IT6605
The IT6605 supports all audio formats and interfaces specified by the HDMI Specification v1.3 through
I2S, S/PDIF and optional one-bit audio outputs. The one-bit audio outputs take on the pins used by I2S
outputs, so only one between the two could be activated at a time.
I2S
Four I2S outputs are provided to support 8-channel uncompressed audio data at up to 192kHz sample
rate. A coherent multiple (master) clock MCLK is generated at pin 89 to facilitate proper functions of
mainstream backend audio DAC ICs. The supported multiplied factor and sample frequency as well as
the resultant MCLK frequencies are summarized in Table 2.
Audio sample frequency
Multiple of audio
sample frequency
32kHz
4.096
44.1kHz
5.645
48kHz
88.2kHz
11.290
22.579
33.869
45.158
56.448
67.738
79.027
90.316
96kHz
176.4kHz
22.579
192kHz
24.576
128
256
384
512
640
768
896
1024
6.144
12.288
18.432
24.576
30.720
36.864
43.008
49.152
12.288
24.576
36.864
49.152
61.440
73.728
86.016
98.304
8.192
11.290
16.934
22.579
28.224
33.868
39.514
45.158
45.158
49.152
12.288
16.384
20.480
24.576
28.672
32.768
67.738
73.728
90.317
98.304
(112.896)
(122.880)
(135.475) (147.456)
(158.054) (172.032)
(180.634) (196.608)
Table 2. Output MCLK frequencies (MHz) supported by the IT6605
Notes:
1. The MCLK frequencies in parenthesis are MCLK frequencies over 100MHz. These frequencies are implemented
in the IT6605 and could be output through register setting as well. However, the I/O circuit of the MCLK pin does
not guarantee to be operating at such a high frequency under normal operation conditions. In addition, few audio
backend ICs such as DACs support such high MCLK frequencies. Therefore, using the MCLKs in parenthesis is
strongly discouraged.
S/PDIF
The S/PDIF output provides 2-channel uncompressed PCM data (IEC 60958) or compressed
multi-channel data (IEC 61937) at up to 192kHz. By default the clock of S/PDIF is carried within the
datastream itself via coding. The IT6605 also supplies coherent MCLK in cases of S/PDIF output to
help ease the implementation with certain audio processing ICs.
One-Bit Audio (DSD/SACD)
Direct stream digital (DSD) audio is an one-bit audio format which is prescribed by Super Audio CD
Feb-2012 Rev:0.92 12/38
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