WM8978 Datasheet, PDF (51/78 Pages) Wolfson Microelectronics plc – STEREO CODEC WITH SPEAKER DRIVER

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WM8978
A dedicated buffer is available for tying off unused analogue I/O pins as shown in Figure 22. This
buffer can be enabled using the BUFIOEN register bit.
If the SPKBOOST, OUT3BOOST or OUT4BOOST bits are set then the relevant outputs will be tied
to the output of the DC level shift buffer at 1.5xAVDD/2 when disabled.
Figure 22 summarises the tie-off options for the speaker and mono output pins.
Figure 22 Unused Input/Output Pin Tie-off Buffers
L/ROUT2EN/
OUT3/4EN
OUT3BOOST/
OUT4BOOST/
VROI
SPKBOOST
0
0
0
0
0
1
0
1
0
0
1
1
1
0
X
1
1
X
Table 43 Unused Output Pin Tie-off Options
OUTPUT CONFIGURATION
1kΩ tie-off to AVDD/2
30kΩ tie-off to AVDD/2
1kΩ tie-off to 1.5xAVDD/2
30kΩ tie-off to 1.5xAVDD/2
Output enabled (DC level=AVDD/2)
Output enabled (DC level=1.5xAVDD/2)
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PP Rev 1.7 January 2005
51