EP3C5E144C8N Datasheet, PDF (317/348 Pages) Altera Corporation – Ability to disable external JTAG port

Chapter 2: Cyclone III LS Device Data Sheet
2–3
Electrical Characteristics
1 A DC signal is equivalent to 100% of the duty cycle. For example, a signal that
overshoots to 4.2 V can only be at 4.2 V for 10.74% over the lifetime of the device; for a
device lifetime of 10 years, this is equivalent to 10.74% of ten years, which is 12.89
months.
Table 2–2. Cyclone III LS Devices Maximum Allowed Overshoot During Transitions over a 10-Year
Time Frame
Symbol Parameter
V_i
AC Input
Voltage
Condition
V_I = 3.95 V
V_I = 4.0 V
V_I = 4.05 V
V_I = 4.10 V
V_I = 4.15 V
V_I = 4.20 V
V_I = 4.25 V
V_I = 4.30 V
V_I = 4.35 V
V_I = 4.40 V
V_I = 4.45 V
V_I = 4.50 V
V_I = 4.60 V
V_I = 4.70 V
Overshoot Duration as % of High Time Unit
100
%
95.67
%
55.24
%
31.97
%
18.52
%
10.74
%
6.23
%
3.62
%
2.1
%
1.22
%
0.71
%
0.41
%
0.14
%
0.047
%
Figure 2–1 shows the methodology to determine the overshoot duration. In this
example, overshoot voltage is shown in red and is present on the input pin of the
Cyclone III LS device at over 4.1 V but below 4.2 V. From Table 2–1, for an overshoot
of 4.1 V, the percentage of high time for the overshoot can be as high as 31.97% over a
10-year period. Percentage of high time is calculated as ([delta T]/T) × 100. This
10-year period assumes the device is always turned on with 100% I/O toggle rate and
50% duty cycle signal. For lower I/O toggle rates and situations in which the device is
in an idle state, lifetimes are increased.
Figure 2–1. Cyclone III LS Devices Overshoot Duration
4.2 V
4.1 V
3.3 V
ΔT
T
December 2011 Altera Corporation
Cyclone III Device Handbook
Volume 2