WM8591GEDSSLASHRV datasheet(15/51 Pages) WOLFSON

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Production Data

WM8591

PD Rev 4.0 December 2005

ADCBCLK and DACBCLK are also generated by the WM8591. The frequency of ADCBCLK and

DACBCLK can be set in software.

BCLK can be set to MCLK/4, 64fs or 128fs. If DSP mode is selected as the audio interface mode

then BCLK can be set to MCLK, 64fs or 128fs. Note that DSP mode cannot be used in 128fs mode

for word lengths greater than 16 bits or in 192fs mode for word lengths greater than 24 bits.

ZERO DETECT

The WM8591 has a zero detect circuit for each DAC channel, which detects when 1024 consecutive

zero samples have been input. The two zero flag outputs (ZFLAGL and ZFLAGR) may be

programmed to output the zero detect signals (see Table 9) that may then be used to control external

muting circuits.

The ZFLAGL and ZFLAGR pins require a pull-up resistor to be connected (see

external components diagram). The ZFLAGL and ZFLAGR pads will pull low to indicate that the zero

condition has been detected.

The polarity of the zero flag signals can be changed by setting the ZFLAGPOL bit. When this bit is

set, the ZFLAGL and ZFLAGR pins will pull low when the zero condition is not found and will go to

high impedance when the zero condition is detected.

The zero detect may also be used to automatically enable the mute by setting IZD. The zero flag

output may be disabled by setting DZFM to 00.

Table 9 Zero Flag Control

POWERDOWN MODES

The WM8591 has powerdown control bits allowing specific parts of the WM8591 to be powered off

when not being used. Control bit ADCPD powers off the ADC. The stereo DAC has a separate

powerdown control bit, DACPD allowing the DAC to be powered off when not in use.

Setting ADCPD and DACPD will powerdown everything except the references VMID, REFN and

REFP. Setting PDWN will override all other powerdown control bits. It is recommended that ADCPD

and DACPD are set before setting PDWN. The default is for all blocks to be enabled.

BIT

LABEL

DEFAULT

DESCRIPTION

Sets ADCBCLK and DACBCLK rate in master mode

BCLK_RATE

BCLK Output Frequency

MCLK/4 (MCLK in DSP Mode)

64fs

R28 (1Ch)

0011100

ADC/DAC Synchronization

3:2

BCLK_RATE

128fs

BIT

LABEL

DEFAULT

DESCRIPTION

ZFLAG decode

DZFM

ZFLAGL

ZFLAGR

Zero flag disabled

Left channel zero

Right channel zero

Both channel zero

2:1

DZFM

Either channels zero

Either channel zero

ZFLAG polarity

ZFLAGPOL

ZFLAGL

ZFLAGR

Pin pulls low to indicate zero conidition,

high impedance otherwise

R9 (09h)

0001001

DAC Mute

ZFLAGPOL

Pin is high impedance when zero

condition detected, pulls low otherwise

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