AK5370 - AKM Semiconductor, Inc.

AK5370 - AKM Semiconductor, Inc.

ASAHI KASEI

[AK5370]

AK5370

USB I/F A/D Converter

Features:

n

Incorporates USB Audio Controller

USB Serial Interface Engine

Audio Class Encoder/Decoder

2 Endpoints (FIFO)

USB transceiver

n

16 bit A/D Converter

1 channel

Mute/Volume Control

AGC pin for external control

A/D S/N: 84dBA (44.1kHz, Gain = 0dB)

n

On-chip PLL

5 Sampling Frequencies support

8kHz, 11.025kHz

22.05kHz, 44.1kHz, 48kHz

n

Programmable Gain Amplifier

+20dB to –58dB

n

Single Power Supply, Low Power

+3.3Volts

±

10%

n

Package

24pin VSOP

General Description

The AK5370 is AD converter for USB audio, especially

USB microphone . The AK5370 integrates USB serial interface engine, USB transceiver, audio class decoder, endpoints, and high quality AD converter into t he chip.

As the AK5370 incorporates PLL, it can support several sampling frequencies, 8kHz, 11.025kHz, 22.05kHz, 44.1kHz, and 48kHz with only one crystal. Moreover, the AK5370 integrates volume control, and mute function.

It is possible to make USB microphone with a few external components

This device is good for not only business application such as conferencing but also games, voice recognition, and

Karaoke.

Related Documents

For the detail of USB specification, and Audio Class, please refer to the following documents.

Universal Serial Bus Specification Revision 1.1

Universal Serial Bus Device Class Definition for Audio

Devices, Revision 1.0

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VA VCOM

AGND

AGC AGCEN

VD

DGND

String ROM Config ROM

MIC_BIAS

Common Voltage

Power

Management

Mute

&

Volume control

Audio Class

Decoder

Audio Class

Encoder

EndPoint0

OUT_FIFO

EndPoint0

IN_FIFO

Serial

Interface

Engine

MIC_IN

-

+

-

+

AMP1O AMP2I AMP2O

16bit

ADC

EndPoint1

IN_FIFO

adCLK

PLL

VREF

LFLT1

System

CLK

USB

Transceiver

XTLIN

LFLT2

CRYSTAL

XTLOUT

RST

Testmode1,2

TEST1,2,3

DP

DN

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No. Signal Name

1 DGND

2 VD

3 DP

4 DN

5 TESTMODE3

6 XTALOUT

7 XTALIN

8 TESTMODE2

9 LFLT2

10 LFLT1

11 VCOM

12 MICIN

13 AMP1O

14 AMP2I

15 VA

16 AGND

17 VREF

18 AMP2O

19 TESTMODE1

20 MICBIAS

21 TEST

22 AGCE

23 AGC

24 RSTN

[AK5370]

I/O D

I D

O A

I A

I A

O A

O A

O A

I A

O A

I A

P A

P A

O A

O A

I A

O A

I D

I D

I/O Ana / Dig

P D

P D

I/O D

O

I

D

D

Pin/Function

Description

Ground

Digital Power Supply, 3.3V

USB bus Non-Inverting pin.

Because AK5370 is full speed mode device, 1.5k

Ω resistor will be connected between D+ node to VD.

USB bus Inverting Pin.

Please tie down to AGND for normal operation.

Crystal Oscillator Output, Connect Crystal Resonator

Crystal Oscillator Input, Connect Crystal Resonator

Please tie down to AGND for normal operation.

System clock PLL loop filter Pin. Connect 18k

resistor and

6800pF capacitor in series externally. adPLL loop filter Pin. Connect 51k Ω resistor and 8200pF capacitor in series externally.

Analog Common Voltage Reference Pin

Microphone

1 st

2 nd

Input

Amplifier Output Pin

Amplifier Input Pin

Analog Power Supply, 3.3V

Ground

ADC Common Voltage Reference Pin.

2 nd Amplifier Output Pin

Please tie down to AGND for normal oper ation.

Voltage Reference Output for the Microphone’s bias voltage

When this chip goes into Suspend mode, this pin goes to Hi -Z.

Please tie down to AGND for normal operation.

AGC Enable Control Input Pin.

When the external AGC is used, High level should be applied to this pin. When Low input is applied, AGC configuration

ROM data is set FALSE. Then AGC output is set to Low.

AGC Control Pin

When the host requests set AGC_CONTROL request, this pin goes to “H”.

“L” level AGCE input prevents this AGC_CONTROL request.

Low level output at SUSPEND. Default output at Reset is

Low.

Reset Pin, Low input makes the chip reset sate.

Schmitt Trigger input.

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Absolute Maximum Rating

AGND, DGND=0V

Parameter Symbol

Power Supplies

Analog

Digital

|DGND-AGND|

Input Current (any pins except for supplies)

Analog Input Voltage

Digital Input Voltage

Ambient Temperature

Storage Temperature

VA

VD

GND

IIN

VINA

VIND

Ta

Tstg

-0.3

-0.3

-

-0.3

-0.3

0

-40

4.5

4.5

0.3

±

10

VA+0.3

VD+0.3

70

125 mA

V

V

°

C

°

C

V

V

V

Note 1. All voltages with respect to ground

Warning: Operation at or beyond these limits may results in permanent damage to the device. N ormal operation is not guaranteed at these extremes.

AGND, DGND=0V

Parameter

Recommended Operating Condition

Power Supplies

Analog

Digital

VA

VD

3.0

3.0

3.3

3.3

All voltages with respect to ground.

* AKM assumes no responsibility for the usage beyond the condition in this datasheet.

3.6

3.6

V

V

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Analog Characteristics

Ta=25

°

C, VA=VD=3.3V, Signal Frequency=1kHz, Sampling Frequency Fs=44.1kHz

Mono ADC (1 channel)

Resolution

S/N (A weight)

(1 st and 2 nd MIC amplifier are set to 0dB)

S/(N+D) (-0.5dB analog input)

(1 st

and 2 nd

MIC amplifier are set to 0dB)

76 84 dBA

62 70 dB

MIC Amplifier (2 nd Stage) <IPGA> Characteristics

Input Voltage

Gain Control Range

Step Size

Input Impedance @AMP2I pin

MIC amplifier(1 st

Stage)

-58

0

1.6

1.0

20

20

2.0

Vp-p dB dB

K

Gain range(defined by external resistors)

External Feedback Impedance

MIC Bias

Output Voltage when 4.7K

resistor connected

Output Impedance

Output Current

Power Supplies

Analog

Digital

Total

Power Down(Suspend Mode)

0

20

0.9VA

200

+20

500

10.5

8.5

4.7

3

30 dB

K

Vdc

Ω mA mA mA mA mA

FILTER CHARACTERISTICS

(Ta=25

°

C VA, VD =3.0 - 3.6 V ; fs = 44.1 kHz)

Parameter Symbol

A/D Digital Filter

(Decimation LPF)

Passband PB

Stopband

Passband Ripple

Stopband Attenuation

Group Delay

A/Ddigital Filter (HPF)

Frequency Response

+/- 0.2 dB

-3 dB

-0.5 dB

-0.1 dB

PR

SA

GD

0

SB

FR

17.64

26.5

68

+/- 0.2 dB

0.5

6.85

19.2

44.9

KHz

KHz dB ms

Hz

Hz

Hz

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Digital DC Characteristics

Ta=0 - 70

°

C; VD=3.0 - 3.6V; DGND=0V Measurement under static state

All digital pins except DP, DN. Schmitt hysteresis level of RST pin and levels of all test pins will not be tested.

Parameter Symbol

AGCE pin “H” level input voltage

AGCE pin “L” level input voltage

RSTN pin “H” level voltage

RSTN pin “L” level voltage

“L” level output voltage IOL= -2mA

Input Leakage Current

VIH

VIL

VIHR

VILR

“H” level output voltage IOH= 2mA VOH

VOL

Iin

70%VA

2.0

2.4

±

30%VA

0.8

0.6

10

V

V

V

V

V

V

µ

A

Switching Characteristics

Ta=25

°

C, VA=VD=3.3V

Parameter Symbol

Master Clock Frequency

Reset input width @RSTN pin(low active)

Singe Ended Receiver Threshold

Main Clock Stable Time

Vse(max) of D+ to stabilized MCLK

( X’tal oscillator start up + PLL lock -in )

Reset Signal Recognition

Both D+ and D- < Vse(min) to Reset mode

Device Ready

Ready for transaction after reset

Suspend Recognition

Idle state ( D+ > Vse(max) & D- < Vse(min) )

to Suspend mode

Resume Time

First flip of D+/D- from Idle sate

To Device Ready*)

MCLK

Wrst

-

1.0

11.2896 - MHz us

Vse 0.8 2.0 V

Trst_rec

Tsus_rec 3.0

2.5 5.5 µ s

ms

Device Ready: VREF, X’tal oscillator, and PLL get stable and bus trans action with normal rate is ready.

VD

D+

D- "L"

RST

Master

Clock

Tostb

Reset Mode

Device

Connected

Tdrr

T rst_rec

Reset Mode

Figure 1. Mode change with respect to BUS States 1 (Power on and device connected)

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Tsus_rec

VD”H”

D+

D-

RST”H”

Master

Clock

Tresm

Figure 2. Mode Change with respect to Bus States 2 (Bus transactions)

Ta=25 ° C; VD=3.3V; DGND=0V; CL=50pF

Transmitter Characteristics

Parameter Symbol

Data Rate DR DP,DN

Output Impedance (Hi)

Output Impedance (Lo)

“H” level Output Voltage

“L” level Output Voltage

Tri-state Leakage Current

Rise/Fall Time

Rise/Fall Time Matching

Crossover Point

11.97

Roh DP, DN DP, DN=”H”

Rol

Vohd

Vold

Iolk

Trf/Tff

Trfm

Vcrs

DP, DP

DP, DN

DP, DN=”L”

IOH=-200uA 2.8

DP, DN IOH=2.2mA

DP, DN 0 < DP, DN< 3.3V -10

DP, DN

DP, DN

DP, DN

4

T rf

T rs

T ff

T fs

DP, DN

90%VDD

10%VDD

12

30

30

12

100

1.6

12.03

0.3

10

20

MHz

V

V

µ

A ns

%

V

Figure 3. Rise/Fall Time

DP, DN

Figure 4. Crossover Point

Vcrs

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Receiver Characteristics

Ta=25

°

C; VD=3.3V; DGND=0V

Parameter Symbol

Schmitt High Level Voltage

Schmitt Low Level Voltage

Vihs

Vils

DP, DN

DP, DN

2.0

DP, DN

Vihs

Vils

0.8

V

V

[AK5370]

Figure 5. Schmitt Level Voltage

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[AK5370] n Overview of AK5370

The AK5370 is the advanced A/D converter, which converts analog signal of condenser microphone into USB audio class formats. This device is suitable for USB microphone. The AK5370 includes the following blocks:

1. AD converter

2. Pre-Amplifier with variable gain/attenuation

3. Serial Interface Engine

4. Control block of Audio Device Class

Support Mute, Gain/Attenuation, Sampling Frequency Control, and AGC (only decode the request)

5. USB transceiver

AK4170 compliant

6. FIFO memory for bus synchronization

Memory Size (16bit wide x 100 depth)

7. PLL

Synchronize Audio Stream data with USB bus I/F

The AK5370 supports 5 sampling frequencies (8kHz, 11.025kHz, 22.05kHz, 44.1kHz, 48kHz) mute control, volume control of Feature

Unit in Audio Device Class. In addition to this, as the AK5370 decodes the AGC request, and puts “H” or “L” level to the external pin,

AGC pin, it is easy to implement AGC with external circuit.

In order to support these frequencies, the AK5370 incorporates PLL. In addition to this, as the AK5370 consumes low power, it is possible to operate as bus-powered device. n Class & Descriptor Overview

USB peripheral usually belongs to a group, “Class”. The AK5370 belongs to Audio Device Class. The Class consists of four

Descriptors, Device Descriptor, Configuration Descriptor, Interface Descriptor, and Endpoint Descriptor. The AK5370 has Audio

Specific Interface Descriptor and Endpoint Descriptor.

(1) Device Descriptor

Device Descriptor describes the product information; product name, manufacturer, etc. In addition to this, Device Descriptor has

Endpoint0 fifo-buffer size. At enumeration phase, host reads 8 bytes from the top of Device Descriptor at first. The host knows by reading bMaxPacketSize0 in the Device Descriptor, and uses this value for the following transactions, and does not send the bigger data at once.

(2) Configuration Descriptor

Configuration Descriptor informs the host of the number of Interface, Bus-powered/Self-Powered device, etc.

This descriptor is the same as Standard Interface Descriptor.

(3) Interface Descriptor

There are two Interfaces in Audio Class; Audio Control (AC) Interface, and Audio Streaming (AS) Interface.

Each Audio Interface includes Standard Interface Descriptor and Class-Specific Interface.

Standard AC Interface Descriptor describes interface’s class.

Class-Specific AC Interface Descriptor is a concatenation of all the descriptors that are used to fully describe the audio function.

As the AK5370 has three logical audio functions; Input Terminal, Output Terminal, and Feature Unit (mute, volume, AGC), each terminal and unit has their own Descriptor.

Not only each descriptor has their own information, but also has connection information between the blocks.

For example, bSourceID field in Output Terminal Descriptor is 0x03, which is ID of Feature Unit. This means that Feature Unit is connected to Output Terminal.

Standard AS Interface has the interface class name (AUDIO) and sub-class name (AUDIO_STREAMING), the related Endpoint number, etc.

Class-Specific AS Interface Descriptor mainly shows Audio Data Format information that follows as Descriptor.

There is a note for Alternate Setting:

Alternate setting 0 is a zero-bandwidth setting, used to relinquish the claimed bandwidth on the bus when the microphone is not in use. It is the default setting after power-up. The zero bandwidth is implemented by specifying that this alternate setting of the interface has no endpoints associated with it (bNumEndpoints=0).

(4) Endpoint Descriptor

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Endpoint Descriptor is a pipe for the data. The AK5370 has two Endpoints. One is Endpoint0 for Control Transfer. Another is

Endpoint 1, whose direction is IN, is used for Isochronous Transfer. Standard AS Isochronous Endpoint tells Endpoint type like

In/OUT, maximum packet size, synchronization type, etc. to the host.

Main information of Class-Specific AS Endpoint Descriptor is sampling frequency.

Figure 6 shows Descriptor’s hierarchy.

Device

Device

Descriptor

Configuration

Configuration

Descriptor

Interface

Standard Audio Control

Interface Descriptor

Class-Specific Audio Control

Interface Descriptor

Class-Specific Descriptor

StandardInterface Descriptor

Standard AS Interface

Descriptor Alt. Setting 0

Standard AS Interface

Descriptor Alt. Setting 1

Class-Specific Audio Streaming

Interface Descriptor

Class-Specific AS Format Type

Descriptor

Standard AS Isochronous

Endpoint Descriptor

Class-Specific AS Isochronous

Endpoint Descriptor

Endpoint

(IN)

Figure 6. Descriptor Hierarchy

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[AK5370] n Synchronization

The AK5370 operates as Asynchronous Device. A/D converter in the AK5370 operates asynchronously with USB SOF timing. The data from A/D converter are sent continuously to a buffer memory while the data are burstly transferred at the interval of SOF on the

USB. In order to control the difference of timing, AK5370 has a FIFO memory with a capacity of 2-frame depth .The average sampling rate calculating from USB frame should be in accordance with A/D sampling rate (fs).

The following figure shows an example. When sampling frequency is set to 44.1kHz, the number of data is almost 44 samples in one frame. But the AK5370 must send 45 samples in once per ten times. Please see Figure 7.

N Frame (N+1) Frame (N+9) Frame (N+10) Frame

44 samples 44 samples 45 samples 44 samples

Figure 7. Synchronization

The data sampled by A/D converter in N Frame are output to the USB bus on somewhere the (N+1) frame by issuing IN transfer. n Power Management Control

In the normal operation, MICBIAS outputs the voltage to supply the microphone’s bias voltage.

When idle state continues for 3ms, the AK5370 goes to suspend state and forces ADC block and other unnecessary block to power-down mode. MICBIAS pin does not supply the bias voltage to save power consumption and is open state under suspend state.

The device resumes the normal operation within 30ms after the device receives resume signal n Feature Unit Control & Frequency Control

The AK5370 has three feature unit function; mute, volume, and AGC.

The host issues “SET_FEATURE_UNIT_CONTROL” request to change the volume, the status of mute or AGC. The AK5370 responds to the request for CUR value only, not respond for MIN, MAX, RES value. Note that the AK5370 doesn’t have AGC circuit itself and that it decodes AGC request only.

The host can get the CUR/MAX/MIN/RES value of the volume by requesting “GET_FEATURE_CONTROL”. However, only CUR value is supported for mute and AGC.

Volume Control Format of USB Audio Class is a) 16-bit integer, b) upper-bye is integer (-127 to 127), and lower-bye is fraction.

The AK5370 follows the conversion table described in Table 1 in page 22 for the volume control request

When the AK5370 receives “SET_ENDPOINT_CONTROL” request, it changes sampling frequency(fs). If fs is not supported, the device forces to set the appropriate fs which it supports. The host can get fs by issuing “GET_ENDPOINT_CONTROL” request.

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AK5370 Descriptors Specification

1. Product description

This device is one channel 16-bit ADC with USB I/F for monaural microphone, and operates as IN device.

2. Descriptor structure

This device includes one configuration, two interfaces, which are an audio control interface (0) and an audio streaming interface (1), two endpoints, which are endpoint 0 for default pipe, and endpoint

1 for audio streaming.

The descriptor is partly fixed and partly programmable by means of selectable test pin map. The programmable descriptors are marked with a star.

3. Device descriptor

Offset Field

0

2

4 bLength bcdUSB bDeviceClass

Size Value Description

1

2

1

0x12

1 bDescriptorType 1

0x0110

0x00

5 bDeviceSubClass 1

Size of this descriptor in bytes descriptor

1.10 – current revision of USB spec.

Device defined at Interface level

0x00 Unused

0x00 Unused

7 bMaxPacketSize0 1

2 8 idVendor

10

12 idProduct bcdDevice

14 iManufacturer

2

2

0x0001

0x0001

1

00 means Audio Product, 01 is AKMproduct ID ,

Device release code

0x01 “AKM”

15 iProduct 0x02 “AK5370”

16 iSerialNumber 1

17 bNumConfigurations

0x00 Unused

1

4. Configuration block

The configuration block consists of a confi guration descriptor followed by interface, endpoint, and class-specific descriptors.

4.1 Configuration descriptor

Offset Field

0

1 bDescriptorType 1

2 bLength wTotalLength

Size Value

1 0x09

2

0x02 CONFIGURATION

0x0076

Description

Size of this descriptor

Length of entire configuration block

Total 118 bytes including this interface descriptor.

4 bNumInterfaces

5 bConfigurationValue 1

6 iConfiguration

7 bmAttributes

8 MaxPower

1 0x02

1 0x00

1 0x80

1 0x2D

Two interfaces

Index of this configuration

Null

Bus Powered Device

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4.2 Audio control interface

The audio control interface describes the device structure and is used to manipulate the audio controls.

4.2.1 Interface descriptor

This descriptor describes a standard interface which includes USB class code and the index to class-specific information.

Offset Field

0 0x09

1 bDescriptorType 1

2

3 bLength bInterfaceNumber bAlternateSetting

Size Value

1

1

1

0x04 INTERFACE

0x00

0x00

4 bNumEndpoints 1 0x00

5 bInterfaceClass 1 0x01

6 bInterfaceSubclass 1 0x01

7 bInterfaceProtocol 1 0x00

8 iInterface 1 0x00

Description

Size of this descriptor

Index of this interface

Index of this setting

0

AUDIO

AUDIO_CONTROL

Unused

4.2.2 Class-specific interface header descriptor

Contains general information about the audio device.

Offset Field

0

0x24 CS_INTERFACE

2 bDescriptorSubtype 1 0x01

3

5

7

8 bLength bcdADC wTotalLength bInCollection baInterfaceNr(1)

Size Value

1

2

2

1

1

0x09

0x0100

0x0026

0x01

0x01

Description

Size of this descriptor subtype

Revision of class specification – 1.0

Total size of class-specific Audio Control

Interface descriptors (includes this descriptor)

Number of streaming interfaces

Streaming interface number 1 belongs to this audio control interface.

4.2.3 Input terminal descriptor

This descriptor describes the signal coming through the input port NumChannels is 1(monaural) and ChannelConfig is set no position. Terminal type is Microphone.

Offset Field

0

2 bDescriptorSubtype 1 0x02

3 bTerminalID 1 0x01

4 wTerminalType 2 0x0201

6 bAssocTerminal 1 0x02

7

8 bLength bNrChannels wChannelConfig

10 iChannelNames

11 iTerminal

Size Value

1

1

2

0x0C

0x24 CS_INTERFACE

0x01

0x0000

1 0x00

1 0x00

Description

Size of this descriptor

INPUT_TERMINAL

ID of this terminal

Terminal is Microphone

ID of associated Output Terminal is

0x02

One channel (Monaural)

Mono sets no position bits

Unused

Unused

4.2.4 Output terminal descriptor

This descriptor describes the USB stream to host.

Offset Field

0 bLength

Size Value

1 0x09

1 bDescriptorType 1

Description

Size of this descriptor

0x24 CS_INTERFACE

2 bDescriptorSubtype 1 0x03

3

4 wTerminalType 2 0x0101 USB

6

7 bTerminalID bAssocTerminal bSourceID

8 iTerminal

1

1

1

0x02

0x01

0x03

1 0x00

OUTPUT_TERMINAL

ID of this terminal

Streamer

ID of associate Input Terminal is 0x01

From Feature Unit

Unused

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4.2.5 Feature Unit descriptor

This descriptor describes Mute Control, Volume Control and Automatic Gain Control(AGC) .

Offset Field

0

1 bDescriptorType 1

2

3

4

5

6 bLength bDescriptorSubtype bUnitID bSourceID bControlSize bmaControls(0)

7 iFeature

Size Value

1

1

1

1

1

0x08

0x06

0x03

0x01

1 0x01

0x43*

1 0x00

Description

Size of this descriptor

FEATURE_UNIT descriptor subtype

ID of this feature Unit

ID to Terminal to which this is connected.

Size in bytes of an element of the bmaControl()

D0(Mute), and D1(Volume), D6(AGC) is enable

Unused

*) When “L” level is applied to AGCE pin, bmaControl (0) data is modified to 0x03 to state AGC is not enable.

Note that there is never endpoint descriptor for endpoint 0.

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4.3 Audio streaming interface

4.3.1 Zero bandwidth interface descriptor

Offset Field

0 0x09

1 bDescriptorType 1

2

3 bLength bInterfaceNumber bAlternateSetting

Size Value

1

1

1

0x04 INTERFACE

0x01

0x00

4 bNumEndpoints 1 0x00

5 bInterfaceClass 1 0x01

6 bInterfaceSubclass 1 0x02

7 bInterfaceProtocol 1 0x00

8 iInterface 1 0x00

Description

Length of this descriptor

Index of this interface

Index of this setting

0

AUDIO

AUDIO_STREAMING

Unused

4.3.2 Interface descriptor

Offset Field

0 0x09

1 bDescriptorType 1

2

3 bLength bInterfaceNumber bAlternateSetting

Size Value

1

1

1

0x04 INTERFACE

0x01

0x01

4 bNumEndpoints 1 0x01

5 bInterfaceClass 1 0x01

6 bInterfaceSubclass 1 0x02

7 bInterfaceProtocol 1 0x00

8 iInterface 1 0x00

Description

Length of this descriptor

Index of this interface

Index of this setting

1

AUDIO

AUDIO_STREAMING

Unused

4.3.3 Class-specific audio streaming interface descriptor

Offset Field

0 bLength

Size Value

1 0x07

1 bDescriptorType 1

Description

Length of this descriptor

0x24 CS_INTERFACE

2 bDescriptorSubtype 1 0x01

3 bTerminalLink

4 bDelay

5 wFormatTag

1 0x02

1 0x01

2 0x0001

AS_GENERAL

Unit ID of terminal(Output Terminal ID) delay

PCM

4.3.4 Type I format type descriptor

Offset Field

0 blength

Size Value

1 0x17

Description

Size of this descriptor

0x24 CS_INTERFACE

2 bdescriptorSubtype 1 0x02

3 bformatType 1

FORMAT_TYPE

0x01 FORMAT_TYPE_I

4 bNrChannels

5 bSubFrameSize

6 bBitResolution

8 tSamFreq[0]

11 tSamFreq[1]

14 tSamFreq[2]

17 tSamFreq[3]

20 tSamFreq[4]

1 0x01

1 0x02

1 0x10

3 0x001F40

Two bytes per slot

16

Five

8000Hz

3 0x002B11 11025Hz

3 0x005622

3 0x00AC44

3 0x00BB80

22050Hz

44100Hz

48000Hz

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4.4 Endpoint descriptor

4.4.1 Standard Endpoint Descriptor

Offset Field

0

2

3

6 bLength

4 wMaxPacketSize wInterval

Size Value

1 0x07

1 bDescriptorType 1 bendpointAddress bmAttributes

1

1

2 0x0064 2byte*50sample*1ch=100

1

0x05 ENDPOINT

0x81

0x01

0x01

Description

Length of this descriptor

Endpoint 1, IN direction

Isochronous, asynchronous, not shared byte/frame

One packet every frame (Must be set to 1)

4.4.2 Class-specific isochronous audio data endpoint descriptor

Offset Field

0 bLength

Size Value

1 0x07

1 bDescriptorType 1

Description

Size of this descriptor

0x25 CS_ENDPOINT

2 bDescriptorSubtype 1 0x01

3 bmAttributes 1 0x01

4 bLockDelayUnits 1 0x00

5 wLockDelay 2 0x0000

GENERAL

Sample rate control

Unused

4.5 String descriptor 1

String descriptors use UNICODE. except for LANGI D.

4.5.1 LANGID (0x00) Field

Offset Field

0 bLength 0x04

1 bDescriptorType 1

2 bString

Size Value

1

Description

Length of this descriptor

0x03 STRING descriptor

2 0x0409 “English(US)”

4.5.2.1 iManufacterer (0x01) Field in Device Descriptor

Offset Field

0 bLength

2 bString

Size Value

1 0x022

1 bdescriptorType 1

Description

Length of this descriptor

0x03 STRING descriptor

6 0x0041 “AKM ”

0x004B

0x004D

0x0020

0x0020

0x0020

0x0020

0x0020

0x0020

0x0020

0x0020

0x0020

0x0020

0x0020

0x0020

0x0020

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4.5.3.1iProduct (0x02) Field in Device Descriptor

Offset Field

0 bLength

2 bString

Size Value

1 0x22

1 bDescriptorType 1

Description

Length of this descriptor

0x03 STRING descriptor

12 “AK5370 ” 0x0041

0x004B

0x0035

0x0033

0x0037

0x0030

0x0020

0x0020

0x0020

0x0020

0x0020

0x0020

0x0020

0x0020

0x0020

0x0020

[AK5370]

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[AK5370]

5. Standard requests

5.1 Clear Feature

The AK5370 accepts “Clear Feature” request without stall. Though this request does not influence to the operation of the device, the AK5370 does not support this request.

5.2 Get Configuration

AKM USB Microphone should return the value, one, to the host.

Offset

0 bmRequestType 1 0x80

1 bRequest 1

2 wValue

4 wIndex

6 wLength

2

2

0x08 GET_CONFIGURATION

2

0x0000

0x0001 AKM USB Mic. has one configuration.

5.3 Get Descriptor

6

Offset Field Size Value Description

0 bmRequestType 1 0x80

1 bRequest 1

2 wValue

4 wIndex

ZZZZ is assigned by host:

High Byte is Descriptor Type, Low Byte is Index.

DEVICE : 0x0100 : (Index is 0 only)

CONFIGURATION : 0x0200

2

STRING: 0x03??(?? is 00, 01, 02)

0x0000 if wValue is DEVICE or CONFIGURATION, wIndex is zero. If wValue is 0x0300(LANGID), wIndex is zero. wLength 2 0xZZZZ

If wValue is 0x0301 or 0x0302, wIndex is 0x0409.

Descriptor Length (ZZZZ is assigned by host)

5.4 Get Interface

AKM USB Microphone has alternate Audio Streaming Interface, ;zero bandwidth, and normal.

So, the device returns the current selected bAlternateSetting v alue, 0x00(zero bandwidth Audio

Streaming Interface) or 0x01(normal Audio Streaming Interface). If wIndex is “0” (Audio Control

Interface), the device returns the value, “0x00.

Offset Field Size Value Description

0 bmRequestType 1 0x81

1 bRequest 1

2 wValue

4 wIndex

6 wLength

0x0000

0x0001

2 0x0001

Audio Control Interface

Audio Streaming Interface

AKM USB Mic. Has zero bandwidth Audio

Streaming Interface and normal Audio Streaming

Interface.

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5.5 Get Status

Offset Field Size Value

0 bmRequestType 1 0x80

0x81

0x82

Description

DEVICE

INTERFACE

ENDPOINT

1 bRequest 1

2 wValue

4 wIndex

6 wLength

2

2 0x0002

The AKM USB MIC returns the following status. a)

Device : 0x00 ( AKM USB MIC is bus-powered device) b)

Interface: 0x00 (All Zero) c)

Endpoint : 0x00

5.6 Set Address

AKM USB MIC stores the wValue in the internal memory as Device Address. In addition to this, the device returns ACK.

Offset Field Size Value

0 bmRequestType

Description

0x00 Zero

1 bRequest 1

2 wValue

4 wIndex 2

Device Address : ZZZZ is assigned by host

0x0000 Zero

6 wLength 2

5.7 Set Configuration

AKM USB MIC is placed to configured state only wValue of this request is 0x00 01. In addition to this, the device returns ACK.

Offset Field Size Value Description

0 bmRequestType 1 0x00 Zero

1 bRequest 1

2 wValue

4 wIndex

6 wLength

0x0000

0x0001 others

2

2

Unconfigured State

AKM USB MIC is set to configured state

Unconfigured State

0x0000 Zero

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5.8 Set Feature

The AK5370 accepts “Set Feature” request without stall. However note that the AK5370 does not support this request.

5.9 Set Interface

This request selects the alternate setting on interface 1 to control bandwidth allocation. Only

0x0000 is selected if wIndex is 0x0000 (Audio Control Interface) as current Interface.

Offset Field Size Value Description

0 bmRequestType 1 0x01 ONE

D7 0 = Host to device

D6..5 0 = Standard request

1 bRequest 1

D4..0 1 = Recipient is interface

0x0B SET_INTERFACE

2 wValue 2

0x0000

0x0001

Alternate Setting

Control Interface or Zero Bandwidth of

Streaming Interface

Normal Streaming

4 wIndex 0x0000

0x0001

Audio Control Interface

Audio Streaming Interface

6 wLength 2

5.10 Synch Frame

As AKM USB Microphone does not support this request , pipe is stalled.

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6. Device specific requests

AKM USB Microphone supports ONLY SET_CUR as bRequest field in Set Request Values.

6.1 Audio Control Request

AKM USB microphone support ONLY Feature Unit Control Request, not support other requests.

Addition to this, it only supports SET_CUR value as bRequest field in Set Feature Unit Control

Request Values. All Audio Control Requests are applied to channel 0, which means master channel.

6.1.1 Set Feature Unit Control Request

AKM USB Microphone supports only one form of parameter block. a) Mute Control

Offset Field Size Value Description

0 bmRequestType 1 0x21

1 bRequest 1

2 wValue

4 wIndex 2 0x0300

MUTE_CONTROL | CHANNEL_ 0

Upper Byte : bUnit ID field in Feature Unit

6 wLength 2 0x0001

The parameter block of mute control is the following.

Descriptor.(0x03)

Lower Byte : Audio Control Interface(0x00)

The Length of Mute Control Parameter Block

Offset Field

0 bMute

Size Value

1

0x00

Description

TRUE

FALSE b) Volume Control

Offset Field Size Value Description

0 bmRequestType 1 0x21

1 bRequest 1

2 wValue

4 wIndex 2 0x0300

VOLUME_CONTROL | CHANNEL_ 0

Upper Byte : bUnit ID field in Feature Unit

6 wLength 2

Descriptor.(0x03)

Lower Byte : Audio Control Interface(0x00)

Control

The parameter block of mute control is the following.

Offset Field

0 wVolume

Size Value

0xZZZZ

Description

The value is mapped to the volume register value.

(refer to Figure 3 conversion table )

ZZZZ is assigned by the host

If the wVolume exceeds the range, the AK5370 forces the value into the range. Please see the conversion table in the Get Feature Unit Control Request. c) Automatic Gain Control

Offset Field Size Value Description

0 bmRequestType 1 0x21

1 bRequest 1

2 wValue

4 wIndex 2 0x0300 Upper Byte : bUnit ID field in Feature Unit

Descriptor.(0x03)

Lower Byte : Audio Control Interface(0x00)

The Length of Mute Control Parameter Block 6 wLength

The parameter block of mute control is the following.

Offset Field

0 bAGC

2 0x0001

Size Value

1

0x00

Description

TRUE (AGC pin is “H”)

FALSE (AGC pin is “L”: Default)

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6.1.2 Get Feature Unit Control Request

AKM USB Microphone supports only one form of parameter block. a) Mute Control

Offset Field Size Value

0 bmRequestType 1 0xA1

Description

1 bRequest 1

2 wValue

4 wIndex 2 0x0300

6 wLength 2 0x0001

Upper Byte : bUnit ID field in Feature Unit

Descriptor.(0x03)

Lower Byte : Audio Control Interface(0x00)

The Length of Mute Control Parameter Block

The device outputs the current setting of mute status.

Offset Field

0 bMute

Size Value

1

0x00 b) Volume Control

Offset Field Size Value

0 bmRequestType 1 0xA1

1 bRequest 1

2 wValue

4 wIndex

0x82

0x83

0x84

2

2 0x0300

Description

TRUE

FALSE

Description

GET_CUR

GET_MIN

GET_MAX

GET_RES

VOLUME_CONTROL | CHANNEL_ 0

Upper Byte : bUnit ID field in Feature Unit

6 wLength 2

Descriptor.(0x03)

Lower Byte : Audio Control Interface(0x00)

The parameter block of Volume Control is the following.

Control

Offset Field

0 wVolume

Size Value

2

0xC600

0x1400

0x0100

Description bRequest = GET_CUR : returns current volume.

YY must be 00h bRequest = GET_MIN : -58dB bRequest = GET_MAX : +20dB bRequest = GET_RES : 1.0dB

Table 1 is the conversion map of USB class and internal volume register.

When host requests the volume value which is larger than the MAX value in the device, the device sets the MAX value to the volume. When host requests the volume value which is smaller than the MIN value in the device, the device sets the MIN value to the volume. RES value is 1.0dB.

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Field wVolume value Step

0x7FFF 20.0000

-------- ---------

0x1400 20.0000

0x13FF 19.0000

--------- --------

0x1301 19.0000

0x1300 19.0000

0x12FF 18.0000

--------- --------

0x1201 18.0000

0x1200 18.0000

--------- --------

--------- --------

0x02FF 2.0000

--------- --------

0x0201 2.0000

0x0200 2.0000

0x01FF 1.0000

--------- ---------

0x0101 1.0000

0x0100 1.0000

0x00FF 0.0000

--------- ---------

0x0001 0.0000

0x0000 0.0000

0xFFFF -1.0000

-------- --------

0xFF01 -1.0000

0xFF00 -1.0000

0xFEFF -2.0000

-------- --------

0xFE01 -2.0000

0xFE00 -2.0000

--------- ---------

--------- ---------

0xC700 -57.0000

0xC6FF -58.0000

--------- ---------

0xC601 -58.0000

0xC600 -58.0000

0xC5FF -58.0000

--------- ---------

0x8000 -58.0000

Table 1 Conversion Table of Volume Control

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[AK5370] c) Automatic Gain Control

Offset Field Size Value

0 bmRequestType 1 0xA1

Description

1 bRequest 1

2 wValue

4 wIndex 2 0x0300

6 wLength 2 0x0001

Upper Byte : bUnit ID field in Feature Unit

Descriptor.(0x03)

Lower Byte : Audio Control Interface(0x00)

The Length of Mute Control Parameter Block

The device outputs the current setting of AGC.

Offset Field

0 bAGC

Size Value

1

0x00

Description

TRUE (AGC pin is “H”)

FALSE (AGC pin is “L”)

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[AK5370]

6.2 Endpoint Control Request

The AK5370 supports five sampling frequencies. The sampling rate is changed when “Set

Endpoint Control Request ” is issued. SET_CUR, GET_CUR of bRequest is only supported.

GET_MIN, GET_ MAX, and GET_RES of bRequest are not supported.

6.2.1 Set Endpoint Control Request

Offset Field Size Value

0 bmRequestType 1

Description

0x22

1 bRequest

2 wValue

4

6 wIndex wLength

2

2

0x0100 Upper byte: SAMPLING_FREQ_CONTROL (0x01)

Lower byte : zero

0x0081

0x0003

Upper Byte : zero

Lower Byte : Endpoint Address (0x81)

The Length of Sampling Frequency Parameter

Block

The parameter block of mute control is the following.

Offset Field

0 iSampleFreq

Size Value Description

3 0xYYYYYY The following five values are valid. Others are invalid.

0x001F40 : 8kHz

0x002B11 : 11.025kHz

0x005622 : 22.05kHz

0x00AC44 : 44.1kHz(default)

0x00BB80 : 48kHz

If the iSampleFreq is different from the above values, the AK5370 forces sampling frequency to the appropriate value.

6.2.2 Get Endpoint Control Request

Offset Field Size Value

0 bmRequestType 1

Description

0xA2

1 bRequest

2 wValue

4

6 wIndex wLength

2

2

0x0100 Upper byte: SAMPLING_FREQ_CONTROL (0x01)

Lower byte : zero

0x0081

0x0003

Upper Byte : zero

Lower Byte : Endpoint Address (0x81)

The Length of Sampling Frequency Parameter

Block

The parameter block of mute control is the following.

Offset Field

0 iSampleFreq

Size Value Description

3 0xYYYYYY The following five values are valid. Others are invalid.

0x001F40 : 8kHz

0x002B11 : 11.025kHz

0x005622 : 22.05kHz

0x00AC44 : 44.1kHz

0x00BB80 : 48kHz

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24pin VSOP (Unit: mm)

*7.9

±

0.2

24 13

Package

A

1

0.22 +0.10

-0.05

0.12

M

12

0.65

Detail A

Seating Plane

0.08

NOTE: Dimension "*" does not include mold flash.

0-10

°

1.25

0.15+0.10

-0.05

0.10

±

0.05

±

0.20

[AK5370]

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Marking

AKM

AK5370VF

AAXXXX

1)

Pin #1 indication

2)

AA: LOT#

3)

Date Code: XXXXX(4 digits)

4)

Marketing Code: AK5370VF

5)

Asahi Kasei Logo

[AK5370]

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[AK5370]

IMPORTANT NOTICE

These products and their specifications are subject to change without notice. Before considering any use or application, consult the Asahi Kasei Microsystems Co., Ltd. (AKM) sales office or authorized distributor concerning their current status.

AKM assumes no liability for infringement of any patent, intellectual property, or other right in the application or use of any information contained herein.

Any export of these products, or devices or systems containing them, may require an export license or other official approval under the law and regulations of the country of export pertaining to customs and tariffs, currency exchange, or strategic materials.

AKM products are neither intended nor authorized for use as critical components in any safety, life support, or other hazard related device or system, and AKM assumes no responsibility relating to any such use, except with the express written consent of the Representative

Director of AKM. As used here:

(a) A hazard related device or system is one designed or intended for life support or maintenance of safety or for applications in medicine, aerospace, nuclear energy, or other fields, in which its failure to function or perform may reasonably be expected to result in loss of life or in significant injury or damage to person or property.

(b)A critical component is one whose failure to function or perform may reasonably be expected to result, whether directly or indirectly, in the loss of the safety or effectiveness of the device or system containing it, and which must therefore meet very high standards of performance and reliability.

It is the responsibility of the buyer or distributor of an AKM product who distributes, disposes of, or otherwise places the product with a third party to notify that party in advance of the above content and conditions, and the buyer or distributor agrees to assume any and all responsibility and liability for and hold AKM harmless from any and all claims arising from the use of said product in the absence of such notification.

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