Digital Logic Fundamentals Unit 4 – Open Collector and Other TTL Gates
Shown are several combinations of logic gates and the effects of a NOT operation.
NEW TERMS AND WORDS
Low Power Schottky (LS) - a type of logic family that uses high speed/low voltage drop diodes
to improve gate performance.
rise times - the period of time required for a signal to move from its 10% point to its 90% point.
Also called the low to high transition time.
fall times. - the period of time required for a signal to move from its 90% point to its 10% point.
Also called the high to low transistion time.
Schmitt-trigger - a type of gate that uses hysteresis to determine threshold points.
VIH - minimum voltage for the input of a standard gate to be logic 1.
VIL - maximum voltage for the input of a standard gate to be logic 0.
buffer - a logic gate with one input and one output, and the output logic state equals the input
logic state.
inverter - a logic gate with one input and one output, and the output logic state is the
complement of the input.
VT+ - the positive-going threshold voltage of a Schmitt gate.
VT- - the negative-going threshold voltage of a Schmitt gate.
hysteresis - a type of positive feedback used to improve the response time of a gate driven by
analog waveforms.
NOT - type of logic circuit used to generate a complement.
OR-TIE - a circuit function that allows more than one gate output to control one circuit point.
transfer characteristic - the relationship between the output and input voltage levels of a logic
gate.