Integrated circuit?

Question

Can anyone explain me how work the IC SN 7490?
Thanks!!!

Answer 1

Try this web site (I'll save time this way)

http://electronics.howstuffworks.com/digital-clock5.htm

It explains how the 7490 works (found it with google)


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added comment

I used a variety of ttl IC's in my teens (as did poster #3). Now that inexpensive MCU's are available like PIC's I do all my projects with them. Look at the photo http://upload.wikimedia.org/wikipedia/en/thumb/5/50/TTL_Clock.jpg/300px-TTL_Clock.jpg
That is a real time clock made from TTL. One can program the entire thing into a single PIC and have it doing lots of other stuff too.
photo from http://en.wikipedia.org/wiki/Transistor%E2%80%93transistor_logic#History

Answer 2

It is a binary coded decimal (BCD) or decade counter. It counts from 0 ... 9 then resets to 0 (and starts over). It counts when you apply the clock input.

It is a ripple counter, meaning, the least significant bit must change state before its state (0 or 1) is transmitted to the next significant bit, and then when the 2nd bit changes that information is rippled to the 3rd bit, then the 3rd bit is rippled to the 4th (most significant) bit.

side note:
In a synchronous counter (like the 74190), the state of all 4 bits is ready at the inputs to every register, then when the clock edge comes, all bits are changed (to the next count value) simultaneously.

In a straight binary counter the counter would count from 0 ... 15 then back to 0. Combinational logic decodes the "9" from the 7490 and forces the 4 flip-flop registers back to zero on the next clock edge.

The 7490 is actually split into 2 counters, a divide by 2 and divide by 5 (2 * 5 = 10 -- one decade). You can use it as such, if you need a divide (the clock frequency) by 5. Mostly people use it as a decade counter.

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Answer 3

go to the website