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In digital circuits, a logic level is one of a finite number of states that a digital signal can inhabit. Logic levels are usually represented by the voltage difference between the signal and ground, although other standards exist. The range of voltage levels that represent each state depends on the logic family being used.
Differential TTL is a type of binary electrical signaling based on the transistor-transistor logic (TTL) concept. It enables electronic systems to be relatively immune to noise. [ 1 ] RS-422 and RS-485 outputs can be implemented as differential TTL.
A five level PAM digital signal. In digital electronics, a digital signal is a pulse amplitude modulated signal, i.e. a sequence of fixed-width electrical pulses or light pulses, each occupying one of a discrete number of levels of amplitude. [6] [7] A special case is a logic signal or a binary signal, which varies between a low and a high ...
LVDS is a differential signaling system, meaning that it transmits information as the difference between the voltages on a pair of wires; the two wire voltages are compared at the receiver. In a typical implementation, the transmitter injects a constant current of 3.5 mA into the wires, with the direction of current determining the digital ...
(TTL has the input high level above 2.0 V and the input low level below 0.8 V, so a TTL high-level signal could be in the forbidden middle range for 5 V CMOS.) The 74H family is the same basic design as the 7400 family with resistor values reduced.
Because the voltage levels are higher than logic levels typically used by integrated circuits, special intervening driver circuits are required to translate logic levels. These also protect the device's internal circuitry from short circuits or transients that may appear on the RS-232 interface, and provide sufficient current to comply with the ...
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Transistor–transistor logic (TTL) is a logic family built from bipolar junction transistors.Its name signifies that transistors perform both the logic function (the first "transistor") and the amplifying function (the second "transistor"), as opposed to earlier resistor–transistor logic (RTL) and diode–transistor logic (DTL).