![]() ![]() The errors are produced by the FFs inability to keep up with the clock. A high-speed clock can cause the lower stage FFs to change state before the upper stages have reacted to the previous clock pulse. Because the ripple count is asynchronous, it can produce erroneous indications when the clock speed is high. Fig (ii) 4 Bit Synchronous binary counter IC-74190 Pin diagram. Asynchronous means that the events (setting and resetting of FFs) occur one after the other rather than all at once. Fig (i) 4 Bit Synchronous binary counter circuit diagram and waveform. The ripple counter is also called an ASYNCHRONOUS counter. ![]() To display a count of 16 10 or 10000 2, we would need to add another FF. The counter would then start at 0001 2 on clock pulse 17. This will cause FF2 through FF4 to reset, in order, and will extinguish lamps B, C, and D. Clock pulse 16 will cause FF1 to reset and lamp A to go out. At that time the count will be 1111 2 or 15 10. This setting and resetting of the FFs will continue until all the FFs are set and all the lamps are lit. Clock pulse 4 causes FF1 to reset, which causes FF2 to reset, which causes FF3 to set, giving us a count of 0100 2. After three clock pulses, the indicated count is 0011 2. The setting of FF1 does not affect FF2, and lamp B stays lit. Clock pulse 3 causes FF1 to set and lights lamp A. Start by setting up the outputs as shown, then write the logic equation for each input. Notice the inputs to each flip-flop A tabular technique for analysis is illustrated for the counter on the previous slide. The count after two clock pulses is 0010 2, or 2 10. Timing diagram (3-bit syn counter) The next slide shows how to analyze this counter by writing the logic equations for each input. synchronous counter with the help of neat logic diagram, timing diagram and. This negative-going input to FF2 causes it to set and causes B to light. ripple counter, Asynchronous counter-4 bit up/down counter, Asynchronous counter. The negative-going pulse of clock pulse 2 toggles FF1, causing it to reset. This lights lamp A, and we have a count of 0001 2. The negative-going pulse of clock pulse 1 causes FF1 to set. The lamps will all be out, and the count indicated will be 0000 2. Assume that A, B, C, and D are lamps and that all the FFs are reset. Thankfully, the design of a 4-bit binary counter circuit is simple enough that anyone can learn how to build one, allowing people to create their own versions to suit their needs.3-24 Figure 3-23. But we can use the JK flip-flop also with J and K connected permanently to logic 1. A 4-bit binary counter circuit is incredibly useful for a variety of applications, and many businesses and organizations rely on these circuits for a lot of their operations. The logic diagram of a 2-bit ripple up counter is shown in figure. Lastly, these circuits are used in synchronous counters due to their ability to accurately keep track of time. Similarly, sequential logic circuits use 4-bit binary counters to carry out instructions in a predetermined order. They are often used in digital control systems, as they are capable of counting from zero to fifteen and can store a large amount of data that can be accessed quickly. The practical uses of 4-bit binary counter circuits range from timing and sequencing to memory systems. Each gate is responsible for processing one bit of the 4-bit counter, and the outputs of all four gates are combined to form the final four-bit binary output. Let us begin with reset condition of the counter. All the outputs of the counter are written in the following starting with Q0, Q1 and finally Q2. Clock input is the square wave which drives the first flip flop. This means that each gate can receive two different binary inputs and output one binary number. Figure 7: Asynchronous down counter The timing diagram of the ripple down counter is shown in figure 8. While there are various circuit designs that can be used, the most common one involves using four gates, each with two inputs and one output. Figure-1: Asynchronous Counter Circuit and Timing Diagram. We can understand it by following diagram. To understand the logic behind it, think of it as counting up in increments of one: 0, 1, 2, 3, and so on. In asynchronous counter we don’t use universal clock, only first flip flop is driven by main clock and the clock input of rest of the following counters is driven by output of previous flip flops. It counts up each time the clock pulse is pulsed, and then returns to zero when it reaches fifteen. A 4-bit binary counter is a device that can count from zero to fifteen, storing data in a four-bit binary format. To understand why such a circuit is important, let’s start by discussing what a 4-bit binary counter actually is and how it works. But the truth is that these circuits are incredibly useful for many applications, including in digital control systems, sequential logic, and synchronous counters. Why Do We Need a 4-Bit Binary Counter Circuit? The thought of building a 4-bit binary counter circuit might make some people pause - after all, the concept seems a bit complicated. ![]()
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