Performance Silicon? The HC decodes a three? This device features three Chip Select inputs, two active? The demultiplexing function is accomplished by using the Address inputs to select the desired device output; one of the Chip Selects is used as a data input while the other Chip Selects are held in their active states. Operating Voltage Range: 2. Low Input Current: 1.
|Published (Last):||1 December 2011|
|PDF File Size:||5.2 Mb|
|ePub File Size:||10.39 Mb|
|Price:||Free* [*Free Regsitration Required]|
Overview of 74LS Decoder As mentioned earlier the chip is specifically designed to be used in high-performance memory-decoding or data-routing applications which require very short propagation delay times. The memory unit data exchange rate determines the performance of any application and the delays of any kind are not tolerable there. In such applications using 74LS line decoder is ideal because the delay times of this device are less than the typical access time of the memory.
This means that the effective system delay introduced by the decoder is negligible to affect the performance. How to use 74LS Decoder For understanding the working of device let us construct a simple application circuit with a few external components as shown below.
About circuit: Here the outputs are connected to LED to show which output pin goes LOW and do remember the outputs of the device are inverted. The three buttons here represent three input lines for the device. For understanding the working let us consider the truth table of the device. After connecting the enable pins as shown in circuit diagram you can use the input line to get the output.
This way we can realize all the truth table by toggling the three buttons B1, B2 and B3 Three inputs A0, A1 and A2 and with that we have three input to eight output decoder.
MM74HC138: 3 to 8 Line Decoder
Working of 74138 decoder IC