Specifications

Guideline: Ensure Compatible V
CCIO
and V
CCPD
Voltage in the Same Bank
When planning I/O bank usage for Cyclone V devices, you must ensure the V
CCIO
voltage is compatible
with the V
CCPD
voltage of the same bank. Some banks may share the same V
CCPD
power pin. This limits the
possible V
CCIO
voltages that can be used on banks that share VCCPD power pins.
Examples:
•
VCCPD3B is connected to 2.5 V—VCCIO pins for banks 3B and 4A can be connected 1.2 V, 1.25 V,
1.35 V, 1.5 V, 1.8 V, or 2.5 V.
•
VCCPD3B is connected to 3.0 V—VCCIO pins for banks 3B and 4A must be connected to 3.0 V.
Guideline: VREF Pin Restrictions
For the Cyclone V devices, consider the following VREF pins guidelines:
•
You cannot assign shared VREF pins as LVDS or external memory interface pins.
•
SSTL, HSTL, and HSUL I/O standards do not support shared VREF pins. For example, if a particular
B1p or B1n pin is a shared VREF pin, the corresponding B1p/B1n pin pair do not have LVDS transmitter
support.
•
You must perform signal integrity analysis using your board design when using a shared VREF pin to
determine the F
MAX
for your system.
For more information about pin capacitance of the VREF pins, refer to the device datasheet.
Related Information
Cyclone V Device Datasheet
Guideline: Observe Device Absolute Maximum Rating for 3.3 V Interfacing
To ensure device reliability and proper operation when you use the device for 3.3 V I/O interfacing, do not
violate the absolute maximum ratings of the device. For more information about absolute maximum rating
and maximum allowed overshoot during transitions, refer to the device datasheet.
Perform IBIS or SPICE simulations to make sure the overshoot and undershoot voltages are within
the specifications.
Tip:
Transmitter Application
If you use the Cyclone V device as a transmitter, use slow slew-rate and series termination to limit the
overshoot and undershoot at the I/O pins. Transmission line effects that cause large voltage deviations at
the receiver are associated with an impedance mismatch between the driver and the transmission lines. 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 the transmission line impedance.
Receiver Application
If you use the Cyclone V device as a receiver, use the on-chip clamping diode to limit the overshoot and
undershoot voltage at the I/O pins.
Related Information
Cyclone V Device Datasheet
I/O Features in Cyclone V Devices
Altera Corporation
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CV-52005
Guideline: Ensure Compatible V
CCIO
and V
CCPD
Voltage in the Same Bank
5-18
2013.06.21