CS4812 datasheet(28/36 Pages) CIRRUS

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CS4812

DS291PP3

4. POWER SUPPLY AND GROUNDING

Proper layout and grounding is critical to obtaining

optimal audio performance in your system. The

most important rule to remember is to not allow

currents from digital circuitry to couple into sensi-

tive analog circuitry. This is generally done by us-

ing a separate or filtered power supply for the

analog circuitry, physically separating the analog

and digital components and traces in the pcb layout

and using wide traces or planes for ground and

power. One misplaced component or trace can se-

verely degrade overall system performance.

When using separate supplies, the analog and digi-

tal power should be connected to the CS4812 via a

ferrite bead, positioned closer than 1" to the device

(see Figure 21). The CS4812 VA pin should be de-

rived from the quietest power source available. If

only one supply is available, use the suggested ar-

rangement in Figure 5.

A single solid ground plane is the simplest ground-

ing scheme that works well in many cases. All an-

alog and digital grounds shown in Figure 5 should

be tied to the one plane.

Decoupling capacitors should be placed as close as

possible to the device with the lowest value capac-

itor closest to the chip. Any power and ground con-

nection vias should be placed near their respective

component pins and should be attached directly to

the appropriate plane. If traces are used for the

power supplies to the CS4812, they should be as

wide as possible to maintain low impedance.

It is recommended to solder the CS4812 directly to

the printed circuit board. Soldering improves per-

formance and enhances reliability

Digital

Power

Plane

Note that the CS4812

is oriented with its

digital pins towards the

digital end of the board.

Digital Interface

Analog Signals &

Components

Analog

Power

Plane

1/8"

CS4812

Ferrite

Bead

Figure 27. CS4812 Suggested Layout

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