Chapter 1: Cyclone III Device Data Sheet
1–9
Electrical Characteristics
Example 1–1 shows you the example to calculate the change of 50 Ω I/O impedance
from 25°C at 3.0 V to 85°C at 3.15 V:
Example 1–1.
ΔRV = (3.15 – 3) × 1000 × –0.026 = –3.83
ΔRT = (85 – 25) × 0.262 = 15.72
Because ΔRV is negative,
MFV = 1 / (3.83/100 + 1) = 0.963
Because ΔRT is positive,
MFT = 15.72/100 + 1 = 1.157
MF = 0.963 × 1.157 = 1.114
Rfinal = 50 × 1.114 = 55.71 Ω
Pin Capacitance
Table 1–9 lists the pin capacitance for Cyclone III devices.
Table 1–9. Cyclone III Devices Pin Capacitance
Typical – Typical –
Symbol
Parameter
Unit
QFP
FBGA
CIOTB
CIOLR
Input capacitance on top/bottom I/O pins
Input capacitance on left/right I/O pins
7
6
5
pF
pF
7
Input capacitance on left/right I/O pins with dedicated
LVDS output
CLV DSLR
8
21
7
21
pF
pF
pF
Input capacitance on left/right dual-purpose VREF pin
when used as VREF or user I/O pin
C
C
VREFLR (1)
VREFTB (1)
Input capacitance on top/bottom dual-purpose VREFpin
when used as VREF or user I/O pin
23 (2)
23 (2)
Input capacitance on top/bottom dedicated clock input
pins
CCLKTB
CCLKLR
7
6
6
5
pF
pF
Input capacitance on left/right dedicated clock input pins
Notes to Table 1–9:
(1) When VREF pin is used as regular input or output, a reduced performance of toggle rate and tCO is expected due to
higher pin capacitance.
(2) CVREFTB for EP3C25 is 30 pF.
© January 2010 Altera Corporation
Cyclone III Device Handbook, Volume 2
ALTERA [ ALTERA CORPORATION ]
