AK5373 Datasheet, PDF (14/53 Pages) Asahi Kasei Microsystems – 24-bit Stereo ADC with USB Interface

[AK5373]
OPERATION OVERVIEW
■ Overview of AK5373
The AK5373 is a stereo A/D converter with USB interface. It is easy to use since the control logic including USB audio
class, stereo differential microphone amplifiers, two PLL’s USB serial interface engine, and FIFO are integrated. All
Descriptor contents are stored in EEP-ROM and customizable. For example, when supporting a mono microphone by
48kHz sampling rate only, what needed to be done is to prepare appropriate USB descriptor. There is no need for writing
program codes.
The AK5373 also has an external audio steaming interface to connect other A/D converters or audio DSP’s. When a high
performance A/D converters is connected, A/D data generated by this A/D converter are transmitted via USB upstream.
When an external audio DSP is connected, the output of AK5373 is processed by this DSP. The AK5373 receives this data
again and transmits. I/F format is stored in the EEP-ROM header.
The AK5373 integrates the following blocks:
1. 24bit High Performance Stereo A/D Converter
a) S/N: 91dB (MIC Gain=0dB), S/N: 78dB (MIC Gain=+30dB)
2. MIC Power Supply
a) Output Voltage: 2.2V (typ)
3. Differential Microphone Amplifier
a) Setting of Gain: 0dB, +6dB, +12dB, +18dB, +24dB, +30dB, +36dB
4. Digital Programmable Gain
a) Gain Range: from +24dB to -31dB (Setting of gain: Max, Min and Initial value)
b) Gain Step: 1dB/step (Fix)
5. PLL
a) 16.0MHz or 24.0MHz crystal generator with output buffer (Available for External Clock input)
b) Two PLLs
- A/D_PLL: generate audio clock
- System_PLL: generate USB system clock
6. Audio Synchronization Type
a) Synchronous Type
- Isochronous transfer uses Synchronous type synchronization which is synchronous to SOF (start of
frame) packets which are issued per 1ms.
7. USB Audio Format
a) Supports 7 Frequencies: 8kHz, 11.025kHz, 16kHz, 22.05kHz, 32kHz, 44.1kHz, 48kHz
b) Stereo/Mono 24bit/16bit/8bit LSB first
8. FIFO
a) Synchronization between A/D converter and USB bus
- Memory Size 576 bytes: 24bit (3 bytes) x 48 samples x 2 channel x 2 frames
9. USB Serial Interface Engine
a) Process USB Standard Requests
10. Control block of Audio Device Class
a) Translate internal A/D format to USB audio class format
b) Process USB Audio Class Request
- Mute
- Gain/Attenuation
- Sampling Frequency Control
11. USB transceiver
12. EEP-ROM I/F
SPI™ (4-wire) type EEP-ROM can be used to customize all USB descriptors and any functions.
- 8K bits (AK6506C) or larger
13. USB Suspend/Resume Support
14. External Digital Audio Interface
a) 24bit I²S or MSB justified
b) MCLK=256fs or 512fs, BICK=64fs
15. Stand-alone Mute
a) Zero Crossing detection mute or One Shot mute (not support HID function)
MS1202-E-00
- 14 -
2010/06