HC4GX15 Datasheet, PDF (61/668 Pages) Altera Corporation – HardCopy IV Device Handbook

Chapter 6: HardCopy IV Device I/O Features
6–11
3.3- and 3.0-V I/O Interface
Table 6–5. HardCopy IV MultiVolt I/O Support (Part 2 of 2) (Note 1)
Input Signal (V)
Output Signal (V)
V_CCIO (V)
1.8
1.2 1.5 1.8 2.5 3.0 3.3 1.2 1.5 1.8 2.5 3.0 3.3
— v(2) v
—
—
—
—
—
v
—
—
—
2.5
— — — v v(2) v(2) — — — v — —
3.0
—
—
—
v
v v(2) —
—
—
—
v
—
3.3 (3)
—
—
—
—
—
—
—
—
—
—
—
—
Notes to Table 6–5:
(1) The 3.3-V I/O standard is supported using V_CCIO at 3.0 V.
(2) The pin current may be slightly higher than the default value. You must verify that the driving device's V_OL maximum and V_OH minimum voltages
do not violate the applicable HardCopy IV V_IL maximum and V_IH minimum voltage specifications.
(3) Use clamping diodes for all I/O pins when the input signal is 3.3 V. Altera recommends that you use an external clamping diode on the row I/O
pins when the input signal is 3.3 V. Refer to “3.3- and 3.0-V I/O Interface” for more information.
3.3- and 3.0-V I/O Interface
Similar to Stratix IV buffers, HardCopy IV I/O buffers support 3.3-V I/O standards.
You can use them as transmitters or receivers in your system. The output high voltage
(V_OH), output low voltage (V_OL), input high voltage (V_IH), and input low voltage (V_IL)
levels meet the 3.3-V I/O standards specifications defined by EIA/JEDEC Standard
JESD8-B with margin when the HardCopy IV V_CCIO voltage is powered by 3.0 V.
To ensure device reliability and proper operation when interfacing with a 3.3-V I/O
system using HardCopy IV devices, it is important to make sure that the absolute
maximum ratings of HardCopy IV devices are not violated.
1 Altera recommends performing IBIS simulation to determine that the overshoot and
undershoot voltages are within the guidelines.
When using the HardCopy IV device as a transmitter, some techniques can be used to
limit the overshoot and undershoot at the I/O pins, such as using slow slew rate and
series termination, but they are not required. Transmission line effects that cause large
voltage deviation at the receiver are associated with impedance mismatch between
the driver and transmission line. By matching the impedance of the driver to the
characteristic impedance of the transmission line, you can significantly reduce
overshoot voltage. You can use a series termination resistor placed physically close to
the driver to match the total driver impedance to transmission line impedance.
HardCopy IV devices support series on-chip termination (OCT) for all
LVTTL/LVCMOS I/O standards in all I/O banks.
When using the HardCopy IV device as a receiver, a technique you can use to limit the
overshoot, though not required, is using a clamping diode (on-chip or off-chip).
HardCopy IV devices provide an optional on-chip PCI clamping diode for column
I/O pins. You can use this diode to protect I/O pins against overshoot voltage.
The following features are identical to those in Stratix IV devices:
■ External memory interface
■ High-speed differential I/O with DPA support
■ Four levels of pre-emphasis for LVDS transmitters
■ Four levels of differential output voltage for LVDS transmitters
© January 2010 Altera Corporation
HardCopy IV Device Handbook, Volume 1