WM8961 datasheet(46/116 Pages) WOLFSON

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WM8961

Pre-Production

PP, August 2009, Rev 3.1

HEADPHONE PLAYBACK MODES

Headphone playback can be optimised for lowest power or best SNR, depending on the application

requirements.

STANDARD MODE

Headphone playback with the best compromise between performance and power consumption can be

enabled using the default DAC to Headphone Playback power on sequence as implemented at control

write sequencer address 0, as detailed in “Control Write Sequencer”.

LOW POWER MODE

Headphone playback optimised for lower power consumption can be enabled. This results in a very

slight reduction in headphone driver performance.

The register setting listed in Table 32 can be added to the power up sequence in order to implement

this mode. Note that this register setting must take place before the charge pump is enabled. See the

“Charge Pump” section. If the write sequencer is used to configure the DAC to HP path, this register

write must take place before the write sequencer is enabled and triggered.

ADDRESS

BITS

LABEL

SETTING

DESCRIPTION

R82 (52h)

Charge

Pump B

1:0

CP_DYN_PWR[1:0]

Enable dynamic (Class W) power

saving

Table 32 Low Power Headphone Playback

SNR OPTIMISED MODE

Headphone playback optimised for best Signal to Noise Ratio (SNR) can be enabled, resulting in a

slight increase in power consumption.

The register settings listed in Table 33 can be added at the start of the power up sequence in order to

implement this mode. The LOUT1VOL and ROUT1VOL settings may require adjustment due to the

additional attenuation of HPL_VOL[2:0] and HPR_VOL[2:0].

To partly offset the increase in power consumption due to selecting “SNR Optimised mode”, it is

recommended to select Dynamic (Classs W) power saving) using CP_DYN_PWR=11. This saves

power but only slightly impacts THD + noise performance.

ADDRESS

BITS

LABEL

SETTING

DESCRIPTION

R30 (1Eh)

Clocking 3

MANUAL_MODE

Automatic configuration of system

clock dividers. Excludes master

mode audio interface clocks.

R6 (06h)

ADC & DAC

Control 2

DAC_OSR128

Automatically configure DACDIV[2:0]

for 128OSR mode. This will give a

SNR improvement at the expense of

power

R71 (47h)

Analogue HP 2

8:6

HPL_VOL[2:0]

000

Secondary HPL PGA Volume -7dB

5:3

HPR_VOL[2:0]

000

Secondary HPR PGA Volume -7dB

2:0

HP_BIAS_BOOST[2:0]

000

Boost bias into headphone driver x2

R68 (44h)

Analogue PGA

Bias

2:0

HP_PGAS_BIAS[2:0]

000

Headphone PGA bias x 2

R82 (52h) Charge

Pump B

1:0

CP_DYN_PWR[1:0]

Enable dynamic (Class W) power

saving

Table 33 Low Power Headphone Playback

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