Datasheet

LM49370
SNAS356D –FEBRUARY 2007–REVISED MARCH 2012 www.ti.com
SIDETONE ATTENUATION REGISTER
This register is used to control the analog sidetone attenuation.
(1)
Table 20. SIDETONE (0x0Dh)
Bits Field Description
3:0 SIDETONE_ This programs the attenuation applied to the microphone preamp output to produce a sidetone signal.
ATTEN
SIDETONE_ATTEN Attenuation
0000
2
-Inf
0001
2
−30 dB
0010
2
−27 dB
0011
2
−24 dB
0100
2
−21 dB
0101
2
to 1010
2
−18 dB to −3 dB
1011
2
to 1111
2
0 dB
(1) An active SIDETONE path to an audio output may result in the microphone DC blocking caps causing audio pops under the following
situations:1) Switching between internal and external microphone operation while in chip modes '10' or '11'.2) Toggling in and out of
powerdown/standby modes.3) Toggling between chip modes '10' and '11' whenever external microphone operation is selected.4) The
insertion/removal of a headset while in chip modes '10' or '11' whenever external microphone operation is selected.To avoid potential
pop noises, it is recommended to set SIDETONE_ATTEN to '0000' until DC points have stabilized whenever the SIDETONE path is
used.
CP_INPUT CONFIGURATION REGISTER
This register is used to control the differential cell phone input.
Table 21. CP_INPUT (0x0Eh)
Bits Field Description
4:0 CPI_LEVEL This programs the gain/attenuation applied to the cell phone input.
CPI_LEVEL Level
00000
2
−34.5 dB
00001
2
−33 dB
00010
2
−31.5 dB
00011
2
−30 dB
00100 to 11100
2
−28.5 dB to +7.5 dB
11101
2
+9 dB
11110
2
+10.5 dB
11111
2
+12 dB
5 CPI_MUTE If set, the CPI input is muted at source.
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