Help with setting up counter

[McDroogie]

I would like to to set up some 4520s CMOS chips and attach them to a seven segment display and make them count or display numbers. The link for the data sheet is posted below. They came in a pack of two and say dual. What does this mean? Can they be used separately or must they be used together in order to make them function?

http://www.nxp.com/documents/data_sheet/HEF4520B.pdf

 

[davenn]

Dual in this case means there are 2 separate counters in the one package
you can use one or both of them depending on circuit requirements

like with all CMOS and logic chips, its a wise idea to ground to 0V rail any inputs of a section that are not being used. This stops all sorts of weird fault symptoms

Dave

 

[Harald Kapp]

Here is an example for a single digit counter using the 4520.
For an n-digit counter you need to cascade n counters, the datasheet tells you how to connect the counters for cascading.

The 4520 is a binary counter. To display the count on a 7-segment display you will need an additional BCD-to-7Segment decoder, one for each digit.


However, the 4520 is a binary counter, meaning it counts from 0...15, So you can't build a decimal counter from this chip and your display will show weird symbols once the count goes over 9.
If you can find one, I suggest looking into the 4026 or 4033. These chips are not only decade counters, they already include the decoder to drive the 7-segment display.
Or look into the 4510 which can not only count up but also count down. Here is a complete circuit to evaluate the 4510.

Harald

 

[McDroogie]

Can I at least initiate a countdown or count up from 0-9? If so where can I start?

 

[Miguel Lopez]

From the datasheet it seems that HEF4520 is just a count-up counter, so, there is no possibility to count down.

You can start it at zero, fixing initial conditions at pins 7 and 15. If these pins goes HIGH, then the counters will be reseted to zero.

 

[Harald Kapp]

You will still need a BC D to 7-segment decoder, though.

 

[McDroogie]

So is there a chip within that same family that acts as a decoder? And so I have to wire them with the counter and 7 seg display?

 

[Harald Kapp]

You could use a 4511. But I would use the 4510 counter with integrated decoder. Saves some wiring.