CS4812 Cirrus Logic, CS4812 Datasheet - Page 28

• Manufacturer Part Number: CS4812
• Description: Fixed Function Multi-Effects Audio Processor
• Manufacturer: Cirrus Logic

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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
28
Digital
Power
Plane
Digital Interface
Figure 27. CS4812 Suggested Layout
>
1/8"
CS4812
Analog Signals &
Components
Ferrite
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
Bead
Analog
Power
Plane
Note that the CS4812
is oriented with its
digital pins towards the
digital end of the board.
CS4812
DS291PP3