WM8731SEDSSLASHV datasheet(28/65 Pages) WOLFSON

28 / 65 page

WM8731 / WM8731L

Production Data

PD, Rev 4.9, October 2012

FROM DAC

DIGITAL

FILTERS

TO LINE OUTPUT

Figure 18 Multi-Bit Oversampling Sigma Delta Schematic

The DAC converts the multi-level digital audio data stream from the DAC digital filters into high quality

analogue audio.

LINE OUTPUTS

The WM8731/L provides two low impedance line outputs LLINEOUT and RLINEOUT, suitable for

driving typical line loads of impedance 10K and capacitance 50pF. The line output is used to

selectively sum the outputs from the DAC or/and the Line inputs in bypass mode.

The LLINEOUT and RLINEOUT outputs are only available at a line output level and are not level

adjustable in the analogue domain, having a fixed gain of 0dB. The level is fixed such that at the DAC

full scale level the output level is 1.0Vrms at AVDD = 3.3 volts. Note that the DAC full scale level

tracks directly with AVDD. The scheme is shown in Figure 19. The line output includes a low order

audio low pass filter for removing out-of band components from the sigma-delta DAC. Therefore no

further external filtering is required in most applications.

VMID

FROM LINE

INPUTS

LINEOUT

FROM DAC

BYPASS

TO HEADPHONE AMP

DACSEL

FROM MICROPHONE

INPUT

SIDETONE

Figure 19 Line Output Schematic

The DAC output, Line Input and microphone are summed into the Line Output. In DAC mode only the

output from the DAC is routed to the line outputs. In Bypass mode the Line Input is summed into the

Line Outputs. In Side Tone mode the Microphone Input is summed into the Line Output. These

features can be used for either over-dubbing or, if the DAC is muted, as a pure analogue bypass or

Side Tone feature, so avoiding any digital signal processing.

The line output is muted by either muting the DAC (analogue) or Soft Muting (digital) and disabling

the BYPASS and SIDETONE paths. Refer to the DAC section for more details. Whenever the DAC is

muted or the device placed into standby mode the DC voltage is maintained at the line outputs to

prevent any audible clicks from being present.

WM8731SEDS/V 数据表(PDF) 28 Page - Wolfson Microelectronics plc

WM8731SEDS/V 数据表(HTML) 28 Page - Wolfson Microelectronics plc

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65

数据表下载