Understanding the difference between synchronous and asynchronous counters is crucial due to the widespread confusion surrounding counters. In this discussion, we will focus on key points that provide clarity on these counters, such as propagation delay, state change, cost, and circuit diagram differences. By exploring these aspects, you will gain a better understanding of the distinctions between synchronous and asynchronous counters.
| ASYNCHRONOUS COUNTER | SYNCHRONOUS COUNTER |
|---|---|
| 1. State of the device can change at any time in response to changing input. | 1. State of the device changes only at discrete times in response to a clock signal. |
| 2. The logic circuit of this type of counter is simple to design and we feed the output of one flip-flop to the clock of the next flip-flop(clock to LSB). | 2. The circuit diagram for this type of counter becomes difficult as the number of states increases in the counter(as all flip-flops are connected to the same clock, and all are triggered simultaneously). |
| 3. Propagation delay is given as: Tpd=N*(delay of 1 flip-flop) |
3. Propagation delay is given as: Tpd=(Delay of 1 flip-flop)*(delay of 1 gate) |
| 4. Maximum frequency of operation is low because of long propagation delay. | 4. Maximum frequency of operation is high due to shorter propagation delay. |
| 5. As the clock propagates through a number of stages, speed is slow hence high propagation delay as the single clock is given to the whole counter. | 5. As the individual clock is given for every flip-flop, speed is fast. |
| 6. All flip-flops are toggle flip-flops in Asynchronous counters. | 6. Any flip-flop can be used for a synchronous counter. |
| 7. Less cost as simple design. | 7. More cost as complex design. |
| 8. No extra logic gate circuits are required. | 8. Extra logic gates are required based on design. |
9. Circuit diagram:
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9. Circuit diagram:
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