1–8
Chapter 1: Cyclone III Device Datasheet
Electrical Characteristics
Example 1–1 shows you the example to calculate the change of 50 I/O impedance
from 25°C at 3.0 V to 85°C at 3.15 V:
Example 1–1.
RV = (3.15 – 3) × 1000 × –0.026 = –3.83
RT = (85 – 25) × 0.262 = 15.72
Because RV is negative,
MFV = 1 / (3.83/100 + 1) = 0.963
Because RT is positive,
MFT = 15.72/100 + 1 = 1.157
MF = 0.963 × 1.157 = 1.114
R
final = 50 × 1.114 = 55.71
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
CLVDSLR
8
7
pF
pF
pF
CVREFLR
Input capacitance on left/right dual-purpose VREF pin
when used as VREF or user I/O pin
21
21
(1)
CVREFTB
Input capacitance on top/bottom dual-purpose VREF pin
when used as VREF or user I/O pin
(2)
(2)
23
23
(1)
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.
Cyclone III Device Handbook
Volume 2
July 2012 Altera Corporation
ALTERA [ ALTERA CORPORATION ]
