The CD4511 IC is a 7-segment driver. It is a BCD to 7-segment decoder which can convert a binary to a decimal number. We can display decimal numbers by connecting a 7-segment display to the outputs of CD4511. On top of that, It can operate within a voltage range of 3-18V. All the inputs are protected from electric discharges. Additionally, it has built-in IC testing pins such as Lamp test, blanking, and strobe.
CD4511 Pinout Diagram
As you can depict from the pinout diagram CD4511, it consists of 16 pins. We use seven output pins from a-f to connect the 7-segment display. Four input pins are used to connect BDC coded inputs. The rest of the pins are either power supply or testing pins.
Pin Configuration Details
This CD4511 has four BCD inputs, 3 control inputs, and 7 outputs. The details of all these pins are mentioned in the table below:
|Pin No.||Pin Name||Description|
|1, 2, 6, 7||A, B, C, D||4 BCD inputs|
|3||~LT||Lamp test input is used to test the display.|
|4||~BL||Blanking input is used to turn−off or pulse modulate the brightness.|
|5||LE/~Strobe||Latch Enable or Strobe input is used for storing BCD code.|
|8||Vss||Ground of the circuit.|
|9, 10, 11, 12, 13, 14, 15||a, b, c, d, e, f, g||Seven segment outputs|
|16||Vdd||Positive power supply|
CD4511 BCD decoder Features
- It has a lamping test and blanking inputs.
- Low power dissipation.
- Balanced propagation delays
- Hold time is zero
- Latch input for storing BCD code.
- Balanced transition time
- Operating temperature range: -40 °C to 85 °C
- Outputs have high sourcing currents up to 25mA
- 7447, SN5446A
Where to use BCD to Seven Segment Decoder?
It is widely used to display numbers by driving a common cathode seven segment display. For example, you are using a counter which provides output in BCD format. You want to use this BCD output with 7-segment. This IC will be helpful to convert BCD encoded signals into 7 signals. It can also be used to decrease the input and output ports of microcontrollers.
How to use CD4511 BCD Decoder?
The CD4511 IC has a latch along with the decoder inside IC as shown in the functional diagram. To use this IC, connect the input pins with the pushbuttons and output pins with the 7-segment display.
The truth table showing the pattern of output on applying different inputs is given in the table.
In addition to input pins, CD4511 BCD driver has three control inputs ~LT, ~BLE, and LE. Lamp test input is used to test the display. When a LOW signal is applied at this input, it turns ON all the segments. On the other hand, Blanking input behaves in the opposite manner. It turns off all the segments when it is applied with a LOW logic level. Latch enable input depends on the ~LT. When ~LT is LOW, the output will be 0 even if the LE is HIGH. Therefore, for normal operation, it should be HIGH. The latch enables input is used to store the display.
When it is low, the 7-segment display attached to its output will display the value corresponding to the value on the data inputs and when it is high, the display will show the last digit regardless of changes on the data lines.
Truth Table BCD to Seven Segment
This section consists of examples circuits using CD4511 seven segment driver IC.
Digital Counter Example
In this example, we use a counter CD4520 BCD counter to provide inputs to 4511 pins instead of push buttons. Therefore, this seems to be a more practical example than the last one. CD4520 BCD counter provides BCD encoded inputs to 7 segment drivers. As you can observe from this proteus simulation, this circuit counts from zero to 9.
This IC is used in:
- Display drivers of Counter, Computer, Calculator, cockpit, etc.
- In displaying and multiplexing multiple signals
- Driving incandescent displays