Manual

Stereo Audio Codec
with FLEXSOUND Technology
MAX98088
67
Line Inputs
The device includes two sets of line inputs (Figure 7).
Each set can be configured as a stereo single-ended
input or as a mono differential input. Each input includes
adjustable gain to match a wide range of input signal
levels. If a custom gain is needed, the external gain
mode provides a trimmed feedback resistor. Set the gain
by choosing the appropriate input resistor and using the
following formula:
AV
PGAIN
= 20 x log (20K/RIN)
The external gain mode also allows summing multiple
signals into a single input, by connecting multiple input
resistors as show in Figure 8, and inputting signals larger
than 1V
P-P
.
Table 3. Microphone Input Registers (continued)
Figure 7. Line Input Block Diagram
Figure 8. Summing Multiple Input Signals into INA/INB
REGISTER BIT NAME DESCRIPTION
0x4A
7 INABYP
INA_/EXTMIC_ to MIC1_ Bypass Switch
0 = Disabled
1 = Enabled
4 MIC2BYP
MIC1_ to MIC2_ Bypass Switch
0 = Disabled
1 = Enabled
1 RECBYP
See the Output Bypass Switches section.
0 SPKBYP
INADIFF
PGAINA:
+20dB TO -6dB
INABYP
INBDIFF
INA1/
EXTMICP
INA2/
EXTMICN
INB1
INB2
PGAINA:
+20dB TO -6dB
PGAINB:
+20dB TO -6dB
PGAINB:
+20dB TO -6dB
LEFT
INPUT 1
LEFT
INPUT 2
INA1/EXTMICP
VCM
INA2/EXTMICN
20kI
RIGHT
INPUT 1
RIGHT
INPUT 2
VCM
20kI