Pin Descriptions
10- 2
v1.1
VCOMPLA/B/C/D/E/F
PLL Ground
Ground to analog PLL power supplies. When the PLLs are not used, the Actel Designer place-and-
route tool automatically disables the unused PLLs to lower power consumption. The user should tie
unused VCCPLx and VCOMPLx pins to ground.
There is one VCOMPLF pin on IGLOO, ProASIC3L, and ProASIC3 devices.
There are six VCOMPL pins (PLL ground) on IGLOOe, ProASIC3EL, and ProASIC3E devices.
VJTAG
JTAG Supply Voltage
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). 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. It should be noted that VCC is required to be powered for JTAG operation; VJTAG
alone is insufficient. If a device is in a JTAG chain of interconnected boards, the board containing
the device can be powered down, provided both VJTAG and VCC to the part remain powered;
otherwise, JTAG signals will not be able to transition the device, even in bypass mode.
Actel recommends that VPUMP and VJTAG power supplies be kept separate with independent
filtering capacitors rather than supplying them from a common rail.
VPUMP
Programming Supply Voltage
IGLOO, ProASIC3L, and ProASIC3 devices support single-voltage ISP of the configuration flash and
FlashROM. For programming, VPUMP should be 3.3 V nominal. During normal device operation,
VPUMP can be left floating or can be tied (pulled up) to any voltage between 0 V and the VPUMP
maximum. Programming power supply voltage (VPUMP) range is listed in the datasheet.
When the VPUMP pin is tied to ground, it will shut off the charge pump circuitry, resulting in no
sources of oscillation from the charge pump circuitry.
For proper programming, 0.01 F and 0.33 F capacitors (both rated at 16 V) are to be connected in
parallel across VPUMP and GND, and positioned as close to the FPGA pins as possible.
Actel recommends that VPUMP and VJTAG power supplies be kept separate with independent
filtering capacitors rather than supplying them from a common rail.
User-Defined Supply Pins
VREF
I/O Voltage Reference
Reference voltage for I/O minibanks in IGLOOe, ProASIC3EL, and ProASIC3E devices. VREF pins are
configured by the user from regular I/Os, and any I/O in a bank, except JTAG I/Os, can be
designated the voltage reference I/O. Only certain I/O standards require a voltage reference—HSTL
(I) and (II), SSTL2 (I) and (II), SSTL3 (I) and (II), and GTL/GTL+. One VREF pin can support the number
of I/Os available in its minibank.