M1AFS250-FGG256I Actel Corporation, M1AFS250-FGG256I Datasheet - Page 164

• Manufacturer Part Number: M1AFS250-FGG256I
• Description: Actel Fusion Family Of Mixed Signal Fpgas
• Manufacturer: Actel Corporation

Device Architecture
2- 14 8
Solution 3
The board-level design must ensure that the reflected waveform at the pad does not exceed limits
provided in
This scheme will also work for a 3.3 V PCI/PCIX configuration, but the internal diode should not be used
for clamping, and the voltage must be limited by the bus switch, as shown in
diode clamping would create an excessive pad DC voltage of 3.3 V + 0.7 V = 4 V.
Figure 2-103 • Solution 3
Solution 4
Figure 2-104 • Solution 4
Table 3-4 on page
5.5 V
5.5 V
5.5 V
3-4. This is a long-term reliability requirement.
Bus
Switch
IDTQS32X23
Off-Chip
Rext1
Available for LVCMOS 2.5 V / 5.0 V.
Off-Chip
Requires one board resistor.
Requires a bus switch on the board,
LVTTL/LVCMOS 3.3 V I/Os.
R e visio n 1
Solution 4
Solution 3
On-Chip
On-Chip
Fusion I/O Input
Fusion I/O Input
2.5 V On-Chip
Clamp
Diode
3.3 V
2.5 V
Figure
2-103. Relying on the