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The 7447 Seven Segment IC

The 7447 Seven Segment IC

Introduction to the 7447 IC

The 7447 IC is a popular seven segment display driver integrated circuit (IC). A seven segment display is a very common way to display numbers using LED or LCD displays. The 7447 takes a 4-bit BCD code as input and drives the appropriate segments of the display to show the number represented by the BCD code.

Some key features of the 7447:

  • Contains BCD to 7 segment decoders
  • Can drive common anode or common cathode displays
  • Has active LOW outputs to sink current
  • Wide operating voltage range of 3-15V

Pin Diagram

The 7447 has 16 pins as shown in the pin diagram below:

1BLANKBlank display input
2-5A-DBCD inputs
6LTLatch input
7BIBuffer input
8-15a-gSegment output pins
16VccPositive supply

Internal Block Diagram

Below is a simplified block diagram of the 7447 showing the main internal components:

The BCD inputs feed into a decoder which converts the number to outputs for the 7 segments. The latch input can be used to hold the currently displayed value. The buffer input can override the BCD inputs and blank the display.

Example Circuit

A simple example circuit to drive a common cathode 7 segment display is shown below:

The 7447 sinks current through the desired segments to light the LEDs. Current limiting resistors are used for each segment.


  • Digital clocks
  • Electronic meters
  • Basic numeric displays
  • Counters
  • Timers

The 7447 provides a simple way to interface 4-bit binary coded data to a 7 segment display. Some applications include:

Pros and Cons


  • Simple BCD to 7 segment conversion
  • Can drive LED or LCD displays
  • Wide operating voltage range


  • Limited to 4-bit BCD input
  • Cannot directly drive 7 segment displays with common anode configuration

Frequently Asked Questions

What is the difference between 7447 and 7448?

The main difference is that the 7448 has active HIGH outputs while the 7447 has active LOW outputs. So the 7447 sinks current and the 7448 sources current.

How do I choose current limiting resistors for a 7447 circuit?

Check the max current rating for your display segments, usually 20mA. Use Ohm’s Law to calculate the resistor value to limit current to less than the max rating.

Can I cascade two 7447 to drive 8-bit input?

Yes, you can connect two 7447 in series to handle 8-bit BCD input. The first handles the lower 4 bits, and the second the upper 4 bits.

How do I drive a common anode 7-segment display with a 7447?

Use PNP transistors between the 7447 and the display to invert the signals. The 7447 sinks current to turn on the PNP transistors which then source current to the display.

Can I use a 7447 to drive more than one 7-segment display?

Yes, you can connect multiple displays in parallel as long as you adjust the current limiting resistors accordingly.