In a previous article, we learned about the logic gates, often referred to as the logical "NOT" gate. We have learned that the exit status of these "NOT" login doors is the opposite of the input signal. As we understand from this, when the entrance of the NOT gates is "high", the exit status will not be "high". When the input signal is "low", the output status will not be low ". However, in some cases we may need to insulate the digital doors from each other, as well as reverse the input signal, or we need to load or switch more normally. One of the biggest examples of this will be the relay. The log doors that allow us to do this are called digital buffers. Then let's find out the truth of this logic door. You can also make digital bumper doors by connecting the two "NOT" doors, as shown below. The first "reverses" the input signal, and the second reverts to its original level, applying another inversion to the input. At this point, you can question why we need these circuits, but in fact, the more experience you have, the easier it will be to use these doors. One of the things you should know here is that these special doors are preferred to isolate the logistics doors from each other or in situations such as digital amplification.
In addition to the standard digital buffer seen above, there is another type of digital buffer circuit that can be "electronically" disconnected from the output circuit when its output is required. These circuits are known as 3-state buffer circuits. A three-state buffer can be considered an input-controlled switch with an output that can be electronically "on" or "off" with external signal input. You can think of it as a control circuit. At this point, buffers with 3 states are divided into four varieties. At this point, the distinction between these 4 circuits has a really important place. These 3-state buffer circuits are available in order:
- Active Low Buffer (Active "HIGH" Tri-state Buffer)
- Active Reverse Low Buffer (Active "LOW" Inverting Tri-state Buffer)
- Active High Buffer
- Active Reverse High Buffer (Active "HIGH" Inverting Tri-state Buffer)
Then let's see the accuracy of all four circuits.
Active High Buffer
Active Reverse High Buffer (Active "HIGH" Inverting Tri-state Buffer)
Active Low Buffer (Active "HIGH" Tri-state Buffer)
Active Reverse Low Buffer (Active "LOW" Inverting Tri-state Buffer)
Then let's finally look at the digital bumper doors and 3-state buffer doors used today.
TTL Logistics or NOT Door Integrated Examples
- 74LS17 Six-Way Bumper Door
- 74LS244 Eight Bumper Door
CMOS Logistics or NOT Door Integrated Examples
- CD4503 Six-State Buffer
- HEF40244 Eight 3-State Bumper Door