Specifications
ispGDX240VA
Figure 3. Adjacent I/O Cells vs. Direct Input Path for
ispGDX240VA, I/O D33
ispGDX240VA I/O Cell
I/O Group A
D31 MUX Out
I/O Group B
D32 MUX Out
I/O Group C
D34 MUX Out
I/O Group D
D35 MUX Out
4x4
Crossbar
Switch
S1 S0
.m0
.m1
.m2
.m3
Special Features
Slew Rate Control
All output buffers contain a programmable slew rate
control that provides software-selectable slew rate op-
tions.
Open Drain Control
D33
It can be seen from Figure 3 that if the D11 adjacent I/O
cell is used, the I/O group “A” input is no longer available
as a direct MUX input.
The ispGDXVA can implement MUXes up to 16 bits wide
in a single level of logic, but care must be taken when
combining adjacent I/O cell outputs with direct MUX
inputs. Any particular combination of adjacent I/O cells as
MUX inputs will dictate what I/O groups (A, B, C or D) can
be routed to the remaining inputs. By properly choosing
the adjacent I/O cells, all of the MUX inputs can be
utilized.
Table 2. Adjacent I/O Cells (Mapping of
ispGDX240VA)
Pull-up Resistor
All pins have a programmable active pull-up. A typical
resistor value for the pull-up ranges from 50kΩ to 80kΩ.
VA
B29
B30
B31
B32
D25
D26
D27
D28
D31
D32
D33
D34
B27
B28
B29
B30
B28
B29
B30
B31
D24
D25
D26
D27
D32
D33
D34
D35
B28
B29
B30
B31
Data A/ Data B/ Data C/ Data D/
MUXOUT MUXOUT MUXOUT MUXOUT
B30
B31
B32
Reflected
I/O Cells
B33
D26
D27
D28
D29
D30
D31
D32
Normal
I/O Cells
D33
B26
B27
B28
B29
B32
B33
B34
B35
D28
D29
D30
D31
D28
D29
D30
D31
B24
B25
B26
B27
D
B31
B32
B33
B34
D27
D28
D29
D30
D29
D30
D31
D32
B25
B26
B27
B28
A
N
5
C
Output Latch (Bus Hold)
All pins have a programmable circuit that weakly holds
the previously driven state when all drivers connected to
the pin (including the pin's output driver as well as any
other devices connected to the pin by external bus) are
tristated.
User-Programmable I/Os
The ispGDX240VA features user-programmable
I/Os supporting either 3.3V or 2.5V output voltage level
options. The ispGDX240VA uses a VCCIO pin to provide
the 2.5V reference voltage when used.
PCI Compatible Drive Capability
The ispGDX240VA supports PCI compatible drive capa-
bility for all I/Os.
ED
All output buffers provide a programmable Open-Drain
option which allows the user to drive system level reset,
interrupt and enable/disable lines directly without the
need for an off-chip Open-Drain or Open-Collector buffer.
Wire-OR logic functions can be performed at the printed
circuit board level.
LATTICE [ LATTICE SEMICONDUCTOR ]
