M1A3P1000-1PQ208M Datasheet, PDF (168/212 Pages) Microsemi Corporation – Military ProASIC3/EL Low Power Flash FPGAs with Flash*Freeze Technology

Pin Descriptions and Packaging
JTAG Pins
Low power flash devices have a separate bank for the dedicated JTAG pins. The JTAG pins can be run
at any voltage from 1.5 V to 3.3 V (nominal). VCC must also be powered for the JTAG state machine to
operate, even if the device is in bypass mode; VJTAG alone is insufficient. Both VJTAG and VCC to the
part must be supplied to allow JTAG signals to transition the device. Isolating the JTAG power supply in a
separate I/O bank gives greater flexibility in supply selection and simplifies power supply and PCB
design. If the JTAG interface is neither used nor planned for use, the VJTAG pin together with the TRST
pin could be tied to GND.
TCK
Test Clock
Test clock input for JTAG boundary scan, ISP, and UJTAG. The TCK pin does not have an internal pull-
up/-down resistor. If JTAG is not used, Microsemi recommends tying off TCK to GND through a resistor
placed close to the FPGA pin. This prevents JTAG operation in case TMS enters an undesired state.
Note that to operate at all VJTAG voltages, 500  to 1 k will satisfy the requirements. Refer to Table 3-2
for more information.
Table 3-2 • Recommended Tie-Off Values for the TCK and TRST Pins
VJTAG
Tie-Off Resistance
VJTAG at 3.3 V
200  to 1 k
VJTAG at 2.5 V
200  to 1 k
VJTAG at 1.8 V
500  to 1 k
VJTAG at 1.5 V
500  to 1 k
Notes:
1. Equivalent parallel resistance if more than one device is on the JTAG chain
2. The TCK pin can be pulled up/down.
3. The TRST pin is pulled down.
TDI
Test Data Input
Serial input for JTAG boundary scan, ISP, and UJTAG usage. There is an internal weak pull-up resistor
on the TDI pin.
TDO
Test Data Output
Serial output for JTAG boundary scan, ISP, and UJTAG usage.
TMS
Test Mode Select
The TMS pin controls the use of the IEEE 1532 boundary scan pins (TCK, TDI, TDO, TRST). There is an
internal weak pull-up resistor on the TMS pin.
TRST
Boundary Scan Reset Pin
The TRST pin functions as an active low input to asynchronously initialize (or reset) the boundary scan
circuitry. There is an internal weak pull-up resistor on the TRST pin. If JTAG is not used, an external pull-
down resistor could be included to ensure the test access port (TAP) is held in reset mode. The resistor
values must be chosen from Table 3-2 and must satisfy the parallel resistance value requirement. The
values in Table 3-2 correspond to the resistor recommended when a single device is used, and the
equivalent parallel resistor when multiple devices are connected via a JTAG chain.
In critical applications, an upset in the JTAG circuit could allow entrance to an undesired JTAG state. In
such cases, Microsemi recommends tying off TRST to GND through a resistor placed close to the FPGA
pin.
Note that to operate at all VJTAG voltages, 500  to 1 k will satisfy the requirements.
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