AK4955 Datasheet, PDF (29/117 Pages) Asahi Kasei Microsystems – 24bit Stereo CODEC with MIC/SPK/Cap-less VIDEO-AMP/ LDO & DSP

[AK4955]
■ PLL Slave Mode (PMPLL bit = “1”, M/S bit = “0”)
A reference clock of PLL is selected among the input clocks to the MCKI or BICK pins. The required clock for the
AK4955 is generated by an internal PLL circuit. Input frequency is selected by PLL3-0 bits (Table 4).
a) PLL reference clock: MCKI pin
The BICK and LRCK inputs must be synchronized with MCKO output. The phase between MCKO and LRCK is not
important. The MCKO pin outputs the frequency selected by PS1-0 bits (Table 9) and the output is enabled by MCKO bit.
Sampling frequency can be selected by FS3-0 bits (Table 5)
AK4955
MCKI
MCKO
BICK
LRCK
SDTO
SDTI
11.2896MHz, 12MHz, 13.5MHz,
24MHz, 27MHz
DSP or μP
256fs/128fs/64fs/32fs
≥ 32fs
1fs
MCLK
BCLK
LRCK
SDTI
SDTO
Figure 19. PLL Slave Mode 1 (PLL Reference Clock: MCKI pin)
b) PLL reference clock: BICK pin
The sampling frequency corresponds to a range from 7.35kHz to 48kHz by changing FS3-0 bits (Table 6).
AK4955
MCKO
MCKI
BICK
LRCK
SDTO
SDTI
DSP or μP
32fs or 64fs
1fs
BCLK
LRCK
SDTI
SDTO
Figure 20. PLL Slave Mode 2 (PLL Reference Clock: BICK pin)
MS1343-E-00
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2011/12