Pin Capacitance - Altera Cyclone IV Device Handbook

1–10
Example 1–1
3.0 V to 85°C at 3.15 V.
Example 1–1. Impedance Change
Because R
Because R

Pin Capacitance

Table 1–11
Table 1–11. Pin Capacitance for Cyclone IV Devices
Symbol
C Input capacitance on top and bottom I/O pins
IOTB
C Input capacitance on right I/O pins
IOLR
C Input capacitance on right I/O pins with dedicated LVDS output
LVDSLR
C Input capacitance on right dual
VREFLR
(2)
V or user I/O pin
REF
C Input capacitance on top and bottom dual
VREFTB
(2)
used as V or user I/O pin
REF
C Input capacitance on top and bottom dedicated clock input pins
CLKTB
C Input capacitance on right dedicated clock input pins
CLKLR
Notes to Table 1–11:
(1) The pin capacitance applies to FBGA, UBGA, and MBGA packages.
(2) When you use the VREF pin as a regular input or output, you can expect a reduced performance of toggle rate and t
capacitance.
(3) C for the EP4CE22 device is 30 pF.
VREFTB
Cyclone IV Device Handbook,
Volume 3
shows how to calculate the change of 50-I/O impedance from 25°C at
R
= (3.15 – 3) × 1000 × –0.026 = –3.83
V
R
= (85 – 25) × 0.262 = 15.72
T
is negative,
V
MF = 1 / (3.83/100 + 1) = 0.963
V
is positive,
T
MF = 15.72/100 + 1 = 1.157
T
MF = 0.963 × 1.157 = 1.114
= 50 × 1.114 = 55.71 
R
final
lists the pin capacitance for Cyclone IV devices.
(1)
Parameter
- purpose VREF pin when used as
- purpose VREF pin when
Chapter 1: Cyclone IV Device Datasheet
Operating Conditions
Typical – Typical – Typical –
Quad Flat Quad Flat Ball-Grid
Pack No Leads Array
(QFP) (QFN) (BGA)
7 7
7 7
8 8
21 21
(3)
23 23
7 7
6 6
because of higher pin
CO
December 2016 Altera Corporation
Unit
6 pF
5 pF
7 pF
21 pF
23 pF
6 pF
5 pF