CS8920 datasheet(20/66 Pages) CIRRUS

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AN84REV1

CS8920 Technical Reference Manual

2.2 Layout considerations for the

CS8920

The CS8920 is a mixed signal device

having digital and analog circuits for an

Ethernet communication. While doing the

PCB layout and signal connections, it is

important to take the following precautions:

(a) Provide a low inductive path to

reduce power and ground

connection noise.

(b) Provide proper impedance

matching especially to the Ethernet

analog signals.

and short traces, for all analog

signals.

It is important that a PCB designer follow

suggestions made in this document for

proper and reliable operation of the

CS8920. These guidelines will also help to

ensure good EMI test results.

2.2.1 General guidelines

Figure 2.2.1 shows component placement

for an ISA COMBO Ethernet adapter card

using a CS8900. For a CS8920 Combo

card, substitute CS8920 in place of

CS8900. The placement of the CS8920

should be such that the routes of the analog

signals and the digital signals are not

intermixing. No signal should route

beneath the CS8920 on any plane.

2.2.2 Power supply connections

The CS8920 has 3 analog and 5 digital

power pin pairs (Vcc and GND).

Additional ground connections are

provided. Each power pin pair should be

connected to a 0.1

µF bypass capacitor.

Connect the extra ground pins directly to

the ground plane.

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