WM8912 datasheet(28/129 Pages) CIRRUS

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WM8912

Production Data

PD, Rev 4.1, February 2013

RETUNETM MOBILE PARAMETRIC EQUALIZER (EQ)

The ReTune

TM Mobile Parametric Equaliser is a circuit that can be enabled in the DAC path. The

function of the EQ is to adjust the frequency characteristic of the output to compensate for unwanted

frequency characteristics in the loudspeaker (or other output transducer). It can also be used to tailor

the response according to user preferences, for example to accentuate or attenuate specific

frequency bands to emulate different sound profiles or environments such as concert hall, rock etc.

The EQ is enabled using the EQ_ENA bit as shown in Table 9.

ADDRESS

BIT

LABEL

DEFAULT

DESCRIPTION

R134 (86h)

EQ1

EQ_ENA

EQ enable

0 = EQ disabled

1 = EQ enabled

Table 9 ReTune

TM Mobile Parametric EQ Enable

The EQ can be configured to operate in two modes - “Default” mode or “ReTune

TM Mobile” mode.

DEFAULT MODE (5-BAND PARAMETRIC EQ)

In default mode, the cut-off / centre frequencies are fixed as per Table 10. The filter bandwidths are

also fixed in default mode. The gain of the individual bands (-12dB to +12dB) can be controlled as

described in Table 11.

Note that the cut-off / centre frequencies noted in Table 10 are applicable to a DAC Sample Rate of

48kHz. When using other sample rates, these frequencies will be scaled in proportion to the selected

sample rate.

EQ BAND

CUT-OFF/CENTRE

FREQUENCY

100 Hz

300 Hz

875 Hz

2400 Hz

6900 Hz

Table 10 EQ Band Cut-off / Centre Frequencies

ADDRESS

BIT

LABEL

DEFAULT

DESCRIPTION

R135 (87h)

EQ2

4:0

EQ_B1_GAIN [4:0]

01100b

(0dB)

EQ Band 1 Gain

(see Table 12 for gain range)

R136 (88h)

EQ3

4:0

EQ_B2_GAIN [4:0]

01100b

(0dB)

EQ Band 2 Gain

(see Table 12 for gain range)

R137 (89h)

EQ4

4:0

EQ_B3_GAIN [4:0]

01100b

(0dB)

EQ Band 3 Gain

(see Table 12 for gain range)

R138 (8Ah)

EQ5

4:0

EQ_B4_GAIN [4:0]

01100b

(0dB)

EQ Band 4 Gain

(see Table 12 for gain range)

R139 (8Bh)

EQ6

4:0

EQ_B5_GAIN [4:0]

01100b

(0dB)

EQ Band 5 Gain

(see Table 12 for gain range)

Table 11 EQ Band Gain Control

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