WM8758CBGEFLSLASHV datasheet(75/90 Pages) WOLFSON

75 / 90 page

Production Data

WM8758B

PD, Rev 4.4, January 2012

POWER SUPPLIES

The WM8758B requires four separate power supplies:



AVDD1 and AGND1: Analogue supply, powers all internal analogue functions and

output drivers LOUT1, ROUT1, OUT3 and OUT4. AVDD1 must be between 2.5V and

3.6V and has the most significant impact on overall power consumption (except for

power consumed in the headphones). Higher AVDD will improve audio quality.



AVDD2 and AGND2: Output driver supplies, power LOUT2 and ROUT2. AVDD2 must

be between 2.5V and 3.6V. AVDD2 can be tied to AVDD1, but it requires separate

layout and decoupling capacitors to curb harmonic distortion.



DCVDD: Digital core supply, powers all digital functions except the audio and control

interfaces. DCVDD must be between 1.71V and 3.6V, and has no effect on audio

quality. The return path for DCVDD is DGND, which is shared with DBVDD.



DBVDD must be between 1.71V and 3.6V. DBVDD return path is through DGND.

It is possible to use the same supply voltage for all four supplies. However, digital and analogue

supplies should be routed and decoupled separately on the PCB to keep digital switching noise out of

the analogue signal paths.

POWER MANAGEMENT

SAVING POWER BY REDUCING OVERSAMPLING RATE

The default mode of operation of the ADC and DAC digital filters is in 64x oversampling mode. Under

the control of ADCOSR128 the oversampling rate may be doubled. 64x oversampling results in a

slight decrease in noise performance compared to 128x but lowers the power consumption of the

device.

ADDRESS

BIT

LABEL

DEFAULT

DESCRIPTION

R14

ADC control

ADCOSR128

ADC oversample rate select

0 = 64x (lowest power)

1 = 128x (best SNR)

Table 53 ADC Oversampling Rate Selection

LOW POWER MODE

If only DAC or ADC functionality is required, the WM8758B can be put into a low power mode. In this

mode, the DSP core runs at half of the normal rate, reducing digital power consumption of the core

by half. For DAC low power only, 3D enhancement with 2-Band equalizer functionality is permitted,

where only Band 1 (low shelf) and Band 5 (high shelf) can be used. For ADC low power, the

equalizer and 3D cannot be used.

ADDRESS

BIT

LABEL

DEFAULT

DESCRIPTION

Additional Ctrl

M128ENB

0 = low power mode enabled

1 = low power mode disabled

Table 54 DSP Core Low Power Mode Control

WM8758CBGEFL/V Datasheet(PDF) 75 Page - Wolfson Microelectronics plc

WM8758CBGEFL/V Datasheet(HTML) 75 Page - Wolfson Microelectronics plc

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