Datasheet

Maxim Integrated │ 108
MAX98090 Ultra-Low Power Stereo Audio Codec
www.maximintegrated.com
Table 38. Quick Configuration Mode Lookup
fixed and cannot be manually changed. In this mode,
when the sample rate is set to 8kHz or 16kHz, voice filters
(IIR) are automatically selected and the ADC oversam-
pling rate is fixed to 128. For any other selected sample
rate, music filters (FIR) are selected and the ADC overs-
ampling rate is configured to insure that the pre-scaled
master clock frequency is greater than or equal to 256 x
fS. If f
PCLK
≥ 256 x f
S
then the oversampling rate (OSR) is
set to 128, otherwise OSR is set to 64. Table 38 provides
a complete lookup table for the resulting quick configura-
tion mode settings.
Exact Integer Mode
In exact integer mode, the master clock frequency and sam-
ple rate can be set to one of eight preprogrammed combi-
nations (Table 39). There are four different available mas-
ter clock frequencies (12MHz/13MHz/16MHz/19.2MHz),
each of which can be selected with a sampling rate (f
S
)
of either 8kHz or 16kHz. Once a configuration is selected,
the NI and MI bits are internally programmed to the cor-
rect ratio. These combinations are primarily intended for
standard or wideband voice applications.
Table 39. Clock Mode Configuration Register
SELECTED MASTER CLOCK
FREQUENCY
SELECTED SAMPLE RATE (kHz)
8 16 32 44.1 48 96
f
MCLK
DIVIDER f
PCLK
VOICE FILTER (IIR) MUSIC FILTER (FIR)
26MHz 2 13Mhz OSR = 128 OSR = 128 OSR = 128 OSR = 128 OSR = 128 OSR = 64
19.2MHz 1 19.2Mhz OSR = 128 OSR = 128 OSR = 128 OSR = 128 OSR = 128 OSR = 64
13MHz 1 13Mhz OSR = 128 OSR = 128 OSR = 128 OSR = 128 OSR = 128 OSR = 64
12.288MHz 1 12.288Mhz OSR = 128 OSR = 128 OSR = 128 OSR = 128 OSR = 128 OSR = 64
12MHz 1 12MHz OSR = 128 OSR = 128 OSR = 128 OSR = 128 OSR = 128 OSR = 64
11.2896MHz 1 11.2896MHz OSR = 128 OSR = 128 OSR = 128 OSR = 128 OSR = 64 OSR = 64
256 x f
S
1 256 x f
S
OSR = 128 OSR = 128 OSR = 128 OSR = 128 OSR = 64 —
2 128 x f
S
— — — — — OSR = 64
ADDRESS: 0x1C
DESCRIPTION
BIT NAME TYPE POR
7
FREQ[3:0] R/W
0
Exact Integer Sampling Frequency (LRCLK) Conguration
Congure the DAI for specic PCLK to LRCLK ratios for f
S
= 8kHz/16kHz operation
(voice modes). Any setting other than 0x0 overrides manual ratio mode settings.
0000: Disabled 1XXX: Enabled Other combinations are reserved
When enabled, the following PCLK to LRCLK ratios are available:
1000: f
PCLK
= 12MHz, f
LRCLK
= 8kHz 1001: f
PCLK
= 12MHz, f
LRCLK
= 16kHz
1010: f
PCLK
= 13MHz, f
LRCLK
= 8kHz 1011: f
PCLK
= 13MHz, f
LRCLK
= 16kHz
1100: f
PCLK
= 16MHz, f
LRCLK
= 8kHz 1101: f
PCLK
= 16MHz, f
LRCLK
= 16kHz
1110: f
PCLK
= 19.2MHz, f
LRCLK
= 8kHz 1111: f
PCLK
= 19.2MHz, f
LRCLK
= 16kHz
6 0
5 0
4 0
3 — — — —
2 — — — —
1 — — — —
0 USE_MI R/W 0
Use MI[15:0] in Addition to NI[14:0] to set an Accurate Frequency Ratio
0 : MI = 65536; NI = (f
LRCLK
/ f
PCLK
) x 65536 x 96
1 : MI is set to the value of MI[15:0] (Table 42 and Table 43).