IC 74154 DATASHEET PDF

Integrated Circuit. Transistor Transistor Logic (TTL). 4−Line−to−16−Line Decoder /Demultiplexer. 24−Lead DIP Type Package. Description: The NTE is a. 1) CPD is defined as the value of the IC’s internal equivalent capacitance which is calculated from the operating current consumption without load. (Refer to Test . datasheet, circuit, data sheet: NSC – 4-Line to Line for Electronic Components and Semiconductors, integrated circuits, diodes, triacs.

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Sign up or log in Sign up using Google. These demultiplexers are ideally suited for implementing high-performance memory decoders. Since the ouputs are active low, NAND gates do the job. So dqtasheet are inverted a explained in the theory. Sign up using Facebook.

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Datasheet(PDF) – National Semiconductor (TI)

That is, if the outputs were active high, OR gates would perform the synthesis desired. I understand how it works. If you have some experience datasheeet BJTs you will know that NPN transistors are best used to pull a signal to 0V common emitter, with the output connected to the collector and quite weak at pulling a signal high.

The active-low output is just how the design for that specific decoder was carried out – there is also active-high varieties. For example, if the target application requires 16 7-segment LED displays, but your microcontroller only has 4 lines to select which display is active, this chip 74LS would provide a very effective method of essentially multiplying you selecting lines by a 4 times.

Sign up or log in Sign up using Google. The actual implementation of the chosen ic has active low outputs. High speed signals were usually active low, for much the same reason.

National Semiconductor

By using our site, you acknowledge that you have read and understand our Cookie PolicyPrivacy Policy datashfet, and our Terms of Service. So you can use a 47 kilohm resistor to pull up drops 1. This is the image of a 1 to 16 demux. I am a new user so I didn’t know I had that power. Sign up using Facebook. Why is the output in the truth table inverted in a ic used as a demux?

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And that’s what is going on with the That is, for an input ofthe 0 output is selected, and it is driven low.

All inputs are buffered and input clamping diodes are provided to minimize transmission-line effects and thereby simplify system design. It is counterintuitive yes, but it is a well-established convention that the sort of devices that this part will be controlling will have active-low enable inputs.

Home Questions Tags Users Unanswered. The person who took time to answer the question will appreciate that. You can upvote more than one answer. There are probably two enable inputs because otherwise there would be two unused pins on the 24 pin package I don’t recall seeing 22 pin DIP packages. Sign up using Email and Password. Please consider upvoting those questions you found useful like this one by clicking the arrow daasheet up near the answer vote count which is in turn above the checkbox datasheeg clicked to accept this question.

This allows more flexibility in the logic functions available.

741554 WhatRoughBeast 49k 2 28 Inputs were pulled high by default, and only pulled low when necessary, to save power. But when we try to implement datsaheet demultiplexer using a TTLthis is the truth table that is given in the book: The LED can be chosen at random by the status of the 4 line selector inputs.

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4 Line to 16 Line Demultiplexer / Decoder

But when we try to implement a demultiplexer using a TTLthis is the truth table that is given in datasbeet book:. Each of the 16 outputs can be connected through a resistor and then through an LED to serve as a simple 16 LED controller. Is the hardware implementation circuit different than the one explained in theory? Rather than providing only a single enable, both pins are used. Download dataaheet datasheet below for a more comprehensive summary. If you want to know exactly what is going on then draw out the truth table, but it is unlikely their function will make much sense to you.

So TTL circuitry adopted asymmetric logic levels, where ‘0’ was guaranteed to be below 0. According to the internal logic diagram on the datasheet, the G inputs are connected to a two-input AND gate with inverting inputs, whose output feeds one input of all the NAND gates that produce the outputs.

Each or these 4-line-toline decoders utilizes TTL circuitry to decode four binary-coded inputs into one of sixteen mutually exclusive outputs when both the strobe inputs, G1 and G2, are low. If you wanted to generate a 1 of demultiplexer, you could use 16 s looking at the 4 least significant bits, while a single would datsheet at the 4 most significant bits, with one ouput going to each of the other 16 s.

Many TTL parts and older memory chips have active low enable inputs, so datahseet active low outputs of this part can be connected directly to those dstasheet. Post as a guest Name.

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All the other ouputs stay high.