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Original question:

CD74ACT74: D Flip Flop: How to reliably clock or reset a FD lip Flop with a glitched signal.

CD74ACT74: TPLH/HL minimum timing limit at -55C

Tony Kleman
Intellectual 380 points
Part Number: CD74ACT74

I'm seeing marginal failures to the minimum prop delay limits at -55C.   Measuring 2.1-2.4nS when the minimum limit is 2.4nS.  I know, very close.  Make me want to understand how TI screens these parts.   Are all parts tested at -55C?  The part number on my device is 74ACT74M

  • 0
    TI__Mastermind 44775 points

    Hey Tony,

    These specs are associated with a 50 pF load as shown in the parameter measurement information. Is this the same load you have? Lighter loads can result in lower propagation delays.

  • 0 in reply to Dylan Hubbard
    Intellectual 380 points

    The Advantest 93K ATE specifies the load as 50pF.   I realized the measurements are so close to the limit that even small differences like the capacitance loading are meaningful.   What I would really like to know is if T.I. actually screens these parts at -55C?    On many other suppliers and product lines I have found that parts are screened at hot only and cold limits are guaranteed without screening.

  • 0 in reply to Tony Kleman
    TI__Mastermind 44775 points

    Hey Tony,

    A lot of testing, simulation, and statistical analysis is done to come up with the specs in the datasheet. However, this device was acquired from Harris, so I can't comment specifically how it was determined, but all parts do undergo a final test at the end of manufacturing. This test is likely only done at 25 C.