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7-Segment with BCD LED Driver Problem

Posted by: Aubreyhu on 09/23/2021

Hi, all

CL5631BW - 3 Digit 7 Segment Display
CD4511BE BCD LED Driver Decoder

The BCDA inputs are wired with 680 Ohm Resistor and the outputs are wired with 680 Ohm Resistors to the 7 Segment correctly.

All Numbers shown on the Display are inverted (All segments that should be illuminated are dark and vice versa).

I think the decoder is for Common Cathodes. Is it possible to change the mode for the decoder to Common Anode? Thank you in advance.


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CD4511BE BCD LED Driver Decoder 20.35 KB


Submitted by PI-Zek on 10/02/2021

Hi Aubreyhu,

The CD4511BE BCD decoder is used for common cathode applications. A common cathode driver such as CD4511 will switch the logic of the segments between +Vcc and open circuit to drive each individual anodes in a common cathode 7 segment LED display.

CL5631BW is a common anode 7 segment display with +Vcc supply as the common connection. Each cathode for each segment will be pulled low to ground by the transistors driven by a common anode driver.

So if you choose a common anode for a common cathode decoder, you need to invert the logic of its outputs by using an external circuit. You can also choose to use a common cathode 7 segment display for your CD4511BE BCD LED decoder to match its application without additional components or vice versa.