What would be the difference in using a 7-segment decoder with active-high outputs vs active-low outputs, to driver an LED display?


1 Answer 1


Some 7 segment displays are common anode, which require a decoder with an active-low output. Others are common cathode, which require an active-high output. Choose the decoder appropriate to the display that you want to use.

  • \$\begingroup\$ @stevesy It seems common-anode displays are more common, as the decoder circuitry in bipolar 74xx series devices drew more power when driving common-cathode displays. Whether this is also the case with CMOS decoder ICs like the 74HC/HCT series, I am not certain. \$\endgroup\$
    – MattyZ
    Commented Dec 6, 2013 at 5:51

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