7490 mod 10 counter
188金宝搏app苹果下载 188app 188

7490 Decade Counter Circuit (Mod-10) Designing

IC 7490isAsynchronous mod-10 Counter IC. In this article, we are going to study IC 7490 Decade Counter Circuit. IC 7490is also known asBCD Counter, Decade Counter,andmod-10.These names are given based on theFunctionalityandWorking PrincipleofIC 7490.

Counter Designing using 7490 IC:

In the discussion ofCounter ICs, some basic terms will be used a lot. That’s why we need to know some basic terminology whileDesigningany ofCounter.

Asynchronous Counters :

InCounters ICsthere are so manyClock Inputs thatare present based on the Internal Structure ofFlip-Flops.If all theClock Inputof theFlip-Flopsare not driven(controlled) by the sameClock Signals(Pulse)then the Counter is Defined asAsynchronous Counters.ICs 7490, ICs 7493,etc. are examples ofAsynchronous Counters.

Synchronous Counters :

If all theClock Inputof theFlip-Flopsare driven(controlled) by the sameClockSignals(Pulse)then the Counter is Defined asSynchronous Counters.ICs 74160, ICs 74163, ICs 74168, ICs 74169etc. areSynchronousCounters.

Clock Signals(Pulse):

It is a continuoushigh-lowsignal and is represented as a square waveform.

BCD :

BCDStands forBinary Coded Decimal.It Simply means theDecimal numberis replaced by their EquivalentBinary Code.for e.g. theDecimal number 10is replaced by there equivalentBinary Code 1010

mod-n :

modrepresentModulus of Counterandnbelongs to an integer.ModulusofCounteris the total number ofUnique Statesit should pass through in one completeCounting Cycle.It means if we need to designmod-6 counterthen it should pass throughsix Unique Statesin one CompleteCounting Cycle.That is 0000(0), 0001(1), 0010(2), 0011(3), 0100(4), 0101(5), then again come back to 0000(0).

Frequency Division :

As we know that each and everyCounter Circuitis made up ofFlip-Flops.if common Clock Signals do not trigger the Clock Inputs of all Flip-Flops then the output produced by suchSequential Circuit以前总是减少50%的吗Cycle. If you observe the Following figure carefully your all doubts will get clear automatically related toFrequency Division.IC 7490 can be used as a frequency divider circuit. It can divide the input frequency by 2, 5, and 10.

Frequency division of square wave

Sequential Circuit

If any Circuit starts its Counting in series i.e., the count may be in increasing order or decreasing order.ICs 7490 decade counteris an example of aSequential Circuit.Because its Counting Sequence is 0,1,2,3,4,5,6,7,8,9. its Count always in the upward direction(in increasing order) that’s why it is also known asUp Counter.

Now we are going to a little deeper part and we will study its basic structure known as Block Diagram. Before going to that part I want to tell you one thing don’t confuse betweenBlock DiagramandPin Diagram(Pinouts)of any ICs. There is a huge difference between Block Diagram and Pin Diagram later on we will see that.

Block Diagram of 7490 counter IC :

Let us understand the Block Diagram of ICs 7490 which is given in the following figure. And this is one of the major parts of this article so keep reading with high concentration.

7490个十进制计数器circuit

Now let us start a brief introduction of ICs 7490. Start with its input terminals

VCCandGND:

VCC and GND are the input pins of ICs 7490 which are used to give power supply to the ICs. These input terminals are generally present in all devices to give power supply to the devices. VCC stands forVoltage Common Collectorsand in most cases, it is referred to as high voltage with respect to GND(Ground) terminal. It may be positive and negative with respect toGND(Ground).

Clock Inputs (AandB) :

The terminal represented as A and B in the above figure are known as Clock Inputs. These inputs terminal are used to provideClock Signalsto the ICs. It presents in all Counter ICs for the same purpose.

Set Inputs(S1 andS2):

The input terminals S1 and S2 are knowns as Set Input terminal because it is used to set or load any data(state) to the ICs. Here data(state) means any random number say 0011(3). If we want to start our counting from 0000(3) then we need to Connect it withVCCorLogic 1because Set Input is Active High input Set Inputs Play its magical role and it forces IC to start its Counting from 0000(3). By default, ICs 7490 Start its Counting from 0000(0) andpre-set inputis absent in this IC so we can’t use this Set Input(S1 and S2). That’s why we always connect it with GND(Ground).

IC 7490 Decade Counter CircuitPin Diagram:

IC 7490 is a 14 pin DIP(dual inline package) ic. The pin description of 7490 is as follows,

IC 7490 pinout diagram

Working of7490 Decade Counter Circuit:

7490 mod 10 counter

It’s a BCD counter it can count from 0 to 9 (10 states), hence it is called a mod-10 counter. It has two separate counters, a mod 2 counter, and another mod 5 counter. Together they form a mod 10 counter. The first bit is given by mod 2 counter its output is used as a clock for the second mod-5 counter. Give clock to clkB to use as mod 5 counter and give clock to clkA to use as mod 2 counter.

7490 Mod counter :

7490 mod 5 counter

When the clock is given to the mod 2 part of the ic it counts 0 and 1 its output Qa is given to the mod 5 part of the ic. By combining both the counters it counts from 0 to 9 in BCD format.

Other than this there are two reset pins R0, R1, and two set pins S0, S1. Making the reset pin high or set pin low counter will be reset to 0000 (0). If we make the reset pin low and set pin high the counter will be set to 1001(9), the highest count.

7490 mod 2 counter

We can increase the count to 99 (mod-100) or 999 (mod-1000) as per our requirements. The highest output of the previous IC is used as a clock to the next ic. It can work as a mod-10 counter by connecting the 2nd clock input(pin 1) and QA. And connecting all rest pins to the ground and giving pulse to pin 1. It can work as a mod-6 counter by supplying pulse at input 1 and grounding reset pins R3 and R4 and connecting QA with input 2.

7490 IC can work asBCD(binary coded decimal) counter. It is used to store decimal digits in the form of 4-bit binary numbers.

One Reply to “7490 Decade Counter Circuit (Mod-10) Designing

  1. The above is a perfect, compressive, and excellent webpage that incompasses the most common ways to use the 74xx90 integrater circuit.
    BONUS: You included the parts’ pin numbers <– this makes teaching electronics much easier, forever!

Leave a Reply

Your email address will not be published.Required fields are marked*