One single IC can be used to count form zero 0 to nine 9 directly on a Common Cathode type 7-segment display. The count can be increased by simply giving a high clock pulse; also more than one digit can be created by cascading more than one CD IC. So if you have a 7-segment CC display on which you have to display numbers that are being counted based on some condition then this IC will be a perfect choice. We have 7 output pins naming from Out A to Out G which is directly connected to the 7-segment display. The 7-segment pins will increment the count by one number each time when the clock pin pin 1 is made high. They simply have to generate a pulse of low voltage 0V and high voltage 5V.
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Alternative options CD is a 5 stage johnson decade counter belonging to a CD series. It has many distintive features than other decade counters. Firstly, it is ideal for applications having low power consumption requirement. Additionally, the advantage of using this IC is that it has a built-in decoder circuit along with the counter and it can be connected to all types of 7-segment displays.
The ten decoding outputs go high sequentially on positive edge of input clock cycle. CD Pinout Diagram This picture shows a pinout diagram of 5-stage johnson decade counter. It is a 16 pin IC available in different packages. Pin Configuration Details This table lists the pin description of johson counter along with the funtionality.
When it is HIGH, counter starts counting. CLK Inhibit Clock inhibit input enables clock pin. When it is LOW or connected with the ground of the circuit, it enables Clock pin. When it is HIGH, the clock pulse is inhibited.
After counting up to 9, it produces a pulse signal. It is used in cascading to clock the succeeding decade.
Gnd This pin is connected to the ground of circuit Not 2 Out Ungated C segment output pin is only used for some dividing functions. Vcc Voltage supply is connected to this pin. Can drive a common cathode 7-Segment display directly The clock input is Schmitt triggered to provide a reliable clock signal and therefore it has no fall and rise time limitations. Where to use it? This CD IC performs digital displays as it can convert input into a decimal digit which can be seen on the Common Cathode Type 7-segment display.
Although, we can use along with microcontrollers for displaying analogue values but it will be a wastage of resources. This IC can count from 0 to 9 but you can increase the counting by giving high clock pulse. Therefore, it can be used in all those applications and projects whose operation involves counting events or objects based on some condition.
How to use CD Counter? The seven decoded outputs are connected directly to the inputs of the Common Cathode Type of 7-segment display. After that pressing the switch, counter starts and gets incremented by 1 after every positive edge of clock. The clock inhibit pin is connected to ground to send the clock signals to IC. First time number 1 will be displayed on the 7-segment display. On pressing the switch second time, number 2 will be displayed and the process continues till counting reaches to 9.
After that, it will restart from 0. Ouput Pattern Table The table given below shows the sequence of outputs from the CD counter IC after pressing switch connected to the clock pin and how it is displayed on the 7-segment display.
Enable output pin is set to HIGH. It drives the cascaded IC clock pin when its own counter reaches the value of 9. However, If you want to restart the counter from 0, press the reset pin. CD Example Circuits In this section, we will see some basic and popular example circuits of this johnson counter. Firstly, we will see an single digital circuit that can count from After that we will discuss a 2 digit display circuit that can count from But you can also extend this circuit to count upto At the end, we will see a practical example such as digital clock design.
Single Digit Counter Example This circuit can count from Because we use only one CD IC and one seven segment display. The speed of counting display depends on the clock frequency.
Pin3 should remain active high. We can use pin15 to stop counter from working. You can change the frequency according to your requirement.
This works similar to the last circuit. But the only difference is the use of CO pin and clock pin use for second display. Because we want to increment 10th place 7-segment value only after unit place 7-segment complete its counting from and resets.
After every reset, CO pin sends active high signal to second IC. In short, This signal acts like a positive edge clock. Therefore, counter increments its value on every reset of first johnson counter integrated circuit. Additionally, you can add one more digit to this circuit. Digital Clock using CD In conclusion, we will provide you an practical example. This is circuit diagram of digital clock using CD Therefore, if you do not want to use microcontroller.
You can still design a digital clock using this digital decoder. Check this complete video guide for step by step guide.
Applications Digital Clocks, Timer circuits and frequency dividers Registers to process data Counter projects to count events, objects or people Multiple ICs can display larger numbers between Eliminate the need of microcontroller for counter design Alternative options.
CD4026 - CD4026 Decade Counters/Dividers
CD4026 5-stage Johnson decade Counter Examples