7- Segment Display getting on reversely

Thread Starter

Sonal Pawar

Joined Oct 28, 2021
2
Sir,
I am using FYS-15011BS-11 7-segment common anode display and DM7447N IC to drive it. But Whenever I give inputs to its A B C D inputs according to the truth table I am getting reverse output, it means when I apply A B C D INPUTS as 0 0 0 0 respectively 7 segment should display '0' means a b c d e f segments should get on and g segment should get off. But I am getting exactly opposite behaviour. a b c d e f segments are getting off and g segment is getting on. What could be the reason ? Can you please guide me. It is grateful if you can provide the datasheet of mentioned BCD to 7 segment decoder IC 9603B DM7447N.
 

boostbuck

Joined Oct 5, 2017
88
Your schematic is missing the normal current limiting resistors required for an open-collector driver, as illustrated in the attached schematic I found on the web:

1635416799311.png
 

Dave Lowther

Joined Sep 8, 2016
122
please find the attached schematic.
You don't show any connections to pins 3, 4, and 5. Are they connected to anything?
I don't see how leaving them unconnected would cause the segments' illumination to be the opposite of what is expected, but it would be a good idea, if they are currently unconnected, to connect pins 3, 4 and 5 together and then connect the junction via a 1K resistor to 5V.

1635419877113.png
 
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