SSM2529ACBZ-R7 datasheet(16/52 Pages) AD

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SSM2529

Data Sheet

Rev. 0 | Page 16 of 52

The common biquad filter transfer function is

−

H(z)

The first-order IIR filter transfer function is

−

H(z)

In normal mode, the supported coefficients range from −4 to

approximately +4. For equalizer mode, this range means that

the cutoff and center frequencies can vary from 40 Hz to

12 kHz when the input sampling rate is 48 kHz, and the peak

gain varies from −18 dB to +18 dB.

The EQ_FORMAT bit in Register 0x54 defines the coefficient

format. The default value is 0, and the corresponding format is

Q3.13. Setting this bit to 1 achieves a larger coefficient range (from

−8 to approximately +8), which enables a larger gain boost or

decreases the range.

Online coefficient update is supported. If the filter bank

coefficients are updated when the EQ is operating, set the

EQ_UPD bit after the coefficient is written. The coefficient

update procedure requires approximately 0.05 ms to complete.

The read only bit, EQ_UPDING, in the EQ_CTRL1 register

represents the coefficient update status. If the system clock is

removed during this period, the update procedure cannot be

finished, and the EQ_UPD_CLR bit must be set to cancel this

update.

The filter bank can be disabled, and all seven bands can be

bypassed separately to save power. The corresponding bits are

EQEN and EQBP1 to EQBP7 in Register 0x55.

Table 12. EQ Coefficients Registers

Address

Description

0x16

EQ1_COEF0_HI[15:8]

EQ Band 1, Coefficient 0 MSB

0x17

EQ1_COEF0_LO[7:0]

EQ Band 1, Coefficient 0 LSB

0x18

EQ1_COEF1_HI[15:8]

EQ Band 1, Coefficient 1 MSB

0x19

EQ1_COEF1_LO[7:0]

EQ Band 1, Coefficient 1 LSB

0x1A

EQ1_COEF2_HI[15:8]

EQ Band 1, Coefficient 2 MSB

0x1B

EQ1_COEF2_LO[7:0]

EQ Band 1, Coefficient 2 LSB

...

0x52

EQ7_COEF2_HI[15:8]

EQ Band 7, Coefficient 2 MSB

0x53

EQ7_COEF2_LO[7:0]

EQ Band 7, Coefficient 2 LSB

Table 13. EQ_CTRL1 Register

EQ_RESERVED

EQ_

UPDING

EQ_UPD_

CLR

EQ_

FORMAT

EQ_

UPD

Table 14. Bit Description of EQ_CTRL1 Register

Bit Name

Description

Settings

EQ_RESERVED

Reserved

EQ_UPDING

EQ coefficient

updating flag

0: EQ coefficients

updating

1: None

EQ_UPD_CLR

EQ coefficient update

clear

0: normal operation

1: interrupt

coefficient update

EQ_FORMAT

EQ coefficient format

selection

0: normal

1: large gain

EQ_UPD

EQ coefficient registers

update flag

1: update

0: none

Table 15. EQ_CTRL2 Register

EQEN

EQBP7

EQBP6

EQBP5

EQBP4

EQBP3

EQBP2

EQBP1

Table 16. Bit Description of EQ_CTRL2 Register

Bit Name

Description

Settings

EQEN

EQ enabled

0: EQ disabled

1: EQ enabled

EQBP7

EQ Band 7 bypass

when EQ enabled

0: no bypass

1: bypass EQ Band 7

EQBP6

EQ Band 6 bypass

when EQ enabled

0: no bypass

1: bypass EQ Band 6

EQBP5

EQ Band 5 bypass

when EQ enabled

0: no bypass

1: bypass EQ Band 5

EQBP4

EQ Band 4 bypass

when EQ enabled

0: no bypass

1: bypass EQ Band 4

EQBP3

EQ Band 3 bypass

when EQ enabled

0: no bypass

1: bypass EQ Band 3

EQBP2

EQ Band 2 bypass

when EQ enabled

0: no bypass

1: bypass EQ Band 2

EQBP1

EQ Band 1 bypass

when EQ enabled

0: no bypass

1: bypass EQ Band 1

The typical characteristic of each EQ band is shown in Figure 29 to

Figure 36.

Figure 29. Low-Pass Shelving Filter Frequency Response Across Bandwidth

Settings

–15

–10

–5

100M

10M

100k

10k

FREQUENCY (Hz)

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