Part Number:SN74ALVCH16373
Hello. I have some questions regarding timing parameters for the SN74ALVCH16373. The timing requirements tW, tSU, tH refer to figure 1 in the datasheet. The input column in the figure table list Tr/Tf as </= 2.5ns. My questions are:
1) Is Tr/Tf measured at 10% to 90%, or is it 20% to 80%?
2) My Hyperlynx slow-weak corner simulations are reporting Tr = 5.35ns and Tf = 5.56ns on the D inputs. For LE inputs it is Tr = 1.7ns and Tf = 1.34ns. These measurements are using the 10/90 setting rather than the 20/80 setting in Hyperlynx. Figure 1 in the datasheet indicates tSU, tH, and tW are measured to Vm = 1.5V for the conditions Vcc = 3.3V and Tr/Tf </= 2.5ns. My question is, if Tr/Tf is > 2.5ns, does that mean we cannot use the Vm point for these measurement? Should we instead use the Vil and Vih points to measure the timing margins?
3) If we must use the Vil/ViH points for the D inputs since their Tr/Tf is > 2.5ns, does that mean we also need to use the Vil/Vih points on the LE input, or can we instead still measure to Vm on the LE input since its Tr/Tf is < 2.5ns?
Thanks,
Scott
