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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I am a new user so I didn’t know I had that power. 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. The active-low output is just how the design for that specific decoder was carried out – there is also active-high varieties.
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4 Line to 16 Line Demultiplexer / Decoder
Will someone please explain the purpose of inverting the outputs 0 through 15 as well as the 7454 the NAND gates here? This allows more flexibility in 744154 logic functions available. 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.
Sign up using Facebook. 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.
Since the ouputs are active low, NAND gates do the job. However, due to the internal structure of thedafasheet one output can be enabled at a time. These demultiplexers are ideally suited for implementing high-performance memory decoders. And why are there 2 of them, you ask? The active-low enable inputs allow cascading of demultiplexers over many bits.
74154 Datasheet PDF
All inputs are buffered and input clamping diodes are provided to minimize transmission-line effects and thereby simplify system design. First, the inversion of the outputs simply means that the output is active low.
The LED can be chosen at random by the status of the 4 line selector inputs. Each of the 16 outputs can be connected through a resistor and then through an LED to serve as a simple 16 LED controller. My first question is more important You can upvote more than one answer.
For example, if the datashfet 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. Understand, this is a typical example of application, not it’s sole purpose.
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. 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. All the other ouputs stay high. This chip is often used in demultiplexing applications, such as digital clocks, LED matrices, and other graphical outputs.
As for the NAND gates, there is a function being implemented in which the gates are there to realize it.