WM8753LGEFLSLASHV datasheet(74/92 Pages) WOLFSON

74 / 92 page

Pre-Production

WM8753L

PP Rev 3.4 November 2005

SAVING POWER AT LOW SUPPLY VOLTAGES

The analogue supplies to the WM8753L can run from 1.8V to 3.6V. By default, all analogue circuitry

on the device is optimized to run at 3.3V. This set-up is also good for all other supply voltages down

to 1.8V. However, at lower voltages, it is possible to save power by reducing the internal bias currents

used in the analogue circuitry. This is controlled as shown below.

ADDRESS

BIT

LABEL

DEFAULT

DESCRIPTION

R18 (12h)

Additional

Control

7:6

VSEL

[1:0]

Analogue Bias optimization

00: Lowest bias current, optimized for AVDD=1.8V

01: Low bias current, optimized for AVDD=2.5V

1X: Default bias current, optimized for AVDD=3.3V

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 ADCOSR and DACOSR 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.

Important: ADC 64x mode is not available in USB mode (USB = 1). In USB mode ADCOSR

must be set to ‘0’.

ADDRESS

BIT

LABEL

DEFAULT

DESCRIPTION

VXDACOSR

Voice DAC oversample rate

select

1 = 64x (lowest power)

0 = 128x (best SNR)

ADCOSR

ADC oversample rate select

1 = 64x (lowest power)

0 = 128x (best SNR)

R7 (07h)

Sample Rate

Control (2)

DACOSR

DAC oversample rate select

1 = 64x (lowest power)

0 = 128x (best SNR)

Table 70 ADC and DAC Oversampling Rate Selection

SAVING POWER BY REDUCING BIAS CURRENTS

There are various biasing options within the WM8753L for increasing or reducing the bias current that

is used by sections of the chip.

The control of these is via the register bits MBIASBOOST,

VDACBIASX0P5,

MICBIASBST,

BUFBIAS,

IPBIASX0P5,

ADCBIAS,

OPBIASX0P5

and

DMBIASX0P5 as shown in Figure 31. The performance of the chip may vary when the bias currents

are changed from the default.

WM8753LGEFL/V Datasheet(PDF) 74 Page - Wolfson Microelectronics plc

WM8753LGEFL/V Datasheet(HTML) 74 Page - Wolfson Microelectronics plc

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