WM9705 datasheet(33/55 Pages) WOLFSON

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WM9705

Production Data

PD Rev 4.4 August 2006

When the AC-link Codec Ready indicator bit (SDATAIN slot 0, bit 15) is a 1 it indicates that the

AC-link and the WM9705 control and status registers are in a fully operational state. The AC’97

controller must further probe this Powerdown Control/Status Register to determine exactly which

subsections, if any, are ready.

Note that the normal default condition of WM9705 when RESETB is applied is ‘all active’.

However, if pin MASK is pulled ‘hi’ during RESETB active, all PR bits are overridden and the

device enters a low power mode. This allows a low power standby mode to be entered without

writing to the device, a condition that is desirable for example, if batteries are changed in a PDA.

The state of the MASK pin is latched on the rising edge of RESETB and if MASK is ‘hi’ then the

WM9705 will remain in low power mode until register 26h is written to.

READ BIT

FUNCTION

REF

VREFs up to nominal level

ANL

Analogue mixers, etc ready

DAC

DAC section ready to accept data

ADC

ADC section ready to transmit data

Table 14 Powerdown Status Register Function

The Powerdown modes are as follows. The first three bits are to be used individually rather than

in combination with each other. The last bit PR3 can be used in combination with PR2 or by itself.

PR0 and PR1 control the PCM ADCs and DACs only. PR6 powers down just the stereo Line

Level output headphone amps on pins 39/41.

The WM9705 also includes a low power DAC to headphone mode, whereby resetting PR1and

PR6 enables the DAC and the path from the DAC to HPOUTL/R without having to power up the

main mixer (PR2). The POP bit (reg 20h) also needs to be set for this mode. The headphone

amplifier on the MONO output pin in not powered down by PR6, rather by PR2 or alternatively

may be enabled by setting MONOEN in register 74h.

WRITE BIT

FUNCTION

PR0

PCM in ADCs and input Mux Powerdown

PR1

PCM out DACs Powerdown

PR2

Analogue mixer Powerdown

(VREF still on)

PR3

Analogue mixer Powerdown (VREF off)

PR4

Digital interface (AC-link) Powerdown

(external clock off)

PR5

Internal clock disable

PR6

HP amp Powerdown

EAPD

External amplifier Powerdown

Table 15 Powerdown Control Register Function

PR0 = 1

PR1 = 1

PR2 = 1

PR4 = 1

PR0 = 0 AND

ADC = 1

DEFAULT

READY = 1

COLD RESET

WARM

RESET

PR2 = 0 AND

ANL = 1

PR1 = 0 AND

DAC = 1

ADCs OFF

PR0

DACs OFF

PR1

ANALOGUE

OFF PR2 OR

PR3

DIGITAL I/F

OFF PR4

SHUT OFF

CODA LINK

NORMAL

Figure 16 An Example of the WM9705 Powerdown/Powerup Flow

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