WM8976CGEFLSLASHV datasheet(71/114 Pages) WOLFSON

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WM8976

PD, Rev 4.5, November 2011

AUDIO SAMPLE RATES

The WM8976 sample rates for the ADC and the DACs are set using the SR register bits. The cutoffs

for the digital filters and the ALC attack/decay times stated are determined using these values and

assume a 256fs master clock rate.

If a sample rate that is not explicitly supported by the SR register settings is required then the closest

SR value to that sample rate should be chosen, the filter characteristics and the ALC attack, decay

and hold times will scale appropriately.

ADDRESS

BIT

LABEL

DEFAULT

DESCRIPTION

Additional

Control

3:1

000

Approximate sample rate (configures the

coefficients for the internal digital filters):

000=48kHz

001=32kHz

010=24kHz

011=16kHz

100=12kHz

101=8kHz

110-111=reserved

Table 56 Sample Rate Control

MASTER CLOCK AND PHASE LOCKED LOOP (PLL)

The WM8976 has an on-chip phase-locked loop (PLL) circuit that can be used to:

Generate master clocks for the WM8976 audio functions from another external clock, e.g. in telecoms

applications.

Generate and output (on pin CSB/GPIO1 and/or GPI04) a clock for another part of the system that is

derived from an existing audio master clock.

Figure 40 shows the PLL and internal clocking arrangement on the WM8976.

The PLL can be enabled or disabled by the PLLEN register bit.

Note: In order to minimise current consumption, the PLL is disabled when the VMIDSEL[1:0] bits are

set to 00b. VMIDSEL[1:0] must be set to a value other than 00b to enable the PLL.

ADDRESS

BIT

LABEL

DEFAULT

DESCRIPTION

Power

management 1

PLLEN

PLL enable

0=PLL off

1=PLL on

Table 57 PLLEN Control Bit

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