Intel IXP46X, IXP45X manual 3.15.1De-CouplingCapacitance Recommendations, 3.15.2VCC De-Coupling

			Intel® IXP45X and Intel® IXP46X Product Line of Network Processors—General Hardware
			Design Considerations
Table 24.		Power Interface (Sheet 2 of 2)
	Name	Nominal	Description
		Voltage
			Supply voltage for internal logic of analog phase lock-loop circuitry. Requires special power filtering
VCCPLL1		1.3 V	circuitry. If operating at 667 MHz, this voltage must be increased to 1.5 V.
			See the Intel® IXP45X and Intel® IXP46X Product Line of Network Processors Datasheet.
			Supply voltage for internal logic of analog phase lock-loop circuitry. Requires special power filtering
VCCPLL2		1.3 V	circuitry. If operating at 667 MHz, this voltage must be increased to 1.5 V.
			See the Intel® IXP45X and Intel® IXP46X Product Line of Network Processors Datasheet.
			Supply voltage for internal logic of analog phase lock-loop circuitry. Requires special power filtering
VCCPLL3		1.3 V	circuitry. If operating at 667 MHz, this voltage must be increased to 1.5 V.
			See the Intel® IXP45X and Intel® IXP46X Product Line of Network Processors Datasheet.

3.15.1De-Coupling Capacitance Recommendations

It is common practice to place de-coupling capacitors between the supply voltages and ground. Placement can be near the input supply pins and ground, with one 100-nF capacitor per pin. Additional de-coupling capacitors can be place all over the board every 0.5” to 1.0”. This ensures good return path for currents and reduce power surges and high-frequency noise.

It is also recommended that 4.7-µF to 10-µF capacitors be placed every 2” to 3”.

3.15.2VCC De-Coupling

Connect one 100-nF capacitor per each VCC pin. Placement should be as close as possible to the pin. It is also recommended to place a 4.7-µF capacitor near the device.

Use traces as thick as possible to eliminate voltage drops in the connection.

3.15.3VCCP De-Coupling

Connect one 100-nF capacitor per each VCCP pin. Placement should be as close as possible to the pin. It is also recommended to place a 4.7-µF capacitor near the device.

Use traces as thick as possible to eliminate voltage drops in the connection.

3.15.4VCCM De-Coupling

Connect one 100-nF capacitor per each VCCM pin. Placement should be as close as possible to the pin. It is also recommended to place a 4.7-µF capacitor near the device.

Use traces as thick as possible to eliminate voltage drops in the connection.

3.15.5Power Sequence

Power sequence is crucial for proper functioning of the IXP45X/IXP46X network processors. For a complete description of power sequencing, see the Intel® IXP45X and Intel® IXP46X Product Line of Network Processors Datasheet.

3.15.6Reset Timing

Proper reset timing is also a crucial requirement for proper functioning of the IXP45X/ IXP46X network processors. There are two reset signal PWRON_RESET_N and RESET_IN_N which required assertion sequence.

Intel® IXP45X and Intel® IXP46X Product Line of Network Processors
HDD	February 2007
56	Document Number: 305261; Revision: 004