IKA labworldsoft - Manual (Page 63)

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TTL ( 7 ransistor- 7 ransistor- / ogic) levels define the voltage values for distinguishing a logic level 0
from a logic level 1.
The voltage range of the TTL logic is from 0 - 5V (corresponding to a numerical value of 0 - 5 in
ODEZRUOGVRIW ) while values from 0 - 0.8V correspond to the logic level 0, and values from 2 - 5V
correspond to the logical level 1. The range of 0.8 - 2V is the hysteresis between the levels (if a
signal is recognized as Low, the value must rise to above 2 in order to be recognized as High; if
High is recognized, the value must drop to below 0.8 in order to be recognized as Low).
As a rule, where TTL output or input levels within ODEZRUOGVRIW are concerned, 1XPHULFDO
9DOXHV of 0 or 5 are meant.