wm8770 Wolfson Microelectronics plc, wm8770 Datasheet - Page 50

• Manufacturer Part Number: wm8770
• Description: 24-bit, 192khz 8-channel Codec With Volume Control
• Manufacturer: Wolfson Microelectronics plc

WM8770
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It is recommended that a lowpass filter be applied to the output from each DAC channel for Hi Fi
applications. Typically a second order filter is suitable and provides sufficient attenuation of high
frequency components (the unique low order, high bit count multi-bit sigma delta DAC structure used
in WM8770 produces much less high frequency output noise than competitors devices). This filter is
typically also used to provide the 2x gain needed to provide the standard 2Vrms output level from
most consumer equipment. Figure 24 shows a suitable post DAC filter circuit, with 2x gain.
Alternative inverting filter architectures might also be used with as good results.
Figure 41 Recommended Post DAC Filter Circuit
VOUT1R
VOUT2R
VOUT3R
VOUT4R
VOUT1L
VOUT2L
VOUT3L
VOUT4L
10uF
47kΩ
1.8kΩ
680pF
7.5kΩ
OP_FIL
OP_FIL
OP_FIL
OP_FIL
OP_FIL
OP_FIL
OP_FIL
1.0nF
4.7kΩ
4.7kΩ
OP_FIL
51
PD Rev 4.2 March 2008
Production Data
50