ISD3900
Publication Release Date: Dec 10, 2013
- 45 -
Revision 1.5
AUD_IOUT_RMPUP
–
Enables the ramp up function on the current driver. After powering up
the current driver, a slow ramp is generated as an input to the current driver to prevent sudden
transients on the output. This bit enables the ramp up function to ramp current from zero to
center level.
AUD_IOUT_RMPDN
– Before powering down the current driver, this bit should be set to
prevent fast transients. Setting this bit ramps the current driver zero current.
MIC_EN
– Setting this bit to 1 in conjunction with powering down the ANAIN input amplifier
(
PU_ANAIN=0),
allows the use of pins ANAIN and ANAOUT as differential MIC inputs. In this
mode, the ANAIN and ANAOUT pins become MIC+ and MIC- and allow a differential input to
be applied to the ADC. The maximum level for this input is 1Vpp measured differentially. This
configuration is designed to be used in conjunction with the AGC to amplify microphone
signals while achieving good common mode rejection of supply noise. No mixing with AUXIN
is possible in this mode.
Table 12-21 ADC Input Source Selection
ADC_SEL
ADC_SEL[1:0]
Source
00
ANAIN
01
AUXIN
10
SUM1
11
N/A
Table 12-22 SUM2 Input Source Selection
OUT_SUM_SEL
OUT_SUM_SEL[1:0]
Source
00
ANAIN
01
SUM1
10
AUXIN
11
N/A
Table 12-23 CFG8 Register
CFG8 Configuration Register
Bit 7 - 4
Bit 3
Bit 2
Bit 1
Bit 0
-
MUTE_ADC_IN
MUTE_SUM2_MUX
MUTE_AUXOUT
MUTE_AUDOUT
Default 0x00:
NOT mute on analog signal path.