EP2C5T144I8N Datasheet, PDF (310/470 Pages) Altera Corporation – Cyclone II Device Handbook, Volume 1

Pad Placement and DC Guidelines
Differential Pad Placement Guidelines
To maintain an acceptable noise level on the V_CCIO supply, there are
restrictions on placement of single-ended I/O pads in relation to
differential pads in the same I/O bank. Use the following guidelines for
placing single-ended pads with respect to differential pads and for
differential output pads placement in Cyclone II devices.
For the LVDS I/O standard:
■ Single-ended inputs can be no closer than four pads away from an
LVDS I/O pad.
■ Single-ended outputs can be no closer than five pads away from an
LVDS I/O pad.
■ Maximum of four 155-MHz (or greater) LVDS output channels per
VCCIO and ground pair.
■ Maximum of three 311-MHz (or greater) LVDS output channels per
VCCIO and ground pair.
1 For optimal signal integrity at the LVDS input pad, Altera
recommends the LVDS, RSDS and mini-LVDS outputs are
placed five or more pads away from an LVDS input pad.
The Quartus II software only checks the first two cases.
For the RSDS and mini-LVDS I/O standards:
■ Single-ended inputs can be no closer than four pads away from an
RSDS and mini-LVDS output pad.
■ Single-ended outputs can be no closer than five pads away from an
RSDS and mini-LVDS output pad.
■ Maximum of three 85-MHz (or greater) RSDS and mini-LVDS output
channels per VCCIO and ground pair.
The Quartus II software only checks the first two cases.
For the LVPECL I/O standard:
■ Single-ended inputs can be no closer than four pads away from an
LVPECL input pad.
■ Single-ended outputs can be no closer than five pads away from an
LVPECL input pad.
1 For optimal signal integrity at the LVPECL input pad, Altera
recommends the LVDS, RSDS and mini-LVDS outputs are
placed five or more pads away from an LVPECL input pad.
10–28
Cyclone II Device Handbook, Volume 1
Altera Corporation
February 2008