Simple Display Driver Circuit

Can you imagine the display on your calculator or phone that needs a tiny translator.

A display driver circuit is like that translator.

It gets information from a tiny computer microcontroller and changes it into a special code that the display understands.

This code tells the display exactly which lights or pixels to turn on to show you letters, numbers or even pictures.

So, thanks to display driver circuits, you can see all the cool things on your electronic devices.

Circuit Working:

Parts List:

This circuit demonstrates how a seven segment display can be driven using the CD 4033 5 stage johnson decade counter IC.

This IC combines a counter and decoder in a single package converting johnson codes into seven segment decoder output to drive a common cathode display.

The display presents the counts in a numerical format.

Powered by a 9V DC supply, the circuit connects the IC outputs to the common cathode seven segment display LT 543.

When the Clock Enable, Strobe and reset pins are grounded the IC continuously counts up to 9.

This cycle repeats until the reset pin receives a high pulse.

The CD 4033s input is a sensitive schmitt trigger easily accepting positive to negative transition pulses to initiate counting.

As the counter advances the outputs provide decoded signals that can drive the numerical display.

Multiple displays can be connected to count up to 100, 1000 etc. by cascading CD 4033s.

Connecting the carry out pin 5 of one IC to the clock Input pin 1 of the second IC allows the counter to continue with the second IC starting counting when the first IC completes 9 counts.

This cascading setup can be expanded to include many ICs.

Formula:

The following are some important formulas and factors to take into account while creating a display driver circuit that includes the CD 4033 IC:

Compute Clock Frequency:

The clock pulses given to the CLK (clock) input pin cause the CD 4033 integrated circuit to advance its count.

Establish the required refresh rate or counting speed (in Hz, or hertz).

Determine the clock signals period T:

T = 1​ / f

where,

• f is the desired frequency of operation in Hz.

Calculating the Current Limiting Resistor:

To prevent the LEDs in the seven segment display from receiving too much current, each segment needs a current-limiting resistor.

Using ohms law, determine the resistor Rs value.

R = ​V_DD​−V_LED​​ / I_LED

where,

• The supply voltage is represented by V_DD, the forward voltage drop across the LED segment is represented by V_LED, and the required current via the LED is represented by I_LED which is around 10–20 mA.

Calculating a Debouncing Capacitor:

To debounce a push button switch and avoid repeated triggering from mechanical bouncing, add a capacitor if you are using it for manual input (such as clock input).

With the use of the RC time constant, one may determine the usual value of the debounce capacitor C.

τ = R * C

• Select C in such a way that the time constant τ is just right to filter out switch bounce without causing the response to be unduly delayed.

Note:

These equations and factors offer a basis for developing and figuring out the specifications of a display driver circuit that makes use of the CD 4033 IC.

Depending on the needs of the application and the particular component specifications, adjustments can be required.

How to Build:

To build a Simple Display Driver Circuit you need to follow the below mentioned steps:

Connect Power Supply:

• Connect the 9V DC power supply to the breadboards power rails usually the red terminal for positive and black terminal for ground.

Connect CD 4033 IC:

• Place the CD 4033 IC on the breadboard.
• Connect pin 8 ,pin 2 and pin 14 of CD 4033 to the ground.

Connect Display:

• Connect the common cathode seven segment display to the breadboard.
• Connect the common cathode pin to the ground.

Connect Resistors:

• Connect current limiting resistor R3 to the displays segment pins 3 and 8 to limit the current.
• Connect the rest of the display pins with the relevant pinouts of the IC 4033.

Connect Control Pins:

• Connect the clock pin 1, clock enable pin 2, strobe pin 3, and reset pin 15 pins of the CD 4033 to the appropriate control components e.g. switches or pull down resistors connected to ground for clock enable, strobe, and reset.

Connect Clock Input:

• Connect a clock signal to the clock pin 1 of the CD 4033 to increment the count.
• This can be a pulse generator or a simple push button switch connected to ground.

Connect Circuit Ground:

• Ensure that all grounds in the circuit are connected together.

Test the Circuit:

• Apply power to the circuit and test the functionality by pulsing the clock input and observing the seven segment display as it counts up.
• Adjust the clock signal frequency as needed.

Note:

• This basic setup can be expanded by cascading multiple CD 4033 ICs to count higher numbers or by adding additional control logic for more complex functionality.
• Always refer to the CD 4033 datasheet for the specific pinout and electrical characteristics.

Conclusion:

A display driver circuit is an essential component in electronic devices converting input signals into control signals for displays.

It enables the presentation of information in a visual format making it crucial for a wide range of applications, from simple numeric displays to complex graphical interfaces.

References:

Display driver

Datasheet IC CD4033