AD8556: Parity-fuse and programming


I have another question regarding fuses and parity.

The data sheet states:
"After the master fuse is blown, that is, after the AD8556 is programmed, the output from the parity circuit (PAR_SUM signal) is fed to PARITY_ERROR. When PARITY_ERROR is 0, the AD8556 behaves as a programmed amplifier. When PARITY_ERROR is 1, a parity error is detected, and VOUT is connected to VSS."

Does that REALLY mean, that programming (also the master fuse) with false parity fuse-bit is possible - and after blowing master fuse the device acts as dead (Vout= Vss)??
If so, this would be a very bad and nasty "joke". I can't believe that AD has conciously designed it that way! Unbelievable - "It's not a bug, it's a feature"?????

  • 0
    •  Analog Employees 
    on Jul 23, 2019 7:04 AM

    Hi Alex,

    Here is the reply from the product owner.

    "If the user is using the permanent fuse setting option they must ensure that they are programming valid parity data. As indicated in this thread, if invalid parity data is programmed wrong the output is pulled high. The user should validate the output before using the permanent fuse setting."