Chapter 6: I/O Features in the Cyclone III Device Family
6–3
I/O Element Features
Table 6–1 lists the possible settings for I/O standards with current strength control.
These programmable current strength settings are a valuable tool in helping decrease
the effects of simultaneously switching outputs (SSO) in conjunction with reducing
system noise. The supported settings ensure that the device driver meets the
specifications for IOHand IOLof the corresponding I/O standard.
1
When you use programmable current strength, on-chip series termination is not
available.
(1)
Table 6–1. Programmable Current Strength
IOH/IOL Current Strength Setting (mA)
I/O Standard
Top and Bottom I/O Pins
Left and Right I/O Pins
1.2-V LVCMOS
2, 4, 6, 8, 10,12
2, 4, 6, 8,10
1.5-V LVCMOS
2, 4, 6, 8, 10, 12,16
2, 4, 6, 8, 10, 12,16
1.8-V LVTTL/LVCMOS
2.5-V LVTTL/LVCMOS
3.0-V LVCMOS
2, 4, 6, 8, 10, 12,16
4, 8, 12,16
4, 8, 12,16
4, 8, 12,16
2
2, 4, 6, 8, 10, 12,16
4, 8, 12,16
4, 8, 12,16
4, 8, 12,16
2
3.0-V LVTTL
(2)
3.3-V LVCMOS
(2)
3.3-V LVTTL
4, 8
4, 8
HSTL-12 Class I
HSTL-12 Class II
HSTL-15 Class I
HSTL-15 Class II
HSTL-18 Class I
HSTL-18 Class II
SSTL-18 Class I
SSTL-18 Class II
SSTL-2 Class I
SSTL-2 Class II
BLVDS
8, 10,12
14
8, 10
—
8, 10, 12
16
8, 10, 12
16
8, 10, 12
16
8, 10, 12
16
8, 10, 12
12, 16
8, 10, 12
12, 16
8, 12
8, 12
16
16
8, 12, 16
8, 12, 16
Notes to Table 6–1:
(1) The default setting in the Quartus II software is 50-Ω OCT without calibration for all non-voltage reference and
HSTL/SSTL Class I I/O standards. The default setting is 25-Ω OCT without calibration for HSTL/SSTL Class II I/O
standards.
(2) The default current setting in the Quartus II software is highlighted in bold italic for 3.3-V LVTTL and 3.3-V LVCMOS
I/O standards.
f
For information about how to interface the Cyclone III device family with 3.3-, 3.0-, or
2.5-V systems, refer to the guidelines provided in AN 447: Interfacing Cyclone III and
Cyclone IV Devices with 3.3/3.0/2.5-V LVTTL/LVCMOS I/O Systems.
December 2011 Altera Corporation
Cyclone III Device Handbook
Volume 1
ALTERA [ ALTERA CORPORATION ]
