WM9705SEFTSLASHV datasheet(21/55 Pages) WOLFSON

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WM9705

Production Data

PD Rev 4.4 August 2006

SPEN STATE AT

START-UP

CODEC ID (PIN 45 STRAPPING)

AUDIO DAC SLOT

DEFAULT

SPDIF OR I

DATASLOT DEFAULT

‘lo’ (rev2.2 compliant)

‘hi’ = ID = 0 = primary

Slots 3 and 4 - front channels

Slots 7 and 8

‘lo’ (rev2.2 compliant)

‘lo’ = ID = 1 = secondary

Slots 7 and 8 – surround

Slots 6 and 9

‘hi’ (WM proprietary)

‘hi’ = ID = 0 = primary

Slots 3 and 4 - front channels

Slots 3 and 4

‘hi’ (WM proprietary)

‘lo’ = ID = 1 = secondary

Slots 7 and 8 – surround

Slots 3 and 4

Table 2 DAC and SPDIF Slot Mapping Defaults

However, an exception to the rev2.2 mapping table is made when SPDIF operation is enabled

using the SPEN hardware enable pin (being held high at start-up): in this case SPDIF data is

immediately output from the DAC primary slots 3 and 4. This allows for driver-less SPDIF

operation, where the SPDIF or I

2S output is simply the data contained in the main audio DAC

channels. Channel status and control bits output along with the SPDIF data are as set in the

SPDIF control register 3Ah. If required SPDIF data channel slot mapping may be then changed

by setting SPSA bits as required. See tables 18, 19 and 20 for further details.

A mode is provided where the output from the ADC is sent out as the SPDIF or I

2S data as

above, rather than the data sent to the DACs over the AC link. This mode is enabled by setting bit

ADCO in register 5Ch. ADC data continues to be sent via the AC link to the controller as normal.

WM9705 supports SPDIF and I

2S data only at the default 48ks/s frame rate. Writing to SPSR bits

in register 3Ah any value other than the default 48ks/s rate will result in a fail to write, with the

48ks/s value being returned on subsequent reads of these values.

PRIMARY/SECONDARY ID SUPPORT

WM9705 supports operation as either a primary or a secondary codec. Configuration of the

device as either a primary or as a secondary, is selected by tying the CID0 pin 45 on the package.

Fundamentally, a device identified as a primary (ID = 0, CID0 = ‘hi’) produces BITCLK as an

output, whereas a secondary (any other ID) must be provided with BITCLK as an input. This has

the obvious implication that if the primary device on an AC link is disabled, the secondary devices

cannot function. The AC’97 Revision 2.2 specification defines that the CID0 pin has inverting

sense, and are provided with internal weak pull ups. Therefore, if no connections are made to the

CID0 pin, then the pin pull hi and an ID = 0 is selected, i.e. primary. External connect to ground

(with pull-down from 0 to 10k

Ω) will select codec ID = ‘1’.

PIN 45 CID0

SELECTED

PRIMARY OR

SECONDARY

BITCLK

NC or pull-up

Primary

Output

Ground

Secondary

Input

Table 3 Codec ID Selection

HEADPHONE DRIVE AND HEADSET AUTODETECT

Headphone drive capability is provided on the HPOUT output pins 39 and 41 (called AUXOUT in

AC’97 rev2.2 specification) and also on the MONOOUT output pin 37.

Headphones of impedance typically from 16

Ω upwards may be connected to these pins. AC

coupling with an appropriately sized capacitor is recommended for removal of the mid-rail DC

pedestal present on these outputs. AC’97 rev2.2 specification recommends 32

Ω headphones; if a

headphone is connected for use as a headset, where the stereo ear-pieces are driven in parallel,

then each capsule must be of minimum 32

Ω impedance.

In many applications it is desirable to be able to connect either a stereo headphone to the

headphone output pins, or a mono headset, comprising ear-piece(s) and a microphone. The

microphone signal is sent via the tip connected wire of the typical 3-wire jack. In this event it is

desirable to be able to auto-detect the connection of either the headphone or the headset (with

microphone). The main characteristic of the headset and microphone compared to the

headphone is that the microphone impedance is typically much higher than the headphone

capsule (assuming a typical moving coil headphone). Because of this it is possible to connect a

weak pull-up to the tip connection of the headphone jack.

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