5–4
Altera Corporation
Stratix Device Handbook, Volume 2
July 2005
Stratix I/O Banks
LVDS
The LVDS I/O standard is a differential high-speed, low-voltage swing,
low-power, general-purpose I/O interface standard requiring a 3.3-V
VCCIO. This standard is used in applications requiring high-bandwidth
data transfer, backplane drivers, and clock distribution. The
ANSI/TIA/EIA-644 standard specifies LVDS transmitters and receivers
capable of operating at recommended maximum data signaling rates of
655 Mbps. However, devices can operate at slower speeds if needed, and
there is a theoretical maximum of 1.923 Gbps. Stratix devices meet the
ANSI/TIA/EIA-644 standard.
Due to the low voltage swing of the LVDS I/O standard, the
electromagnetic interference (EMI) effects are much smaller than CMOS,
transistor-to-transistor logic (TTL), and PECL. This low EMI makes LVDS
ideal for applications with low EMI requirements or noise immunity
requirements. The LVDS standard specifies a differential output voltage
range of 0.25 V
× VOD ≤0.45 V. The LVDS standard does not require an
input reference voltage, however, it does require a 100-
Ωtermination
resistor between the two signals at the input buffer. Stratix devices
include an optional differential termination resistor within the device. See
HyperTransport Technology
The HyperTransport technology I/O standard is a differential high-
speed, high-performance I/O interface standard requiring a 2.5-V
VCCIO. This standard is used in applications such as high-performance
networking, telecommunications, embedded systems, consumer
electronics, and Internet connectivity devices. The HyperTransport
technology I/O standard is a point-to-point standard in which each
HyperTransport technology bus consists of two point-to-point
unidirectional links. Each link is 2 to 32 bits. See the Stratix Device Family
Data Sheet section of the Stratix Device Handbook, Volume 1 for the
HyperTransport parameters.
LVPECL
The LVPECL I/O standard is a differential interface standard requiring a
3.3-V VCCIO. The standard is used in applications involving video
graphics, telecommunications, data communications, and clock
distribution. The high-speed, low-voltage swing LVPECL I/O standard
uses a positive power supply and is similar to LVDS, however, LVPECL
has a larger differential output voltage swing than LVDS. See the Stratix
Device Family Data Sheet section of the Stratix Device Handbook, Volume 1
for the LVPECL signaling characteristics.