AK4695 Datasheet, PDF(36/107 Page) Asahi Kasei Microsystems – 24bit 4ch CODEC with MIC/HP/SPK/LINE-AMP

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AK4695 Datasheet, PDF (36/107 Pages) Asahi Kasei Microsystems – 24bit 4ch CODEC with MIC/HP/SPK/LINE-AMP

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[AK4695]

(2) Low Pass Filter (LPF1)

This is composed with 1st order LPF. LFP1A13-0 bits and LFP1B13-0 bits set the coefficient of LPF. This coefficient

setting is common for all channels. LPF13-10 bit controls ON/OFF of the each channel. When the LPF1 is OFF, the audio

data passes this block by 0dB gain. The coefficient must be set when LPF13-10 bits = â0â, PMPFIL3-0 bits = â0â or

PMDSP bit = â0â. The LPF1 starts operation 4/fs(max) after when LPF1x bit =PMPFIL bit= PMDSP bit = â1â is set. Each

channel can be powered down individually by PMPFIL3-0 bits. The powered-down channel by PMPFFIL3-0 bits outputs

â0â.

fs: Sampling frequency

fc: Cut-off frequency

LPF1: LPF1A[13:0] bits =A, LPF1B[13:0] bits =B

(MSB= LPF1A13, LPF1B13; LSB= LPF1A0, LPF1B0)

1 + 1 / tan (ï°fc/fs)

1 ï 1 / tan (ï°fc/fs)

1 + 1 / tan (ï°fc/fs)

Transfer function

1 + z ï1

H(z) = A

1 + Bz ï1

The cut-off frequency must be set as below.

fc/fs ï³ 0.05 (fc min = 2400Hz at 48kHz)

(3) 2-band Equalizer

This block can be used as Equalizer or Notch Filter. A 2-band Equalizer (EQ1 and EQ2) is switched ON/OFF

independently by EQ13-10 and EQ23-20 bits. When the Equalizer is OFF, the audio data passes this block by 0dB gain.

The calculating delay time does not differ on each channel whether the equalizer is ON or OFF.

E1A15-0, E1B15-0 and E1C15-0 bits set the coefficient of EQ1. E2A15-0, E2B15-0 and E2C15-0 bits set the coefficient

of EQ2. The coefficient setting is common for all channels. The EQx (x=1ï¾2) coefficient must be set when EQx bit = â0â

or PMPFIL3-0 bits = â0â. EQ1-2 start operation 4/fs(max) after when EQx (x=1~5) = PMPFIL = PMDSP bit = â1âis set.

Each channel can be powered down individually by PMPFIL3-0 bits. The powered-down channel by PMPFIL3-0 bits

outputs â0â.

fs: Sampling frequency

fo1 ~ fo2: Center frequency

fb1 ~ fb2: Band width where the gain is 3dB different from center frequency

K1 ~ K2 : Gain ( -1 ï£ Kn < 3 )

EQ1: E1A[15:0] bits =A1, E1B[15:0] bits =B1, E1C[15:0] bits =C1

EQ2: E2A[15:0] bits =A2, E2B[15:0] bits =B2, E2C[15:0] bits =C2

(MSB=E1A15, E1B15, E1C15, E2A15, E2B15, E2C15 ; LSB= E1A0, E1B0, E1C0, E2A0, E2B0, E2C0)

MS1463-E-01

- 36 -

2014/12

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