AK5373 Datasheet, PDF (18/53 Pages) Asahi Kasei Microsystems – 24-bit Stereo ADC with USB Interface

[AK5373]
■ External Digital Audio Interface
The AK5373 has optional audio streaming interface to output A/D data, or to receive DSP data and to transmit them to the
host. Because the AK5373 operates as a master device only, MCLK, LRCK, and BICK are output. The AK5373 supports
two audio formats, I2S and MSB justified format. The data length of ADC outputs is 24bit only despite the USB audio
formats which can be selected from 8/16/24 bit. This interface is specified in the header of EEP-ROM.
AK5373
DSP
MCLK
B IC K
LRCK
SDTO
SDTI
512fs or 256fs
64fs
1f s
MCLK
BCLK
LRCK
SDTI
SDTO
Figure 15. External Digital Audio Interface
512FS bit
MCLK pin
0
256fs
1
512fs
Table 7. MCLK Output Frequency
I2S bit
0
1
SDTO
SDTI
MSB justified
I²S Compatible
MSB justified
I²S Compatible
Table 8. Audio Interface Format
■ Volume & Mute Control
The AK5373 has a digital volume control which ranges from +24dB to -31dB in 1dB step. The maximum volume, the
minimum and default volumes are defined by EEP-ROM header setting.
When ZCE bit = “1” (Zero cross detection enable), L-channel and R-channel volumes are changed independently on zero
cross or zero cross timeout. Zero cross timeout is set by ZTM1-0 bits (Table 9). When ZCE bit = “0” (zero cross detection
disable), the volume is changed immediately. Mute operation and zero cross detection have the same relation as the
volume mentioned in this section.
ZTM1
bit
0
0
1
1
ZTM0
bit
0
1
0
1
Zero Crossing Timeout Period
8kHz
16kHz
44.1kHz
128/fs
16ms
8ms
2.9ms
256/fs
32ms
16ms
5.8ms
512/fs
64ms
32ms
11.6ms
1024/fs
128ms
64ms
23.2ms
Table 9. Zero Crossing Timeout Period
The AK3573 has the LMUTEN and RMUTEN pins, and it can control mute operation from the device side. However,
because the AK5373 does not have HID function, the mute operation by these pins cannot be acknowledged by the host.
There are two modes for the mute operation by LMUTEN and RMUTEN pins; one is normal mute and the other is
one-shot mute.
MS1202-E-00
- 18 -
2010/06