SN74LV1T08: Input transition rise or fall rate

Sho Ikeno

Part Number: SN74LV1T08

Tool/software:

1. Input transition rise or fall rate is determined to be 20ns/V in the datasheet. Is this applicable between VILmax（0.8V）～VIHmin（1.35V)? Device is used under the condition of Vcc=3.3V, Vin =1.8V

2. under the above condition, the voltage difference is 1.35-0.8=0.55, therefore is the rise/fall time calculated as 20ns*0.55V=11ns?

3.what kind of issue can be expected if the transition time is exceeded?

Regards

4 months ago

0 Clemens Ladisch 4 months ago

Guru 316440 points

1. The rate must be fast enough at every point of the edge (between V_IL and V_IH).

2. Yes; if the voltage rises or falls with constant speed, then it must take no longer than 11 ns to transition between V_IL and V_IH. But this limit is not for the average rise/fall rate, so if the edge is not straight, then even the slowest part of the edge must be faster than 20 ns/V.

3. Oscillations at the output; see [FAQ] How does a slow or floating input affect a CMOS device?

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SN74LV1T08: Input transition rise or fall rate