Details IC cd4017
IC cd4017 is a decimal counter IC that counts system 10, it counts clock pulses. When we put the pulse signal into the clock pin, the IC will count the pulse and output 10 outputs corresponding to 1 clock pulse.
This IC is commonly used in counting circuits, timer circuits, LED matrices, LED chaser and other LED projects. Binary counter or binary decoder. Can be used as a divider. Remote metering, automotive, medical electronics
IC cd4017 Overview
The IC CD4017 is used for counting applications, it has the capability to turn on 10 outputs sequentially in a pre-defined time and reset the count or hold it when required. It also has the capability to indicate the status of counting using Carry pin. This is commonly used for Led chasers and other logical output projects, so if you are looking for an sequential decoded counting IC that can count up to 10 then this IC will be your right choice
The IC can work from 3V to 15V, but normally powered with +5V to the Vdd/Vcc pin and the Ground/Vss pin is connected to ground. We have 10 output pins ranging from Q0 to Q9, these pins can be connected to any load but we are using LEDs here as shown in the circuit below.
This IC will increment the count from 0 to 9 (Q0 to Q9) each time it senses a high pulse from the clock pin (pin 14). So we need a clock source to keep this IC ticking, this clock source can be a simple Timer circuit that could generate pulse or a microcontroller like Arduino, PIC etc to generate our custom pulse using I/O pins.
The output changes sequentially from Q0 to Q9 for every high pulse from the Clock pin, but this sequence can be interrupted by two pins. They are the Clock Enable (pin 13) and Reset (pin 15) pins. These pins are held low (0V/grounded) by default, but when the Clock Enable pin is made high the counting pauses.
For example if the count was at pin Q3 when the Clock enable pin was made high, then the count will pause at pin Q3 irrespective of any high pulses from clock and will continue incrementing only when Clock Enable is made low again. Similarly, if the reset pin is made high. The count will reset itself back to Q0 and will stay there until Q0 is made low again.
We have another pin called the carry out pin (12th pin), this pin will stay low (0V) by default. But when the IC completes counting up to 10, the pin will go high and will remain high till it counts till 5, when its 5 it will go down (0V) and turn on again when it reaches 10. The timing diagram of the IC cd4017indicating the state of Output pins and Carry pin for every high pulse signal is shown below.
The CD4017 is a CMOS Decade counter IC. CD4017 is used for low range counting applications. It can count from 0 to 10 (the decade count). The circuit designed by using this ic will save board space and also time required to design the circuit. CD4017 is as ‘Johnson 10 stage decade counter’.
This IC is also used in electronic industries, automotive industries, manufacturing medical electronic devices, alarms and in electronic instrumentation devices.
Pin number 8 acts as ground and it must be connected to negative supply voltage & pin number 16 is the supply pin for CD4017 and it is connected to positive voltage supply.
The pin 12 is supplied with the CARRY OUT signal. It completes one full cycle for every 10 clock cycles. This is used to ‘ripple’ the IC, which means to delay in counting operations.
This is the timing diagram of the CD4017 with, shows us the comparison and also explains the counting sequence of the outputs, shifting from one pin to its next.
If we observe that, before applying the clock signal, the RESET is set to High, so the reset pin input sets all the output to their initial state.
Then the output of the first output pin 3 will be high. Next this output is shifted to its next output pin and this sequence continues till the next clock cycle.
The LED sequencer circuit by using CD4017 and IC 555 is shown below. This circuit is also called as “LED chaser circuit”
Primarily it is important to remember that, as the CD4017 is a CMOS device, it is very sensitive to the static electricity.
The LED sequencer circuit uses the 555 timer to produce the clock pulses required for CD4017, which is operated in Astable mode. Output of this Astable timer circuit is connected to the clock signal input of CD4017.
It produces stream of pulses continuously, in which the each pulse increases the counter by 1. So thus each LED will light up and then off before turning on its next LED in the sequence.
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