AK5373 Datasheet, PDF (20/53 Pages) Asahi Kasei Microsystems – 24-bit Stereo ADC with USB Interface

[AK5373]
■ Power Management Control
USB specifies that the current at suspend mode must not exceed 500μA. When the USB host is in suspend mode, the
SUSN pin also becomes to “L” in order to notify this mode to the external components like DSP’s to observe USB
specification.
■ Synchronization
The AK5373 supports synchronous type synchronization which is synchronous to SOF (start of frame) packets which are
issued per 1ms.
■ Descriptor’s Customization
USB audio class has very flexible, but complicated format. In order to keep both of the flexibility and simplicity to use,
the AK5373 utilizes the precompiled control information in EEP-ROM instead of direct USB audio class decoding. Data
in EEP-ROM is divided into two blocks; header information block and USB descriptor block. Header block size is fixed
while USB descriptor block size is variable. Header information includes various control information such as audio
format, the microphone’s gain, power management information, and etc. When the device is powered up, at first the
AK5373 reads the header block in EEP-ROM, and maps these values into the internal registers. Note that 8k bits or larger
SPI type EEP-ROM is available.
The AK5373 does not store all of the descriptors into internal memory at the boot time. Instead, the AK5373 reads the
descriptor from EEP-ROM and transmit it when it receives the “Get Descriptor” Request command. The AK5373
transmits NAK until it is ready to send data.
Header Information includes
1) Power Management Information
2) Microphone Gain
3) External Digital Audio Interface Information
4) Mute Control Information
5) Descriptor related information
a) PCM format(stereo/mono, resolution) and the related alternate setting number
b) Endpoint number
c) Initial/Minimum/Maximum Volume
MS1202-E-00
- 20 -
2010/06