EP2SGX30CF780C5N Datasheet, PDF (134/316 Pages) Altera Corporation – Section I. Stratix II GX Device Data Sheet

I/O Structure
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The bus-hold circuitry also pulls undriven pins away from the input
threshold voltage where noise can cause unintended high-frequency
switching. You can select this feature individually for each I/O pin. The
bus-hold output drives no higher than V_CCIO to prevent overdriving
signals. If the bus-hold feature is enabled, the programmable pull-up
option cannot be used. Disable the bus-hold feature when the I/O pin has
been configured for differential signals.
The bus-hold circuitry uses a resistor with a nominal resistance (RBH) of
approximately 7 kΩ to pull the signal level to the last-driven state.
Refer to the DC & Switching Characteristics chapter in volume 1 of the
Stratix II GX Device Handbook for the specific sustaining current driven
through this resistor and overdrive current used to identify the
next-driven input level. This information is provided for each V_CCIO
voltage level.
The bus-hold circuitry is active only after configuration. When going into
user mode, the bus-hold circuit captures the value on the pin present at
the end of configuration.
Programmable Pull-Up Resistor
Each Stratix II GX device I/O pin provides an optional programmable
pull-up resistor during user mode. If you enable this feature for an I/O
pin, the pull-up resistor (typically 25 kΩ ) holds the output to the V_CCIO
level of the output pin’s bank.
Programmable pull-up resistors are only supported on user I/O pins and
are not supported on dedicated configuration pins, JTAG pins, or
dedicated clock pins.
Advanced I/O Standard Support
The Stratix II GX device IOEs support the following I/O standards:
■ 3.3-V LVTTL/LVCMOS
■ 2.5-V LVTTL/LVCMOS
■ 1.8-V LVTTL/LVCMOS
■ 1.5-V LVCMOS
■ 3.3-V PCI
■ 3.3-V PCI-X mode 1
■ LVDS
■ LVPECL (on input and output clocks only)
■ Differential 1.5-V HSTL class I and II
■ Differential 1.8-V HSTL class I and II
■ Differential SSTL-18 class I and II
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Stratix II GX Device Handbook, Volume 1
Altera Corporation
October 2007