Production Data
WM8978
w
PD, Rev 4.5, October 2011
69
A dedicated buffer is available for tying off unused analogue I/O pins as shown in Figure 35. 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 35 summarises the tie-off options for the speaker and mono output pins.
Figure 35 Unused Input/Output Pin Tie-off Buffers
L/ROUT2EN/
OUT3/4EN
OUT3BOOST/
OUT4BOOST/
SPKBOOST
VROI OUTPUT
CONFIGURATION
0
0
0
1k
Ω
tie-off to AVDD/2
0
0
1
30k
Ω
tie-off to AVDD/2
0 1
0
1k
Ω
tie-off to 1.5xAVDD/2
0 1
1
30k
Ω
tie-off to 1.5xAVDD/2
1 0
X
Output enabled (DC level=AVDD/2)
1 1
X
Output enabled (DC level=1.5xAVDD/2)
Table 52 Unused Output Pin Tie-off Options
Summary of Contents for WM8978
Page 11: ...Production Data WM8978 w PD Rev 4 5 October 2011 11 SPEAKER OUTPUT THD VERSUS POWER...
Page 14: ...WM8978 Production Data w PD Rev 4 5 October 2011 14 AUDIO PATHS OVERVIEW...
Page 55: ...Production Data WM8978 w PD Rev 4 5 October 2011 55 Figure 26 Left Right Output Channel Mixers...
Page 60: ...WM8978 Production Data w PD Rev 4 5 October 2011 60 Figure 29 Speaker Outputs LOUT2 and ROUT2...