Datasheet
AUDIO SERIAL PORT OPERATION
AUDIO DATA INTERFACE FORMATS AND TIMING
LRCK
LeftChannel
0
12L
M
N
0
12LM
N
MSB
MSB
LSB
LSB
RightChannel
BCK
DIN
LRCK
N
M 2 1
0
L
LSB
MSB
N N
M 2 1
0
L
LSB
MSB
RightChannel
LeftChannel
BCK
DIN
PCM1789
SBAS451A – OCTOBER 2008 – REVISED JANUARY 2009 ..............................................................................................................................................
www.ti.com
The PCM1789 audio serial port consists of three signals: BCK, LRCK, and DIN. BCK is a bit clock input. LRCK is
a left/right word clock or frame synchronization clock input. DIN is the audio data input for VOUTL/R.
The PCM1789 supports six audio data interface formats: 16-/20-/24-/32-bit I
2
S, 16-/20-/24-/32-bit left-justified,
24-bit right-justified, 16-bit right-justified, 24-bit left-justified mode DSP, and 24-bit I
2
S mode DSP. In the case of
I
2
S, left-justified, and right-justified data formats, 64 BCKs, 48 BCKs, and 32 BCKs per LRCK period are
supported; however, 48 BCKs are limited to 192/384/768 f
S
SCKI, and 32 BCKs are limited to 16-bit right-justified
only. The audio data formats are selected by MC/SCL/FMT in hardware control mode and by the FMTDA[2:0]
bits in control register 17 (11h) in software control mode. All data must be in binary twos complement and MSB
first.
Table 4 summarizes the applicable formats and describes the relationships among them and the respective
restrictions with mode control. Figure 22 through Figure 26 show six audio interface data formats.
Table 4. Audio Data Interface Formats and Sampling Rate, Bit Clock, and System Clock Restrictions
MAX LRCK FREQUENCY
CONTROL MODE FORMAT DATA BITS (f
S
) SCKI RATE (xf
S
) BCK RATE (xf
S
)
16/20/24/32
(1)
192 kHz 128 to 1152
(2)
64, 48
I
2
S/Left-Justified
Software control Right-Justified 24, 16 192 kHz 128 to 1152
(2)
64, 48, 32 (16 bit)
(3)
24 192 kHz 128 to 768 64
I
2
S/Left-Justified DSP
Hardware control 16/20/24/32
(1)
192 kHz 128 to 1152
(2)
64, 48
I
2
S/Left-Justified
(1) 32-bit data length is acceptable only for BCK = 64 f
S
and when using I
2
S or Left-Justified format.
(2) 1152 f
S
is acceptable only for f
S
= 32 kHz, BCK = 64 f
S
, and when using I
2
S, Left-Justified, or 24-bit Right-Justified format.
(3) BCK = 32 f
S
is supported only for 16-bit data length.
Figure 22. Audio Data Format: 16-/20-/24-/32-Bit I
2
S
(N = 15/19/23/31, M = 14/18/22/30, and L = 13/17/21/29)
Figure 23. Audio Data Format: 16-/20-/24-/32-Bit Left-Justified
(N = 15/19/23/31, M = 14/18/22/30, and L = 13/17/21/29)
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Product Folder Link(s): PCM1789