Fusion Family of Mixed Signal FPGAs
Revision 4
2-227
VCCOSC
Oscillator Power Supply (3.3 V)
Power supply for both integrated RC oscillator and crystal oscillator circuit. The internal 100 MHz
oscillator, powered by the VCCOSC pin, is needed for device programming, operation of the VDDN33
pump, and eNVM operation. VCCOSC is off only when VCCA is off. VCCOSC must be powered
whenever the Fusion device needs to function.
VCC
Core Supply Voltage
Supply voltage to the FPGA core, nominally 1.5 V. VCC is also required for powering the JTAG state
machine, in addition to VJTAG. Even when a Fusion device is in bypass mode in a JTAG chain of
interconnected devices, both VCC and VJTAG must remain powered to allow JTAG signals to pass
through the Fusion device.
VCCIBx
I/O Supply Voltage
Supply voltage to the bank's I/O output buffers and I/O logic. Bx is the I/O bank number. There are either
four (AFS090 and AFS250) or five (AFS600 and AFS1500) I/O banks on the Fusion devices plus a
dedicated VJTAG bank.
Each bank can have a separate VCCI connection. All I/Os in a bank will run off the same VCCIBx supply.
VCCI can be 1.5 V, 1.8 V, 2.5 V, or 3.3 V, nominal voltage. Unused I/O banks should have their
corresponding VCCI pins tied to GND.
VCCPLA/B
PLL Supply Voltage
Supply voltage to analog PLL, nominally 1.5 V, where A and B refer to the PLL. AFS090 and AFS250
each have a single PLL. The AFS600 and AFS1500 devices each have two PLLs. Microsemi
recommends tying VCCPLX to VCC and using proper filtering circuits to decouple VCC noise from PLL.
If unused, VCCPLA/B should be tied to GND.
VCOMPLA/B
Ground for West and East PLL
VCOMPLA is the ground of the west PLL (CCC location F) and VCOMPLB is the ground of the east PLL
(CCC location C).
VJTAG
JTAG Supply Voltage
Fusion 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 to be used, 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
Fusion device is in a JTAG chain of interconnected boards and it is desired to power down the board
containing the Fusion device, this may be done provided both VJTAG and VCC to the Fusion part remain
powered; otherwise, JTAG signals will not be able to transition the Fusion device, even in bypass mode.
VPUMP
Programming Supply Voltage
Fusion devices support single-voltage ISP programming of the configuration flash and FlashROM. For
programming, VPUMP should be in the 3.3 V +/-5% range. During normal device operation, VPUMP can
be left floating or can be tied to any voltage between 0 V and 3.6 V.
When the VPUMP pin is tied to ground, it shuts 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.