be considered low.Similarly output voltages will not always be at ideal valuesa range of output voltages should be considered as highanother range of output voltages should be considered low.
Terry Sturtevant Electronics Logic Gates: Measuring Voltage Limits

Real logic gatesMeasuring voltage limits Reading Data sheets
VIHmin
the minimum input voltage which will be accepted as a logic1.VILmaxthe maximum input voltage which will be accepted as a logic0.VOHminthe minimum output voltage representing a logic 1 state.VOLmaxthe maximum output voltage representing a logic 0 state.
Terry Sturtevant Electronics Logic Gates: Measuring Voltage Limits

Real logic gatesMeasuring voltage limits Reading Data sheets
VIHminthe minimum input voltage which will be accepted as a logic1.
VILmaxthe maximum input voltage which will be accepted as a logic0.VOHminthe minimum output voltage representing a logic 1 state.VOLmaxthe maximum output voltage representing a logic 0 state.
Terry Sturtevant Electronics Logic Gates: Measuring Voltage Limits

Real logic gatesMeasuring voltage limits Reading Data sheets
VIHminthe minimum input voltage which will be accepted as a logic1.VILmax
the maximum input voltage which will be accepted as a logic0.VOHminthe minimum output voltage representing a logic 1 state.VOLmaxthe maximum output voltage representing a logic 0 state.
Terry Sturtevant Electronics Logic Gates: Measuring Voltage Limits

Real logic gatesMeasuring voltage limits Reading Data sheets
VIHminthe minimum input voltage which will be accepted as a logic1.VILmaxthe maximum input voltage which will be accepted as a logic0.
VOHminthe minimum output voltage representing a logic 1 state.VOLmaxthe maximum output voltage representing a logic 0 state.
Terry Sturtevant Electronics Logic Gates: Measuring Voltage Limits

Real logic gatesMeasuring voltage limits Reading Data sheets
VIHminthe minimum input voltage which will be accepted as a logic1.VILmaxthe maximum input voltage which will be accepted as a logic0.VOHmin
the minimum output voltage representing a logic 1 state.VOLmaxthe maximum output voltage representing a logic 0 state.
Terry Sturtevant Electronics Logic Gates: Measuring Voltage Limits

Real logic gatesMeasuring voltage limits Reading Data sheets
VIHminthe minimum input voltage which will be accepted as a logic1.VILmaxthe maximum input voltage which will be accepted as a logic0.VOHminthe minimum output voltage representing a logic 1 state.
VOLmaxthe maximum output voltage representing a logic 0 state.
Terry Sturtevant Electronics Logic Gates: Measuring Voltage Limits

Real logic gatesMeasuring voltage limits Reading Data sheets
VIHminthe minimum input voltage which will be accepted as a logic1.VILmaxthe maximum input voltage which will be accepted as a logic0.VOHminthe minimum output voltage representing a logic 1 state.VOLmax
the maximum output voltage representing a logic 0 state.
Terry Sturtevant Electronics Logic Gates: Measuring Voltage Limits

Real logic gatesMeasuring voltage limits Reading Data sheets
VIHminthe minimum input voltage which will be accepted as a logic1.VILmaxthe maximum input voltage which will be accepted as a logic0.VOHminthe minimum output voltage representing a logic 1 state.VOLmaxthe maximum output voltage representing a logic 0 state.
Terry Sturtevant Electronics Logic Gates: Measuring Voltage Limits

Real logic gatesMeasuring voltage limits Reading Data sheets
Reading Data sheets
The actual limits on voltage, current, timing, etc. will begiven in manufacturer’s data sheets.Different manufacturers arrange their data sheets differently,and use different names.
Terry Sturtevant Electronics Logic Gates: Measuring Voltage Limits

Real logic gatesMeasuring voltage limits Reading Data sheets
Reading Data sheets
The actual limits on voltage, current, timing, etc. will begiven in manufacturer’s data sheets.
Different manufacturers arrange their data sheets differently,and use different names.
Terry Sturtevant Electronics Logic Gates: Measuring Voltage Limits

Real logic gatesMeasuring voltage limits Reading Data sheets
Reading Data sheets
The actual limits on voltage, current, timing, etc. will begiven in manufacturer’s data sheets.Different manufacturers arrange their data sheets differently,and use different names.
Terry Sturtevant Electronics Logic Gates: Measuring Voltage Limits

Real logic gatesMeasuring voltage limits Reading Data sheets
Supply voltage Designations
The supply voltages for various families have names which arebased on the type of transistors used in their construction.For instance, TTL gates are made with bipolar transistors,which have a collector and an emitter,the supply voltages are VCC and GROUND is occasionallygiven as VEE.On the other hand, CMOS gates are built with field–effecttransistors which have a drain and a source,the supply voltages are VDD and VSS.
Terry Sturtevant Electronics Logic Gates: Measuring Voltage Limits

Real logic gatesMeasuring voltage limits Reading Data sheets
Supply voltage Designations
The supply voltages for various families have names which arebased on the type of transistors used in their construction.
For instance, TTL gates are made with bipolar transistors,which have a collector and an emitter,the supply voltages are VCC and GROUND is occasionallygiven as VEE.On the other hand, CMOS gates are built with field–effecttransistors which have a drain and a source,the supply voltages are VDD and VSS.
Terry Sturtevant Electronics Logic Gates: Measuring Voltage Limits

Real logic gatesMeasuring voltage limits Reading Data sheets
Supply voltage Designations
The supply voltages for various families have names which arebased on the type of transistors used in their construction.For instance, TTL gates are made with bipolar transistors,which have a collector and an emitter,the supply voltages are VCC and GROUND is occasionallygiven as VEE.
On the other hand, CMOS gates are built with field–effecttransistors which have a drain and a source,the supply voltages are VDD and VSS.
Terry Sturtevant Electronics Logic Gates: Measuring Voltage Limits

Real logic gatesMeasuring voltage limits Reading Data sheets
Supply voltage Designations
The supply voltages for various families have names which arebased on the type of transistors used in their construction.For instance, TTL gates are made with bipolar transistors,which have a collector and an emitter,the supply voltages are VCC and GROUND is occasionallygiven as VEE.On the other hand, CMOS gates are built with field–effecttransistors which have a drain and a source,the supply voltages are VDD and VSS.
Terry Sturtevant Electronics Logic Gates: Measuring Voltage Limits

Real logic gatesMeasuring voltage limits
Measuring voltage limits
In order to measure the voltage limits, you can connect up thecircuit as in the following figure.
Terry Sturtevant Electronics Logic Gates: Measuring Voltage Limits

Real logic gatesMeasuring voltage limits
Measuring voltage limits
In order to measure the voltage limits, you can connect up thecircuit as in the following figure.
Terry Sturtevant Electronics Logic Gates: Measuring Voltage Limits

Real logic gatesMeasuring voltage limits
Vcc
Vin
1 2
GND
Terry Sturtevant Electronics Logic Gates: Measuring Voltage Limits

Real logic gatesMeasuring voltage limits
Using a sine wave input with the oscilloscope operating in the X–Ymode, a trace similar to the one shown in the following figureshould be obtained.
(The output shown is for an LSTTL inverting gate.)
Terry Sturtevant Electronics Logic Gates: Measuring Voltage Limits

Real logic gatesMeasuring voltage limits
Using a sine wave input with the oscilloscope operating in the X–Ymode, a trace similar to the one shown in the following figureshould be obtained.(The output shown is for an LSTTL inverting gate.)
Terry Sturtevant Electronics Logic Gates: Measuring Voltage Limits

Real logic gatesMeasuring voltage limits
Terry Sturtevant Electronics Logic Gates: Measuring Voltage Limits

Real logic gatesMeasuring voltage limits
Vin
Terry Sturtevant Electronics Logic Gates: Measuring Voltage Limits

Real logic gatesMeasuring voltage limits
Vin
Vout
Terry Sturtevant Electronics Logic Gates: Measuring Voltage Limits

Real logic gatesMeasuring voltage limits
Vin
Vout
logic “0” input0.8
Terry Sturtevant Electronics Logic Gates: Measuring Voltage Limits

Real logic gatesMeasuring voltage limits
Vin
Vout
logic “0” input0.8
����VOHmin
Terry Sturtevant Electronics Logic Gates: Measuring Voltage Limits

Real logic gatesMeasuring voltage limits
Vin
Vout
logic “1” input2.0
Terry Sturtevant Electronics Logic Gates: Measuring Voltage Limits

Real logic gatesMeasuring voltage limits
Vin
Vout
logic “1” input2.0
����VOLmax
Terry Sturtevant Electronics Logic Gates: Measuring Voltage Limits

Real logic gatesMeasuring voltage limits
Vin
Vout
logic “0”output
0.5
Terry Sturtevant Electronics Logic Gates: Measuring Voltage Limits

Real logic gatesMeasuring voltage limits
Vin
Vout
logic “0”output
0.5 ����
VIHmin
Terry Sturtevant Electronics Logic Gates: Measuring Voltage Limits

Real logic gatesMeasuring voltage limits
Vin
Vout
logic “1”output
2.7
Terry Sturtevant Electronics Logic Gates: Measuring Voltage Limits

Real logic gatesMeasuring voltage limits
Vin
Vout
logic “1”output
2.7 ����
VILmax
Terry Sturtevant Electronics Logic Gates: Measuring Voltage Limits

Real logic gatesMeasuring voltage limits
This is called the transfer characteristic of the gate.
Note that the input voltage, Vin, is on the X axis and the outputvoltage, Vout, on the Y axis.
Terry Sturtevant Electronics Logic Gates: Measuring Voltage Limits

Real logic gatesMeasuring voltage limits
This is called the transfer characteristic of the gate.Note that the input voltage, Vin, is on the X axis and the outputvoltage, Vout, on the Y axis.
Terry Sturtevant Electronics Logic Gates: Measuring Voltage Limits

Real logic gatesMeasuring voltage limits
Vin
Vout
CMOS will look slightly different.
Terry Sturtevant Electronics Logic Gates: Measuring Voltage Limits

Real logic gatesMeasuring voltage limits
Vin
Vout
CMOS will look slightly different.
Terry Sturtevant Electronics Logic Gates: Measuring Voltage Limits

Real logic gatesMeasuring voltage limits
Measuring Output Voltage Limits
The output voltage produced by an input voltage of thespecified value of VILmax would be the measured value ofVOHmin .The output voltage is produced by an input voltage of thespecified value of VIHmin would be the measured value ofVOLmax .
Terry Sturtevant Electronics Logic Gates: Measuring Voltage Limits

Real logic gatesMeasuring voltage limits
Measuring Output Voltage Limits
The output voltage produced by an input voltage of thespecified value of VILmax would be the measured value ofVOHmin .
The output voltage is produced by an input voltage of thespecified value of VIHmin would be the measured value ofVOLmax .
Terry Sturtevant Electronics Logic Gates: Measuring Voltage Limits

Real logic gatesMeasuring voltage limits
Measuring Output Voltage Limits
The output voltage produced by an input voltage of thespecified value of VILmax would be the measured value ofVOHmin .The output voltage is produced by an input voltage of thespecified value of VIHmin would be the measured value ofVOLmax .
Terry Sturtevant Electronics Logic Gates: Measuring Voltage Limits

Real logic gatesMeasuring voltage limits
Measuring Output Voltage Limits
The output voltage produced by an input voltage of thespecified value of VILmax would be the measured value ofVOHmin .The output voltage is produced by an input voltage of thespecified value of VIHmin would be the measured value ofVOLmax .
Terry Sturtevant Electronics Logic Gates: Measuring Voltage Limits
Real logic gatesReading Data sheets
Measuring voltage limits