WM8978 Wolfson Microelectronics Ltd., WM8978 Datasheet - Page 28

• Manufacturer Part Number: WM8978
• Description: The WM8978 is a low power, high quality stereo codec designed for portable applications such as Digital still camera or Digital Camcorde
• Manufacturer: Wolfson Microelectronics Ltd.

WM8978
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The input PGAs are enabled by the IPPGAENL/R register bits.
Table 6 Input PGA Enable Register Settings
Table 7 Input PGA Control
INPUT PGA VOLUME CONTROLS
The input microphone PGAs have a gain range from -12dB to +35.25dB in 0.75dB steps. The gain
from the LIN/RIN input to the PGA output and from the L2/R2 amplifier to the PGA output are always
common and controlled by the register bits INPPGAVOLL/R[5:0]. These register bits also affect the
LIP pin when LIP2INPPGA=1, the L2 pin when L2_2INPPGA=1, the RIP pin when RIP2INPPGA=1
and the L2 pin when L2_2INPPGA=1.
When the Automatic Level Control (ALC) is enabled the input PGA gains are controlled
automatically and the INPPGAVOLL/R bits should not be used.
R2
Power
Management
2
R44
Input
Control
REGISTER
ADDRESS
REGISTER
ADDRESS
0
1
2
4
5
6
BIT
2
3
BIT
LIP2INPPGA
LIN2INPPGA
L2_2INPPGA
RIP2INPPGA
RIN2INPPGA
R2_2INPPGA
LABEL
INPPGAENL
INPPGAENR
LABEL
1
1
0
1
1
0
DEFAULT
0
0
DEFAULT
Connect LIP pin to left channel input PGA
amplifier positive terminal.
0 = LIP not connected to input PGA
1 = input PGA amplifier positive terminal
connected to LIP (constant input
impedance)
Connect LIN pin to left channel input PGA
negative terminal.
0=LIN not connected to input PGA
1=LIN connected to input PGA amplifier
negative terminal.
Connect L2 pin to left channel input PGA
positive terminal.
0=L2 not connected to input PGA
1=L2 connected to input PGA amplifier
positive terminal (constant input
impedance).
Connect RIP pin to right channel input
PGA amplifier positive terminal.
0 = RIP not connected to input PGA
1 = right channel input PGA amplifier
positive terminal connected to RIP
(constant input impedance)
Connect RIN pin to right channel input
PGA negative terminal.
0=RIN not connected to input PGA
1=RIN connected to right channel input
PGA amplifier negative terminal.
Connect R2 pin to right channel input PGA
positive terminal.
0=R2 not connected to input PGA
1=R2 connected to input PGA amplifier
positive terminal (constant input
impedance).
Left channel input PGA enable
0 = disabled
1 = enabled
Right channel input PGA enable
0 = disabled
1 = enabled
DESCRIPTION
PTD Rev 2.6 November 2005
DESCRIPTION
Preliminary Technical Data
28