PCM1793

SLES076A − MARCH 2003 − REVISED JANUARY 2004

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CONSIDERATIONS FOR APPLICATION CIRCUITS

PCB Layout Guidelines

A typical PCB floor plan for the PCM1793 is shown in Figure 30. A ground plane is recommended, with the analog

and digital sections being isolated from one another using a split or cut in the circuit board. The PCM1793 must be

oriented with the digital I/O pins facing the ground plane split/cut to allow for short, direct connections to the digital

audio interface and control signals originating from the digital section of the board. Separate power supplies are

recommended for the digital and analog sections of the board. This prevents the switching noise present on the digital

supply from contaminating the analog power supply and degrading the dynamic performance of the D/A converters.

In cases where a common 5-V supply would be used for the analog and digital sections, an inductance (RF choke,

ferrite bead) must be placed between the analog and digital 5-V supply connections to avoid coupling of the digital

switching noise into the analog circuitry. Figure 31 shows the recommended approach for single-supply applications.

Digital Logic

and

Audio

Processor

Digital Power

+VD

DGND

Digital Section

Analog Section

Return Path for Digital Signals

Analog Power

+VS

AGND

−VS

+5VA

Digital

Ground

Analog

Ground

Output

Circuits

PCM1793

AGND

VCC

VDD

DGND

REG

Figure 30. Recommended PCB Layout