If any of the logic gates becomes logic low transistor conducting , the combined output will be low. Parts for military and aerospace applications were packaged in flatpacks , a form of surface-mount package, with leads suitable for welding or soldering to printed circuit boards. These pulses can couple in unexpected ways between multiple integrated circuit packages, resulting in reduced noise margin and lower performance. 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. TTL integrated circuits ICs were widely used in applications such as computers , industrial controls, test equipment and instrumentation, consumer electronics, and synthesizers.

Uploader: Gardar
Date Added: 5 May 2012
File Size: 17.14 Mb
Operating Systems: Windows NT/2000/XP/2003/2003/7/8/10 MacOS 10/X
Downloads: 76948
Price: Free* [*Free Regsitration Required]

Standard TTL circuits operate with a 5- volt power supply.

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

That is, current flows out of this input and into the zero low voltage source. Its name signifies that transistors perform both the logic function the first “transistor” and the amplifying function the second “transistor” ; it is the same naming convention used in resistor—transistor logic RTL and diode—transistor logic DTL. From Wikipedia, the free encyclopedia.

tp It also limits the output current in the case of output logical “1” and short connection to the ground. Views Read Edit View history.

Typically, TTL chips integrate no more than a few hundred ttll each. Retrieved 16 April After their introduction in integrated circuit form in by SylvaniaTTL integrated circuits were manufactured by several semiconductor companies.


By using this site, you agree to the Terms of Use and Privacy Policy. TTL inputs source 1. The output can be erratic when the input is in this range.

So, as far as I understand, the difference is only internal, whether our ICs operate at 5V or 3. Digital Logic Gates Part-V.

Transistor–transistor logic – Wikipedia

The main advantage of TTL with a “totem-pole” output ot is the low output resistance at output logical “1”. During the transition the input transistor is briefly in its active region; so it draws a large current away from the base of the output transistor and thus quickly discharges its base. Special quality levels and high-reliability parts are available for military and aerospace applications.

This drawback is usually overcome by t the outputs with special line-driver devices where signals need to be sent through cables. Most computers used TTL-compatible ” glue logic ” between larger chips well into the s. By clicking “Post Your Answer”, you acknowledge that you have read our updated terms trl serviceprivacy policy and cookie policyand that your continued use of the website is subject to these policies.

Email Required, but never shown. 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. 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. At their maximum operating frequency they may use more power than equivalent bipolar TTL devices.

It limits the number of inputs that can be connected the fanout. A common variation omits the collector resistor of the output transistor, making an open-collector output. The most recently introduced family 74Fxx is still sold today [ when? An input logical zero.


The main disadvantage of TTL with a simple output stage is the relatively high output resistance at output logical “1” that is completely determined by the output collector resistor. If one input voltage becomes zero, the corresponding base—emitter junction of the multiple-emitter transistor is in parallel with these two junctions.

When V 2 is “off”, V 4 is “off” as well and V 3 operates in active region as a voltage follower producing high output voltage logical “1”.

Transistor–transistor logic

Within usefully broad limits, logic gates can be treated as ideal Boolean devices without concern tgl electrical limitations. The driving stage must absorb up to 1. To solve the problem with the high output resistance of the simple output stage the second schematic adds to this a “totem-pole” ” push—pull ” output.

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.

TTL also became important because its low cost made digital techniques economically practical for tasks previously done by analog methods.