Is this an asynchronous down counter?

  • Thread starter stobbz
  • Start date
  • #1
13
0
[PLAIN]http://img30.imageshack.us/img30/3306/counterty.jpg [Broken]

Is this an asynchronous down counter, or is it nonsense? (Assuming all J and K inputs are connected high)

Trivial question, I know :-)
 
Last edited by a moderator:

Answers and Replies

  • #2
vk6kro
Science Advisor
4,081
40
Yes, it is an asynchronous binary counter that counts downwards.

However, it would have problems with propagation delays and these would cause the outputs to be wrong for a short period after some of the clock pulses.

I put the circuit into a simulator that includes propagation delays and it showed up a large number of glitches in the output.

So, you get the following (with glitch outputs shown in brackets):

0
(1)
(3)
(7)
F
E
(F)
D
C
(D)
(F)
B
A
(B)
9
8
(9)
(B)
(F)
7
6
(7)
5
4
(5)
(7)
3
2
(3)
1
0

So, it would be OK just as a divider but not for any serious counter application.
 

Related Threads on Is this an asynchronous down counter?

  • Last Post
Replies
3
Views
5K
  • Last Post
Replies
1
Views
1K
Replies
2
Views
1K
  • Last Post
Replies
1
Views
5K
  • Last Post
Replies
13
Views
10K
  • Last Post
Replies
3
Views
3K
  • Last Post
Replies
12
Views
3K
Replies
2
Views
1K
Replies
1
Views
735
Top