Altera Early SSN Estimator - Manual (Page 8)

1–4 Chapter 1: Early SSN Estimator
Setting up the Early SSN Estimator
Early SSN Estimator User Guide for Altera Programmable Devices © November 2009 Altera Corporation
Figure 1–3 shows the ESE calculations for Bank1a when five I/Os are switching
simultaneously using LVTTL18 8-mA drive strength with a fast slew rate interface.
The example goes through the calculation to arrive at the V
IL
/V
IH
margin that is being
reported by the ESE tool.
1 Although each Altera device family has its own Early SSN tool, the methodology
behind these tools is the same. The following examples use the Stratix III Early SSN
tool.
From Figure 1–3 for the victim driven low, the various parameters are as follows:
K = 5
QLN (5) = 0.084 V
QL = 0
VIL max (DC) = 0.630 V
VIL margin (5) = {1 – [(0.084 – 0)/(0.63 – 0)]} * 100 = 86.7%
Similarly, for the victim driven high, the various parameters are as follows:
K = 5
QHN (5) = 1.723 V
QH = 1.8 V
VIH min (DC) = 1.17 V
VIH margin (5) = {1 – [(1.8 – 1.723)/ (1.8 – 1.17)]} * 100 = 87.8%
Figure 1–3. V
IL
/V
IH
Margin Calculation