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SN54LS181: SN54LS181

Chanabasappa Byalal1
Prodigy 10 points
Part Number: SN54LS181

Hi Experts,

We have managing obsolescence management in our earlier design, product has M74HC181 device and now we need to replace it with SN54LS181, is the LS181 will meet all the specification of HC181 logic family? 

Can any one advice on this

Thanks

Chanabasappa Byalal

  • 0
    Guru 280470 points

    LS is an older, bipolar family with much higher current consumption, asymmetric drive strength, and TTL output levels.

    If the 181's outputs are connected to some CMOS input, it is unlikely to work without additional pull-up resistors.

  • 0 in reply to Clemens Ladisch
    TI__Guru 62930 points

    I agree with Clemens, they are not identical.

    An analysis would need to be performed to insure that timing and input thresholds are still met at system operating voltage(s).

    The LS device has very weak VOH drive capability.  A pullup could help resolve this.

    I spot checked a few delays to the HC datasheet, and they are similar at the 5V node.

    If this answers your question, please click "This Resolved My Issue"
    Regards,
    Wade