Test
Parameter 
Unit 
Typical
Description 
Logic High Input
Voltage,
Vih (Logic "1") 
V 
This is the
minimum voltage that an input of a TTL digital IC is guaranteed to
recognize as a Logic "1".
Standard Spec:
2.0 V min. 
Logic Low Input
Voltage,
Vil (Logic "0") 
V 
This is the
maximum voltage that an input of a TTL digital IC is guaranteed to
recognize as a Logic "0".
Standard Spec:
0.8 V max. 
Logic High Output
Voltage,
Voh (Logic "1") 
V 
This is the
minimum voltage that an output of a TTL digital IC is guaranteed to
deliver as a Logic "1".
Standard Spec:
2.4 V min. 
Logic Low
Output
Voltage,
Vol
(Logic "0") 
V 
This is the
maximum voltage that an output of a TTL digital IC is guaranteed to
deliver as a Logic "0".
Standard Spec:
0.4 V max. 
Logic High
Input Current,
Iih

µA 
This is the
minimum amount of current needed by an input of a TTL digital IC to stay
at Logic "1".
Example of an
Actual Spec:
50 µA
min. when Vcc=Max; Vin = 2.7V 
Logic Low Input
Current,
Iil 
mA 
This is the
maximum amount of current
that the input of a TTL digital IC can sink to stay at Logic "0".
Example of an
Actual Spec:
1.6 mA max. when
Vcc=max; Vin = 0.5V 
Output Short
Circuit
Current,
Ios 
mA 
This is the
amount of current that a shortcircuited TTL digital output exhibits or
can handle.
Example of an
Actual Spec:
40 mA min.,
65 mA typ., 100 mA max. when Vcc=max; Vout = 0V 
Supply
Current,
Icc 
mA 
This is the Vcc
supply current exhibited by a TTL IC.
Example of an
Actual Spec:
30 mA min., 50
mA max. when Vcc=max 