From Wikipedia, the free encyclopedia. Harvard University faculty web page. The term “TTL” is applied to many successive generations of bipolar logic, with gradual improvements in speed and power consumption over about two decades. Webarchive template wayback links All articles with vague or ambiguous time Vague or ambiguous time from September Commons category link is on Wikidata Wikipedia articles with GND identifiers. It should not receive 5V, does it? Post Your Answer Discard By clicking “Post Your Answer”, you acknowledge that you have read our updated terms of service , privacy policy and cookie policy , and that your continued use of the website is subject to these policies. It also limits the output current in the case of output logical “1” and short connection to the ground.

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By using this site, you agree to the Terms of Use and Privacy Policy. The TTL “totem-pole” output structure often has a momentary overlap when both the upper lvytl lower transistors are conducting, resulting in a substantial pulse of current drawn from the power supply.

That is, current flows out of this input and into the zero low voltage source. Due to the output structure of TTL devices, the output impedance is asymmetrical between the high and low state, making them unsuitable for driving transmission lines. The strength of the gate may be increased without proportionally affecting tttl power consumption by removing the pull-up and pull-down resistors from the output stage.

A TTL gate may operate inadvertently as an analog amplifier if the input is connected to a slowly changing input signal that traverses the unspecified region from 0. By using our site, you acknowledge that you have read and understand our Cookie PolicyPrivacy Policyand our Terms of Service.


Transistor–transistor logic

If one input voltage becomes zero, the corresponding base—emitter junction of the multiple-emitter transistor is in parallel with these two junctions. Within usefully broad limits, logic gates can be treated as ideal Boolean devices without concern for electrical limitations.

During the transition the input transistor is briefly in its lvtt, region; so it draws a large current away from the base of the output transistor and thus quickly discharges its base.

These pulses can couple in unexpected ways between multiple integrated circuit packages, ltvtl in reduced noise margin and lower performance. CMOS devices consume power proportional to their switching frequency When all the inputs are held at high voltage, the base—emitter junctions of the multiple-emitter transistor are reverse-biased.

TTL inputs source 1. The main advantage of TTL with a “totem-pole” output stage is the low output resistance at output logical “1”. If such an analog input must be used, there are specialized TTL parts with Schmitt trigger inputs available that will reliably convert the analog input to a digital value, effectively operating as a one bit A to D converter.

Open-collector outputs of some gates have a higher maximum voltage, such as 15V for the[16] useful when driving other than TTL loads.

Solved: OK to put in 5V TTL into a LVTTL devices – Discussion Forums – National Instruments

This is because the transistor is in reverse-active mode. In other projects Wikimedia Commons. To solve the problem with the high output resistance of the tl output stage the tp schematic adds to this a “totem-pole” ” push—pull ” output. Sign up or log in Sign up using Google. But in an integrated circuit, the additional emitters for extra gate inputs add only a small area. The output stage of the most common Lvttll gates is specified to function correctly when driving up to 10 standard input stages a fanout of The resistor R 3 does not increase the output resistance since it is connected in the V 3 collector and its influence is compensated by the negative feedback.


Again there is a current-steering effect: The second series combination has the ttp threshold voltage, so no current flows through it, i. As a result, no current flows through the base of the output transistor, causing it to stop conducting and the output voltage becomes high logical one.

Beam-lead chip dies without packages were made for assembly into larger arrays as hybrid integrated circuits. Home Questions Tags Users Unanswered.

Is an LVTTL output fully compatible to a TTL output? – Electrical Engineering Stack Exchange

Even after Very-large-scale integration integrated circuits made multiple-circuit-board processors obsolete, TTL devices still found extensive use as the glue logic interfacing between more densely integrated components. It is driven by applying the same current steering idea as above.

Archive of web page from University of Connecticut. Post ftl a guest Name.

Inputs both logical ones. Such amplifiers may be useful to convert analog signals to the digital domain but would not ordinarily be used where analog amplification is the primary purpose. Epoxy plastic PDIP packages were often used for commerical temperature range components, while ceramic packages CDIP were used for military temperature range parts.