afs600 Actel Corporation, afs600 Datasheet - Page 144

• Manufacturer Part Number: afs600
• Description: Actel Fusion Programmable System Chips Mixed-signal Family With Optional Arm Support
• Manufacturer: Actel Corporation

Solution 2
The board-level design must ensure that the reflected waveform at the pad does not exceed limits provided in
on page
This scheme will also work for a 3.3 V PCI/PCI-X configuration, but the internal diode should not be used for clamping,
and the voltage must be limited by the external resistors and Zener, as shown in
clamping would create an excessive pad DC voltage of 3.3 V + 0.7 V = 4 V.
Figure 2-96 • Solution 2
2 -1 3 0
Actel Fusion Programmable System Chips
3-4. This is a long-term reliability requirement.
5.5 V
Zener 3.3 V diode, LVCMOS 3.3 V I/Os
Rext1
Zener
3.3 V
Off-Chip
Requires one board resistor, one
Solution 2
A d v a n c e d v 1 . 4
On-Chip
Fusion I/O Input
3.3 V
Figure
2-96. Relying on the diode
Table 3-4