
IGLOO Low Power Flash FPGAs
Revision 23
3-3
When Flash*Freeze mode is used, the FF pin must not be left floating to avoid accidentally entering
Flash*Freeze mode. While in Flash*Freeze mode, the Flash*Freeze pin should be constantly asserted.
The Flash*Freeze pin can be used with any single-ended I/O standard supported by the I/O bank in
which the pin is located, and input signal levels compatible with the I/O standard selected. The FF pin
should be treated as a sensitive asynchronous signal. When defining pin placement and board layout,
simultaneously switching outputs (SSOs) and their effects on sensitive asynchronous pins must be
considered.
Unused FF or I/O pins are tristated with weak pull-up. This default configuration applies to both
Flash*Freeze mode and normal operation mode. No user intervention is required.
Table 3-1 shows the Flash*Freeze pin location on the available packages for IGLOO a devices. The
Flash*Freeze pin location is independent of device, allowing migration to larger or smaller IGLOO
devices while maintaining the same pin location on the board. Refer to the "Flash*Freeze Technology
states during Flash*Freeze mode.
Table 3-1 Flash*Freeze Pin Location in IGLOO Family Packages (device-independent)
IGLOO Packages
Flash*Freeze Pin
CS81/UC81
H2
CS121
J5
CS196
P3
CS281
W2
QN48
14
QN68
18
QN132
B12
VQ100
27
FG144
L3
FG256
T3
FG484
W6