
Altera Corporation
4–33
June 2006
Stratix Device Handbook, Volume 2
Selectable I/O Standards in Stratix & Stratix GX Devices
The previous equation accounts for the input limitations, but you must
apply the appropriate equation from
Table 4–9 to determine the output
limitations.
When at least one additional output exists but no voltage referenced
inputs exist, apply the appropriate formula from
Table 4–10.When additional voltage referenced inputs and other outputs exist in the
same VREF bank, then the bidirectional pad limitation must again
simultaneously adhere to the input and output limitations. See the
following equation.
<Total number of bidirectional pads> + <Total number of input pads>
≤40 (20 on
each side of the VREF pad)
Table 4–9. Bidirectional pad Limitation Formulas (Where VREF Inputs Exist)
Package Type
Formula
Thermally enhanced FineLine BGA and
thermally enhanced BGA cavity up
<Total number of bidirectional pads>
≤20 (per VREF pad)
Non-thermally enhanced cavity up and
non-thermally enhanced FineLine BGA
<Total number of bidirectional pads>
≤15 (per VREF pad)
Table 4–10. Bidirectional Pad Limitation Formulas (Where VREF Outputs Exist)
Package Type
Formula
Thermally enhanced FineLine BGA and
thermally enhanced BGA cavity up
<Total number of bidirectional pads> + <Total number of additional
output pads> – <Total number of pads from the smallest group of pads
controlled by an OE>
≤20 (per VREF pad)
Non-thermally enhanced cavity up and
non-thermally enhanced FineLine BGA
<Total number of bidirectional pads> + <Total number of additional
output pads> – <Total number of pads from the smallest group of pads
controlled by an OE>
≤15 (per VREF pad)