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Member

Join Date: Mar 2021
Posts: 7

7-Segment with CD4511BE BCD Using Problem

09/14/2021 4:45 AM

Hello, all

Hardware:

CL5631BW - 3 Digit 7 Segment Display

CD4511BE BCD Decoder

Attachment:

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

Problem:

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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Guru

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#1

Re: 7-Segment with CD4511BE BCD Using Problem

09/14/2021 5:19 AM

It sounds like you have the chip plugged in backwards....

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Guru

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#2

Re: 7-Segment with CD4511BE BCD Using Problem

09/14/2021 7:52 AM

You are correct

The outputs of the decoder are active high

Whereas the display is a common anode device

You need to insert inverters between the outputs of the decoder and the inputs to the display.

What are you using as power rails there may be a 74 series cmos compatible decoder which is suitable (like anSN74LS47N but with LS replaced with a CMOS compatible technology).

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#3

Re: 7-Segment with CD4511BE BCD Using Problem

09/14/2021 8:11 AM

The datasheet (see page 5) shows the 4511B wired to a common cathode 7 segment display. I think you'll either have to replace the display with Common Cathode or the driver chip with common anode.

CD4511BE pdf, CD4511BE description, CD4511BE datasheets, CD4511BE view ::: ALLDATASHEET :::

A better option (as Randall suggested) is to put inverters between the driver and display.

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