M1AFS250-FGG256I Actel Corporation, M1AFS250-FGG256I Datasheet - Page 169

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

Figure 2-110 • Timing Diagram (with skew circuit selected)
Weak Pull-Up and Weak Pull-Down Resistors
Fusion devices support optional weak pull-up and pull-down resistors for each I/O pin. When the I/O is
pulled up, it is connected to the V
connected to GND. Refer to
Slew Rate Control and Drive Strength
Fusion devices support output slew rate control: high and low. The high slew rate option is recommended
to minimize the propagation delay. This high-speed option may introduce noise into the system if
appropriate signal integrity measures are not adopted. Selecting a low slew rate reduces this kind of
noise but adds some delays in the system. Low slew rate is recommended when bus transients are
expected. Drive strength should also be selected according to the design requirements and noise
immunity of the system.
The output slew rate and multiple drive strength controls are available in LVTTL/LVCMOS 3.3 V,
LVCMOS 2.5 V, LVCMOS 2.5 V / 5.0 V input, LVCMOS 1.8 V, and LVCMOS 1.5 V. All other I/O
standards have a high output slew rate by default.
For Fusion slew rate and drive strength specifications, refer to the appropriate I/O bank table:
Table 2-80 on page 2-157
that are preset for each I/O standard.
Transmitter 1: OFF
Transmitter 2: ON
•
•
•
Fusion Standard I/O
Fusion Advanced I/O
Fusion Pro I/O
ENABLE (t2)
ENABLE (t1)
EN (b1)
EN (b2)
(Table 2-77 on page
lists the default values for the above selectable I/O attributes as well as those
(Table 2-75 on page
Table 2-94 on page 2-173
(Table 2-76 on page
CCI
Result: No Bus Contention
of its corresponding I/O bank. When it is pulled down, it is
2-154)
R e v i s i o n 1
Transmitter 1: ON
2-154)
2-154)
Transmitter 2: OFF
for more information.
Actel Fusion Family of Mixed Signal FPGAs
Transmitter 1: OFF
2- 153