WM8351 datasheet(48/330 Pages) WOLFSON

48 / 330 page

WM8351

Production Data

PD, April 2012, Rev 4.5

When the GPIO5 pin is configured as CODEC_OPCLK, a clock derived from SYSCLK may be output

on this pin to provide clocking for other parts of the system. The frequency of this signal is set by

OPCLK_DIV.

Alternate GPIO pins can be used to provide ADCLRCLK and ADCBCLK as described in Section 20.

An inverted L/R clock signal ADCLRCLKB can also be generated. When this feature is used, the

LRCLK and BCLK pins support the DAC only, and the alternate GPIO pins support the ADC only.

Limited capability can be provided to support mixed sample rates by this method. (The selection of

USB mode and the supported values of the various SYSCLK dividers impose restrictions on what

combinations of clocking and sample rates may be configured.)

A slow clock derived from SYSCLK may be used to provide de-bouncing of the headphone detect

function, and to set the timeout period for volume updates when zero-cross functions are used. This

clock is enabled by TOCLK_ENA and its frequency is set by TOCLK_RATE.

The overall CODEC clocking scheme is illustrated in Figure 35.

MCLK

SYSCLK

ADC_CLKDIV[2:0]

R68[2:0]

1, 1.5, 2, 3, 4, 5.5, 6

DAC

LRCLK

(master mode output)

BCLK

(master mode output)

BCLKDIV[3:0]

R40[7:4]

1, 1.5, 2, 3, 4, 5.5, 6, 8,

11, 12, 16, 22, 24, 32

AIF_TRI

R112[13]

DAC_CLKDIV[2:0]

R54[2:0]

1, 1.5, 2, 3, 4, 5.5, 6

ADCLRCLK / CODEC_OPCLK

(GPIO5)

f/N

f/4

64fs

ADC

f/N

GP5_FN[3:0]

R141[7:4]

MCLK_DIV

R40[8]

1, 2

OPCLK_DIV[2:0]

R40[2:0]

1, 2, 3, 4, 5.5, 6

SLOWCLK

Jack detect debounce,

Volume update timeout

TOCLK_ENA

R40[15]

f/2

TOCLK_RATE

R40[14]

SYSCLK

All internal clocks are derived from SYSCLK, either directly

from MCLK or via the Frequency Locked Loop (FLL). The FLL

takes MCLK, ADCLRCLK, DACLRCLK or 32kHz input as its

reference.

ADC_CLKDIV

ADC sample rate is set by ADC_CLKDIV (Master or slave

mode).

DAC_CLKDIV

DAC sample rate is set by DAC_CLKDIV (Master or slave

mode).

BCLKDIV

BCLK rate is set by BCLKDIV in Master mode.

When ADC and DAC operate at different sample rates (in

master or slave mode), BCLK rate should be high enough to

support the higher of the ADC/DAC sample rates.

ADCLRCLK, ADCBCLK

These signals can be provided for the ADC via GPIO pins.

When these are used, the LRCLK and BCLK pins are used by

the DAC only.

OPCLK_DIV

GPIO Clock output frequency is set by OPCLK_DIV.

TOCLKSEL

A slow clock is used for jack detect debounce and for volume

update timeouts (when zero-crossing is enabled). The

frequency of this slow clock is set by TOCLK_RATE.

Other Sample Rate Controls

DEEMP configures the de-emphasis filter for the chosen

sample rate.

f/4

DACLRC_RATE[10:0]

R53[10:0]

1 .. 2047

ADCLRC_RATE[10:0]

R70[10:0]

1 .. 2047

ADCLRC_ENA

R70[11]

BCLK_MSTR

R115[14]

DACLRC_ENA

R53[11]

f/N

ADC_SYSCLK

DAC_SYSCLK

ADCBCLK

(GPIO8)

GP8_FN[3:0]

R142[3:0]

LRC_ADC_SEL

R41[15]

GP6_FN[3:0]

R141[11:8]

ADCLRCLKB

(GPIO6)

f/N

FLL

fREF

fOUT

DACLRCLK

ADCLRCLK

Crystal Oscillator /

GPIO 32kHz input

f/N

MCLK_SEL

R40[11]

FLL_CLK_SRC

R45[1:0]

Figure 35 Audio CODEC Clocking

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