SN74LV244A: undershoot for around 2ns

Hi team,

My customer is using SN74LV244APWR and SN74LV06APWR and have confirmed a undershoot for VI that is exceeding AMR (-0.5V)

It is the same customer with the 2 threads below.

https://e2e.ti.com/support/logic-group/logic/f/logic-forum/1093626/sn74vmeh22501a-undershoot-for-around-10ns

https://e2e.ti.com/support/logic-group/logic/f/logic-forum/1112960/sn74vmeh22501a-imin-and-imax-value-in-ibis-model/4124209#4124209

Below are the measured wave form respectively:

SN74LV244APWR

minimum: -1.18V (exceeding -0.5V for 2.00ns)

SN74LV06APWR

minimum: -0.58V (exceeding -0.5V for 0.32ns)

The customer already know that in the datasheet it says:

"The input and output negative-voltage ratings may be exceeded if the input and output current ratings are observed."

but it is challenging for the customer to measure the current and check if it is under the rating or not.

They also checked the IBIS model for SN74LV244APWR and confirmed that the current is I_min=-103.74mA

Since the AMR for Input clamp current is max -20mA,

-103.74A<-20mA. So, the current also seems to be exceeding the rating.

[Questions]

1. Do you think this undershoot is not accepted for these two device?
2. Is there any criteria value for an acceptable undershoot/overshoot like "for pulse width lower than xx ns, exceeding under xx V is accepted"

Regards,

Ohashi