WM5102 datasheet(320/334 Pages) WOLFSON

320 / 334 page

WM5102

Production Data

PD, June 2014, Rev 4.2

320

POWER SUPPLY / REFERENCE DECOUPLING

Electrical coupling exists particularly in digital logic systems where switching in one sub-system

causes fluctuations on the power supply. This effect occurs because the inductance of the power

supply acts in opposition to the changes in current flow that are caused by the logic switching. The

resultant variations (‘spikes’) in the power supply voltage can cause malfunctions and unintentional

behavior in other components. A decoupling (‘bypass’) capacitor can be used as an energy storage

component which will provide power to the decoupled circuit for the duration of these power supply

variations, protecting it from malfunctions that could otherwise arise.

Coupling also occurs in a lower frequency form when ripple is present on the power supply rail caused

by changes in the load current or by limitations of the power supply regulation method. In audio

components such as the WM5102, these variations can alter the performance of the signal path,

leading to degradation in signal quality. A decoupling capacitor can be used to filter these effects, by

presenting the ripple voltage with a low impedance path that does not affect the circuit to be

decoupled.

These coupling effects are addressed by placing a capacitor between the supply rail and the

corresponding ground reference. In the case of systems comprising multiple power supply rails,

decoupling should be provided on each rail.

The recommended power supply and voltage reference decoupling capacitors for WM5102 are

detailed below in Table 128.

POWER SUPPLY

DECOUPLING CAPACITOR

LDOVDD, DBVDD1, DBVDD2, DBVDD3, AVDD

0.1

F ceramic (see Note)

CPVDD

4.7

F ceramic

MICVDD

4.7

F ceramic

DCVDD

4.7

F ceramic

SPKVDDL, SPKVDDR

4.7

F ceramic

VREFC

1.0

F ceramic

Table 128 Power Supply Decoupling Capacitors

Note: 0.1

F is required with 4.7F a guide to the total required power rail capacitance.

All decoupling capacitors should be placed as close as possible to the WM5102 device. The

connection between AGND, the AVDD decoupling capacitor and the main system ground should be

made at a single point as close as possible to the AGND balls of the WM5102.

Due to the wide tolerance of many types of ceramic capacitors, care must be taken to ensure that the

selected components provide the required capacitance across the required temperature and voltage

ranges in the intended application. For most application the use of ceramic capacitors with capacitor

dielectric X5R is recommended.

WM5102 Datasheet(PDF) 320 Page - Wolfson Microelectronics plc

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