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AK5371VQ

2ch A/D Converter with USB I/F

Asahi Kasei Microdevices 

ASAHI KASEI

[AK5371]

Overview of AK5371

The AK5371 is the advanced stereo A/D converter, which converts analog signal into USB audio class formats. As the AK5371

incorporates all functions to build USB Audio Input Device, the AK5371 doesn’t require additional micro-controller, memory, and a

transceiver. Moreover, as the AK5371 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 AK5371, one crystal, one regulator, and microphone unit(s). As the

AK5371 also has EEPROM interface, descriptors can be customized easily. The AK5371 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 AK5371 supports 5 sampling frequencies (8kHz, 11.025kHz, 22.05kHz, 44.1kHz, 48kHz). In order to support these

frequencies, the AK5371 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 AK5371 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 AK5371 notifies the

current state (normal state or suspend state) by SUS_N pin.

As the AK5371 has Microwire EEPROM I/F, the vendors can customize iManifacterer, iProduct, and the related strings to their

own ID, and string.

MS0103-E-00

MS0103-E-00

10

2001/06

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