SX-A Family FPGAs
Pin Description
CLKA/B, I/O
Clock A and B
PRA/B, I/O
Probe A/B
These pins are clock inputs for clock distribution
networks. Input levels are compatible with standard TTL,
LVTTL, LVCMOS2, 3.3 V PCI, or 5 V PCI specifications. The
clock input is buffered prior to clocking the R-cells. When
not used, this pin must be tied Low or High (NOT left
floating) on the board to avoid unwanted power
consumption.
For A54SX72A, these pins can also be configured as user
I/Os. When employed as user I/Os, these pins offer built-
in programmable pull-up or pull-down resistors active
during power-up only. When not used, these pins must
be tied Low or High (NOT left floating).
QCLKA/B/C/D, I/O
Quadrant Clock A, B, C, and D
The Probe pin is used to output data from any user-
defined design node within the device. This independent
diagnostic pin can be used in conjunction with the other
probe pin to allow real-time diagnostic output of any
signal path within the device. The Probe pin can be used
as a user-defined I/O when verification has been
completed. The pin’s probe capabilities can be
permanently disabled to protect programmed design
confidentiality.
TCK, I/O
Test Clock
These four pins are the quadrant clock inputs and are
only used for A54SX72A with A, B, C, and D
corresponding to bottom-left, bottom-right, top-left,
and top-right quadrants, respectively. They are clock
inputs for clock distribution networks. Input levels are
compatible with standard TTL, LVTTL, LVCMOS2, 3.3 V
PCI, or 5 V PCI specifications. Each of these clock inputs
can drive up to a quarter of the chip, or they can be
grouped together to drive multiple quadrants. The clock
input is buffered prior to clocking the R-cells. When not
used, these pins must be tied Low or High on the board
(NOT left floating).
These pins can also be configured as user I/Os. When
employed as user I/Os, these pins offer built-in
programmable pull-up or pull-down resistors active
during power-up only.
GND
HCLK
Ground
Dedicated (Hardwired)
Array Clock
Test clock input for diagnostic probe and device
programming. In Flexible mode, TCK becomes active
when the TMS pin is set Low (refer to
This pin functions as an I/O when the
boundary scan state machine reaches the "logic reset"
state.
TDI, I/O
Test Data Input
Serial input for boundary scan testing and diagnostic
probe. In Flexible mode, TDI is active when the TMS pin is
set Low (refer to
This pin
functions as an I/O when the boundary scan state
machine reaches the “logic reset” state.
TDO, I/O
Test Data Output
Serial output for boundary scan testing. In flexible mode,
TDO is active when the TMS pin is set Low (refer to
This pin functions as an I/O when
the boundary scan state machine reaches the "logic
reset" state. When Silicon Explorer II is being used, TDO
will act as an output when the checksum command is
run. It will return to user /IO when checksum is complete.
TMS
Test Mode Select
Low supply voltage.
This pin is the clock input for sequential modules. Input
levels are compatible with standard TTL, LVTTL,
LVCMOS2, 3.3 V PCI, or 5 V PCI specifications. This input is
directly wired to each R-cell and offers clock speeds
independent of the number of R-cells being driven.
When not used, HCLK must be tied Low or High on the
board (NOT left floating). When used, this pin should be
held Low or High during power-up to avoid unwanted
static power consumption.
I/O
Input/Output
The TMS pin controls the use of the IEEE 1149.1
Boundary Scan pins (TCK, TDI, TDO, TRST). In flexible
mode when the TMS pin is set Low, the TCK, TDI, and
TDO pins are boundary scan pins (refer to
Once the boundary scan pins are in test mode,
they will remain in that mode until the internal
boundary scan state machine reaches the logic reset
state. At this point, the boundary scan pins will be
released and will function as regular I/O pins. The logic
reset state is reached five TCK cycles after the TMS pin is
set High. In dedicated test mode, TMS functions as
specified in the IEEE 1149.1 specifications.
TRST, I/O
Boundary Scan Reset Pin
The I/O pin functions as an input, output, tristate, or
bidirectional buffer. Based on certain configurations,
input and output levels are compatible with standard
TTL, LVTTL, LVCMOS2, 3.3 V PCI or 5 V PCI specifications.
Unused I/O pins are automatically tristated by the
Designer software.
NC
No Connection
Once it is configured as the JTAG Reset pin, the TRST pin
functions as an active low input to asynchronously
initialize or reset the boundary scan circuit. The TRST pin
is equipped with an internal pull-up resistor. This pin
functions as an I/O when the
Reserve JTAG Reset Pin
is
not selected in Designer.
V
CCI
Supply Voltage
This pin is not connected to circuitry within the device
and can be driven to any voltage or be left floating with
no effect on the operation of the device.
Supply voltage for I/Os. See
All
V
CCI
power pins in the device should be connected.
V
CCA
Supply Voltage
Supply voltage for array. See
All
V
CCA
power pins in the device should be connected.
v5.3
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ACTEL [ Actel Corporation ]
