Datasheet

Maxim Integrated │ 99
MAX98090 Ultra-Low Power Stereo Audio Codec
www.maximintegrated.com
Table 26. Right ADC Mixer Input Configuration Register
ADC Input Mixer Conguration
The device allows for each ADC input mixer to be con-
figured separately to accept any combination of valid
input sources. The ADC mixers can accept input from
the microphone PGAs (1 or 2), line input PGAs (A or B),
or directly differentially from any of the analog input pairs
(IN1/IN2, IN3/IN4, or IN5/IN6). The ADC input mixers then
route the selected sources to the left and right ADC inputs
(Tables 25 and Table 26).
Record Path FlexSound DSP
The digital record path is part of the FlexSound tech-
nology DSP and comprises multiple sequential DSP
blocks. The first DSP stage contains digital filters includ-
ing a voice filter (IIR), music filter (FIR), and a highpass
DC-blocking filter. The next stage is a digital biquad filter
with a pre-attenuation amplifier, and it is followed by a
digital gain and level control stage. The record path DSP
also features a digital sidetone path that is routed to and
mixed into the digital playback path (Figure 14).
Record Path Digital Filters
The record path DSP includes a digital filter stage. One
filter, set with the MODE bit (Table 27), offers the choice
between the IIR voice filters and the FIR music filters. The
IIR filters are optimized for standard (f
S
= 8kHz) and wide-
band (f
S
= 16kHz) voice applications, while the FIR filters
are optimized for low power operation at higher audio/
music sampling rates. For sampling rates in excess of
48kHz (f
LRCLK
> 48kHz), use the FIR music filters and set
the DHF bit. The MODE configuration selected applies to
both channels of both the record and playback path DSP.
The record path DSP also features a DC-blocking filter.
This filter can be used with both the IIR voice and FIR
music filters, and blocks low frequency (including DC)
input signals outside of the lower end of the audio band.
Table 25. Left ADC Mixer Input Configuration Register
ADDRESS: 0x16
DESCRIPTION
BIT NAME TYPE POR
7 — — — —
6
MIXADR[6:0]
R/W 0 Selects microphone input 2 to right ADC mixer.
5 R/W 0 Selects microphone input 1 to right ADC mixer.
4 R/W 0 Selects line input B to right ADC mixer.
3 R/W 0 Selects line input A to right ADC mixer.
2 R/W 0 Selects IN5/IN6 differential input direct to right ADC mixer (WLP only).
1 R/W 0 Selects IN3/IN4 differential input direct to right ADC mixer.
0 R/W 0 Selects IN1/IN2 differential input direct to right ADC mixer.
ADDRESS: 0x15
DESCRIPTION
BIT NAME TYPE POR
7 — — — —
6
MIXADL[6:0]
R/W 0 Selects microphone input 2 to left ADC mixer.
5 R/W 0 Selects microphone input 1 to left ADC mixer.
4 R/W 0 Selects line input B to left ADC mixer.
3 R/W 0 Selects line input A to left ADC mixer.
2 R/W 0 Selects IN5/IN6 differential input direct to left ADC mixer (WLP only).
1 R/W 0 Selects IN3/IN4 differential input direct to left ADC mixer.
0 R/W 0 Selects IN1/IN2 differential input direct to left ADC mixer.