wm8961 Wolfson Microelectronics plc, wm8961 Datasheet - Page 46

• Manufacturer Part Number: wm8961
• Description: Ultra-low Power Stereo Codec With 1w Stereo Class D Speaker Drivers And Ground Referenced Headphone Drivers
• Manufacturer: Wolfson Microelectronics plc

HEADPHONE PLAYBACK MODES
w
WM8961
R82 (52h) Charge
R30 (1Eh)
Clocking 3
ADC & DAC
Control 2
R71 (47h)
R68 (44h)
Analogue PGA
Bias
Pump B
Analogue HP 2
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.
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.
Table 33 Low Power Headphone Playback
REGISTER
ADDRESS
R6 (06h)
REGISTER
ADDRESS
R82 (52h)
Pump B
Charge
BITS
1:0
BITS
0
0
8:6
5:3
2:0
2:0
1:0
CP_DYN_PWR[1:0]
MANUAL_MODE
DAC_OSR128
HPL_VOL[2:0]
HPR_VOL[2:0]
HP_BIAS_BOOST[2:0]
HP_PGAS_BIAS[2:0]
CP_DYN_PWR[1:0]
LABEL
LABEL
SETTING
SETTING
000
000
000
000
11
11
0
1
Enable dynamic (Class W) power
saving
Automatic configuration of system
clock dividers. Excludes master
mode audio interface clocks.
Automatically configure DACDIV[2:0]
for 128OSR mode. This will give a
SNR improvement at the expense of
power
Secondary HPL PGA Volume -7dB
Secondary HPR PGA Volume -7dB
Boost bias into headphone driver x2
Headphone PGA bias x 2
Enable dynamic (Class W) power
saving
DESCRIPTION
DESCRIPTION
PP, August 2009, Rev 3.1
Pre-Production
46