AK4545 Datasheet, PDF (24/33 Pages) Asahi Kasei Microsystems – AC97 AUDIO CODEC WITH SRC AND DIT

[ASAHI KASEI]
[AK4545]
n Extended Audio ID(Index 28h)
The Extended Audio ID(28h) is a read only register. 2bits D15&D14 can be read for codec identification. As AK4545
operates as only primary CODEC, D15 ,14 are automatically set to “0”.
The AMAP bit D9 of this read only register for the AK4545 will always be set to “1” indicating that the codec slot DAC
mapping conform to AC’97 Rev 2.1.
Since AK4545 supports variable sample rates, field of D0: VRA is set to 1, indicates Variable Rate PCM Audio is
supported.
n Extended Audio Status and Control Register (Index 2Ah)
Bits D0 to D3, and D11 to D14 are read/write controls, while D6 to D9 are read only data to controller.
Bit
Function
VRA=1
Enables Variable Rate Audio mode in conjunction with Audio Sample Rate
(D0)
Control Registers and tag-bit/SLOTREQ signaling
Because CDAC,LDAC,SDAC, and MICADC are not supported, default value at cold register reset for D11-D14 is set
to “0”.
Internal SRC related circuits are controlled by this VRA bit(2Ah), not by VRA in Extended Audio ID register(28h).
n Audio Sample Rate control Registers (Index 2Ch, 32h)
Sample Rate controls for DACs, and ADC. 16bit data in D15(MSB) to D0 show unsigned value between 0 to 65535,
representing the exact sampling frequency in Hz. These Sample Rate setting is done at VRA=1 of Extended Audio
Status and Control Register(2Ah).
Sample Rate (kHz)
Data in D15 – D0
8.0
1F40 hex
11.025
2B11 hex
16.0
3E80 hex
22.05
5622 hex
32.0
7D00 hex
44.1
AC44 hex
48.0
BB80 hex
The AK4545 supports these discrete frequencies. When any other codes is written in this register, the AK4545 works
at the sampling rate rounded to the closest one above by decoding of only D15-D12 bits.
D15 – D12
Sample Rate (kHz)
0,1
8.0
2
11.025
3
16.0
4,5
22.05
6,7,8
32.0
9,Ah
44.1
Bh-Fh
48.0
At VRA=0, 2Ch and 32h are “BB80h” and can’t be written. When VRA is set to 0, 2Ch and 32h register are set to
“BB80h” automatically.
And the sample rate changing will be executed on the fly(immediately). It is recommended to set the zero data(no
input/no ouput) at the fs changing in order to prevent some noise.
MS0058-E-00
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2000/11