Datasheet

Maxim Integrated │ 101
MAX98090 Ultra-Low Power Stereo Audio Codec
www.maximintegrated.com
Table 28. DSP Biquad Filter Enable Register
Table 29. Record Path Biquad Digital Preamplifier Level Configuration Register
Record Path Biquad Filter
The record path DSP has a single stage digital biquad fil-
ter with a programmable preattenuation amplifier. The dig-
ital biquad filter configuration applies to both the left and
right record channels. To enable the record path biquad
filter, set RECBQEN high (Table 28). Once enabled, the
level of preattenuation can be adjusted from 0dB down to
-15dB (denoted A
V_BQ
, see Table 29). The digital biquad
filter cannot be set to a gain greater than ±12dB, to a Q
greater than 10, or to below a minimum f
C
that varies by
filter type. See the Electrical Characteristics table.
The digital biquad coefficients are uninitialized at power-
up, and if the filter is going to be used, the coefficients
must be programmed before the device and biquad filter
are enabled. The transfer function is:
12
01 2
12
01 2
B BZ B Z
H(z)
A AZ A Z
−−
−−
+× + ×
=
+× + ×
ADDRESS: 0x41
DESCRIPTION
BIT NAME TYPE POR
7 — — — —
6 — — — —
5 — — — —
4 — — — —
3 RECBQEN R/W 0
Enable Biquad Filter in Record Path
0: Biquad lter not used.
1: Biquad lter used in record path.
2 EQ3BANDEN R/W 0
Enable 3-Band EQ in Playback Path (Bands 4–7 Are Not Used)
0: 3-band EQ disabled.
1: 3-band EQ enabled. Only valid if EQ7BANDEN = 0 and EQ5BANDEN = 0.
1 EQ5BANDEN R/W 0
Enable 5-Band EQ in Playback Path (Bands 6 and 7 Are Not Used)
0: 5-band EQ disabled.
1: 5-band EQ enabled. Only valid if EQ7BANDEN = 0
0 EQ7BANDEN R/W 0
Enable 7-Band EQ in Playback Path
0 : 7-band EQ disabled.
1 : 7-band EQ enabled. This makes EQ5BANDEN and EQ3BANDEN redundant.
ADDRESS: 0x19
DESCRIPTION
BIT NAME TYPE POR
7 — — — —
6 — — — —
5 — — — —
4 — — — —
3
AVBQ[3:0] R/W
0
ADC Biquad Digital Preamplier Gain Conguration
2 0
0x0: +0dB
0x1: -1dB
0x2: -2dB
0x3: -3dB
0x4: -4dB
0x5: -5dB
0x6: -6dB
0x7: -7dB
0x8: -8dB
0x9: -9dB
0xA: -10dB
0xB: -11dB
0xC: -12dB
0xD: -13dB
0xE: -14dB
0xF: -15dB
1 0
0 0