WM8734 ETC-unknow, WM8734 Datasheet - Page 17

• Manufacturer Part Number: WM8734
• Description: Stereo Audio Codec
• Manufacturer: ETC-unknow

WM8734
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LINE OUTPUTS
The WM8734 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 Vrms at AVDD = 3.3 volts. Note that the DAC full scale level tracks
directly with AVDD. The scheme is shown in Figure 14. 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.
Figure 14 Line Output Schematic
The line output is muted by either muting the DAC (analogue) or Soft Muting (digital). 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.
The software control for the line outputs is shown in Table 4.
Table 4 Output Software Control
The recommended external components are shown in Figure 15.
0000100
Analogue
Audio Path
Control
REGISTER
ADDRESS
LINEOUT
FROM DAC
BIT
4
DACSEL
LABEL
C1
DACSEL
AGND
VMID
DEFAULT
0
R1
R2
DAC Select
1 = Select DAC
0 = Don’t select DAC
AI Rev 2.2 November 2001
DESCRIPTION
Advanced Information
AGND
TO HEADPHONE AMP
LINEOUT
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