I/O Termination
The majority of the Cyclone II I/O standards are single-ended,
non-voltage-referenced I/O standards and, as such, the following I/O
standards do not specify a recommended termination scheme:
I/O Termination
■
■
■
■
■
3.3-V LVTTL and LVCMOS
2.5-V LVTTL and LVCMOS
1.8-V LVTTL and LVCMOS
1.5-V LVCMOS
3.3-V PCI and PCI-X
Voltage-Referenced I/O Standard Termination
Voltage-referenced I/O standards require both an input reference
voltage, VREF, and a termination voltage, VTT. The reference voltage of the
receiving device tracks the termination voltage of the transmitting device.
For more information on termination for voltage-referenced I/O
standards, refer to “Supported I/O Standards” on page 10–1.
Differential I/O Standard Termination
Differential I/O standards typically require a termination resistor
between the two signals at the receiver. The termination resistor must
match the differential load impedance of the bus.
Cyclone II devices support differential I/O standards LVDS, RSDS, and
mini-LVDS, and differential LVPECL.
For more information on termination for differential I/O standards, refer
to “Supported I/O Standards” on page 10–1.
10–26
Altera Corporation
Cyclone II Device Handbook, Volume 1
February 2008
ALTERA [ ALTERA CORPORATION ]
