SN74LVC1G126: tpd range and tolerance under 7ns tr/tf and 1.8V VCC

Garrick Dai

Part Number: SN74LVC1G126
Other Parts Discussed in Thread: SN74AUC1G126

My customer need tpd parameter accurate range and tolerance under their actual condition-- Vcc=1.8V and tr/tf about 7ns. The spec in datasheet is under condition of tr/tf=2ns, so it is different. Pls help check. Thanks.

over 7 years ago

0 Emrys Maier over 7 years ago

TI__Guru* 97066 points

Hi Garrick,
A slower input will definitely affect the total delay time. The input delay is being increased by ~3.5ns (half of the rise or fall time, assuming a smooth transition), which will directly add to the existing datasheet numbers.

Starting from the 15pF load, -40C to +85C table (1.7ns to 6.9ns), they should expect to see a delay between 1.7ns and 9.4ns

Tolerance for the propagation delay isn't specified -- we can only guarantee those values given in the datasheet. If their system requires a more accurate delay time, they might want to either consider a system change or a different device (for example, SN74AUC1G126).

0 Garrick Dai over 7 years ago in reply to Emrys Maier

TI__Intellectual 1660 points

Thanks Emrys.

It seems just add 3.5ns based on original 6.9ns for upper limit, but how about lower limit(1.7ns)? Will 1.7ns+3.5ns as well or other? Customer still want to have accurate range. Thanks.

0 Emrys Maier over 7 years ago in reply to Garrick Dai

TI__Guru* 97066 points

Hi Garrick,
Unfortunately, it doesn't work that way. The minimum is still 1.7ns. You can't say for certain that the delay will be longer under all circumstances, but we can say for certain that it _could_ be up to 1/2 of the input rising edge longer with relative certainty.

Any good system designer will design with the _worst case_, which is what I have provided for both the maximum and the minimum.

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SN74LVC1G126: tpd range and tolerance under 7ns tr/tf and 1.8V VCC