Actel Fusion Mixed-Signal FPGAs
Pr el iminar y v1 .7
2- 139
Hot-Swap Support
Hot-swapping (also called hot plugging) is the operation of hot insertion or hot removal of a card
in (or from) a powered-up system. The levels of hot-swap support and examples of related
applications are described in
Table 2-71. The I/Os also need to be configured in hot insertion mode
if hot plugging compliance is required.
Table 2-71 Levels of Hot-Swap Support
Hot
Swapping
Level
Description
Power
Applied
to Device Bus State
Card
Ground
Connection
Device
Circuitry
Connected
to Bus Pins
Example of
Application with
Cards that Contain
Fusion Devices
Compliance of
Fusion Devices
1
Cold-swap
No
–
System and card
with Actel FPGA chip
are powered down,
then card gets
plugged into system,
then power supplies
are turned on for
system but not for
FPGA on card.
Compliant I/Os
can but do not
have to be set to
hot insertion
mode.
2
Hot-swap
while reset
Yes
Held in
reset state
Must be
made and
maintained
for 1 ms
before,
during, and
after
insertion/
removal
–
In PCI hot plug
specification, reset
control circuitry
isolates the card
busses until the card
supplies are at their
nominal operating
levels and stable.
Compliant I/Os
can but do not
have to be set to
hot insertion
mode.
3
Hot-swap
while bus
idle
Yes
Held idle
(no
ongoing
I/O
processes
during
insertion/re
moval)
Same as Level
2
Must
remain
glitch-free
during
power-up
or power-
down
Board bus shared
with card bus is
"frozen," and there
is no toggling
activity on bus. It is
critical that the logic
states set on the bus
signal do not get
disturbed during
card
insertion/removal.
Compliant with
cards with two
levels of
staging. I/Os
have to be set to
hot insertion
mode.
4
Hot-swap
on an active
bus
Yes
Bus may
have active
I/O
processes
ongoing,
but device
being
inserted or
removed
must be
idle.
Same as Level
2
Same as
Level 3
There is activity on
the system bus, and
it is critical that the
logic states set on
the bus signal do not
get disturbed during
card
insertion/removal.
Compliant with
cards with two
levels of
staging. I/Os
have to be set to
hot insertion
mode.