74154 DATASHEET PDF
The NTE is a monolithic 4-line-toline decoder in a Lead DIP type The NTE is fully compatible for use with most other TTL and DTL circuits. MOS technology. A binary code applied to the four inputs (A to D) provides a low level at the selected one of sixteen outputs excluding the other fifteen outputs. SNN .. of significant portions of TI information in TI data books or data sheets is permissible only if reproduction is without alteration.
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That is, if the outputs were active high, OR gates would perform the synthesis desired. This chip is often used in demultiplexing applications, such as digital clocks, LED matrices, and other graphical outputs. Each of the 16 outputs can be connected through a resistor and then through an LED to serve as a simple 16 Datasjeet controller.
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. These demultiplexers are ideally suited for implementing high-performance memory decoders.
For example, if datsaheet 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.
Download the datasheet below for a more comprehensive summary. Home Questions Tags Users Unanswered. Sign up using Facebook.
You can upvote more than one answer. That is, for an input ofthe 0 output is selected, and it is driven low.
74154 Datasheet PDF
And why are there 2 of them, you datasueet All the other ouputs stay high. The demultiplexing function is performed by using the 4 input lines to address the output line, passing data from one of the strobe inputs with the other strobe input low. Post as a guest Name.
So is it possible that both enables are hooked to a 2-input OR gate; this is just making use of the extra pins to make 24? This allows more flexibility in the logic functions available. The active-low enable xatasheet allow cascading of demultiplexers over many bits. Email Required, but never shown. Sign up or dztasheet in Sign up using Google. Will someone please explain the purpose of inverting the outputs 0 through 15 as well as the use the NAND gates here? Please consider upvoting those questions you found useful daatasheet this one by clicking the arrow pointing up near the answer vote count which is in turn above the checkbox you clicked to accept this question.
Understand, this is a typical example of application, not it’s sole purpose. Since the ouputs are active low, NAND gates do the job. The active-low output is just how the satasheet for that specific decoder was carried out – there is also datashete varieties. My first question is more important WhatRoughBeast 49k 2 28 Many TTL parts and older memory chips have active low enable inputs, so the active low outputs of this part can be connected directly to those inputs.
Rather than providing only a single enable, both pins are used. 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 look at the 4 most significant bits, with one ouput going to each of the other 16 s. First, the inversion of the outputs simply means that the output is active low. The person who took time to answer the question will appreciate that.
However, due to the internal structure of theonly one output can datashwet enabled at a time. As for the NAND gates, there is a function being implemented in which the gates datasgeet there to realize it.
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.
4 to 16 decoder logic diagram – Electrical Engineering Stack Exchange
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. Sign up using Email and Password. When either strobe input is high, all outputs are high. 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.