AK5371A Datasheet, PDF (10/32 Pages) Asahi Kasei Microsystems – 2ch A/D Converter with USB I/F

ASAHI KASEI
[AK5371A]
„ Overview of AK5371A
The AK5371A is the advanced stereo A/D converter, which converts analog signal into USB audio class formats. As the AK5371A
incorporates all functions to build USB Audio Input Device, the AK5371A doesn’t require additional micro-controller, memory, and
a transceiver. Moreover, as the AK5371A also has 20dB fixed gain pre-amplifier in addition to programmable gain amplifier
(IPGA) whose range is from +24dB to –31dB, this device is suitable for USB microphone, especially microphone array. USB
microphone can be manufactured easily by only four main components; the AK5371A, one crystal, one regulator, and microphone
unit(s). As the AK5371A also has EEPROM interface, descriptors can be customized easily. The AK5371A includes the following
blocks:
1. 2 channel 16bit A/D converter
a) 84dBA@fs=44.1kHz
2. Programmable Gain Amplifier (IPGA)
a) Gain Range: from +24dB to -31dB,
b) Gain Step: 1dB/step
3. Fixed Gain Preamplifier
a) 20dB
4. FIFO
Synchronization between A/D converter and USB bus
a) Memory Size 400 bytes (16bit wide x 100 depth x 2 channel)
5. PLL
a) 11.2896MHz crystal
b) Two PLLs
- A/D_PLL: generate clock for fs=8kHz, 48kHz
- System_PLL : generate USB system clock
6. Audio Format
a) supports 5 frequencies : 8kHz, 11.025kHz, 22.05kHz, 44.1kHz, 48kHz
b) 2 audio formats
- mono 16bit LSB first
- stereo 16bit LSB first
7. USB Serial Interface Engine
a) Process USB Standard Requests
8. 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
9. USB transceiver
10. EEPROM I/F
Microwire™ (4-wire) type EEPROM can be used to customize Device/String Descriptor.
- 1K bit (AK93C45A)
- 2K bit (AK93C55A)
- 4Kbit (AK93C65A)
11. USB Suspend/Resume Support
The AK5371A supports 5 sampling frequencies (8kHz, 11.025kHz, 22.05kHz, 44.1kHz, 48kHz). In order to support these
frequencies, the AK5371A incorporates PLL, which generates system clock and master clock for fs=8kHz, and 48kHz
Mute, volume and audio format including sampling frequency are controlled by USB audio class request.
The AK5371A goes to suspend mode when the device doesn’t receive SOF for the period more than 3ms. All blocks including
master clock stop the function to observe USB specification, 500μA , until receiving the resume signal. The AK5371A notifies the
current state (normal state or suspend state) by SUS_N pin.
As the AK5371A has Microwire™ EEPROM I/F, the vendors can customize iManifacterer, iProduct, and the related strings to
their own ID, and string.
MS0546-E-00
MS0103-E-00
10
2007/02