CS47L35 datasheet(234/300 Pages) CIRRUS

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DS1085F3

CS47L35

5.1 Recommended External Components

Figure 5-10. Speaker Output Current Monitoring Connections (Speaker Protection)

5.1.6

Power Supply/Reference Decoupling

Electrical coupling exists particularly in digital logic systems where switching in one subsystem 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 that provides 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 CS47L35, 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.

PCB layout is also a contributory factor for coupling effects. If multiple power supply rails are connected to a single supply

source, it is recommended to provide separate PCB tracks connecting each rail to the supply. See Section 5.5 for

PCB-layout recommendations.

The recommended power-supply decoupling capacitors for CS47L35 are detailed in Table 5-1.

All decoupling capacitors should be placed as close as possible to the CS47L35 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 CS47L35.

Table 5-1. Power Supply Decoupling Capacitors

Power Supply

Decoupling Capacitor

AVDD1, AVDD2

2 x 1.0

F ceramic—one capacitor on each AVDDn pin

CPVDD1

4.7

F ceramic

CPVDD2

4.7

F ceramic

DBVDD1, DBVDD2

2 x 0.1

F ceramic 1—one capacitor on each DBVDDn pin

1.Total capacitance of 4.7

F is required for each DBVDDn domain. This can be provided by dedicated DBVDDn

decoupling or by other capacitors on the same power rail.

DCVDD

4.7

F ceramic

FLLVDD

1.0

F ceramic

MICVDD

4.7

F ceramic

SPKVDD

4.7

F ceramic

VREFC

2.2

F ceramic

SPKOUTP

SPKOUTN

IN2RP

IN2RN

SPKGNDP

SPKGNDN

0.1



(1%, 100ppm/°C)

CS47L35

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