ep3c120f780c8nes Altera Corporation, ep3c120f780c8nes Datasheet - Page 148

• Manufacturer Part Number: ep3c120f780c8nes
• Description: Cyclone Iii Device Family
• Manufacturer: Altera Corporation

Clock Networks and PLLs in Cyclone III Devices
6–48
Cyclone III Device Handbook, Volume 1
VCCD and GND
The digital power and ground pins are labeled VCCD_PLL<PLL number>
and GND. The VCCD pin supplies the power for the digital circuitry in the
PLL. Connect these VCCD pins to the quietest digital supply on the board.
In most systems, this is the digital 1.2-V supply supplied to the device's
VCCINT pins. Connect the VCCD pins to apower supply even if you do not
use the PLL. You can connect the GND pins directly to the same ground
plane as the device's digital ground.
You should filter each VCCA and VCCD pin with a decoupling circuit
shown in
frequencies of 50 MHz or higher and a 10μF tantalum parallel capacitor
where the power enters the board. Decouple each VCCA pin with a 0.1μF,
0.001μF, 1μF, 47μF and 470μF parallel combination of ceramic capacitors
located as close as possible to the Cyclone III device. You can connect the
GNDA pins directly to the same ground plane as the device's digital
ground.
Figure
6–27. Place a ferrite bead that exhibits high impedance at
Altera Corporation- Preliminary
March 2007