WM8941
Pre Production
WM8941 Video Buffer Filter Response
-20dBV sinewave input, 0dB gain setting, VBVDD=3.3V
10
5
0dB
0dB Qboost
6dB
6dB Qboost
0
-5
-10
-15
-20
-25
10
100
1000
10000
100000
Frequency (kHz)
Figure 26 WM8941 Video Buffer Filter Response
VIDEO BUFFER REGISTERS
Video buffer enable / disable and gain are controlled via the following registers:
REGISTER
ADDRESS
BIT
LABEL
VBUFEN
DEFAULT
DESCRIPTION
R3
4
0
Video buffer enable
0 = disabled
Power management 3
1 = enabled
R40
4
3
QBOOST
VBGAIN
0
0
Increases the filters Q.
Video Buffer
Video buffer gain
0 = 0dB (=6dB unloaded)
1 = +6dB (=12dB unloaded)
Disable Video Buffer DC Offset
2
1
VBDISOFF
0
0
0 = Video buffer drives down to
40mV above ground
1 = Video buffer drives to
ground (not recommended)
VBPULLDWN
Video Buffer Pull-down
0=Normal
1=Enables high impedance
pull-down on in put to Video
buffer
0
VBCLAMPEN
0
Video buffer clamp enable
0 = disabled
1 = enabled
Table 43 Video Buffer Registers
PP, Rev 3.3, December 2007
54
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WOLFSON [ WOLFSON MICROELECTRONICS PLC ]
