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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These demultiplexers are ideally suited for implementing high-performance memory decoders. Home Questions Tags Users Unanswered. 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 7154 of essentially multiplying you selecting lines by a 4 times.
Will someone please explain the purpose of inverting the outputs 0 through 15 as well as the use the NAND gates here? This carried through to the input current requirements: And that’s what is going on with the 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.
Email Required, but never shown. Sign up using Email and Password. Email Required, but never shown. This chip is often used in demultiplexing applications, dataasheet as digital clocks, LED matrices, and other graphical outputs.
I have a doubt in the demultiplexer section. Please consider upvoting those questions datasheeet found useful like this one datasueet clicking the arrow pointing up near the answer vote count which is in turn above the checkbox you clicked to accept this question. 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.
And why are there 2 of them, you ask?
Datasheet, PDF – Alldatasheet
According to the internal logic dqtasheet 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. Why is the output in the truth table inverted in a ic used as a demux? So is it possible that both enables are hooked dqtasheet a 2-input OR gate; this is just making use of the extra pins to make 24?
So theory will cover only the theory which explains the basic functionality of the working of a demultiplexor. But when we try to implement a demultiplexer using dtasheet TTLthis is the truth table that is given in the book:.
The demultiplexing function is performed by using the 4 input lines to address the output line, passing data from one of dataheet strobe inputs with the other strobe input low. However, due to the internal structure of theonly one output can be enabled at a time. That is, for an input ofthe 0 output is selected, and it is driven low.
You can upvote more than one answer. If you have some experience using BJTs you will know that NPN transistors are best used to pull a signal to 0V common datadheet, with the output connected to the collector and quite weak at pulling a signal high. If you wanted to generate a 1 of demultiplexer, you could use 16 s looking at the 4 least significant bits, ix a single would look at the 4 most significant bits, with one ouput going to each of the other 16 s.
This all has to do with the actual ic design. Why are the outputs inverted?
High speed signals were usually active low, for much the same reason. Download the datasheet below for a more comprehensive summary.
As for the NAND gates, there is a function being implemented in which the gates are there to realize it.
(PDF) 74154 Datasheet download
Many TTL parts and older memory chips have active low enable dataxheet, so the active low outputs of this part can be connected directly to those inputs.
If you want to know exactly what is going on then draw out the truth table, but it is unlikely datasheey function will make much sense to you. Sign up using Facebook. But when we try to implement a demultiplexer using a TTLthis is the truth table that is given in the book: The person who took time to answer the question will appreciate that.
I am a new user so I didn’t know I had that power. Common collector, with the signal connected to the emitter, which remains at 0.
Post as a guest Name. I understand how it works.