AMS AS3502 User guide

Brand: AMS

Model: AS3502

Type: User guide

AMS AS3502 is a highly integrated low power Active Noise Cancellation (ANC) solution for mobile phone handsets and portable media players. It provides excellent noise cancellation performance in a very small form factor, making it ideal for space-constrained applications. The AS3502 features a 32-bit DSP engine that provides up to 24 dB of noise cancellation, and a low-power analog front-end that consumes only 3 mW in ANC mode. It also includes a high-performance headphone amplifier that delivers up to 12 mW of output power, and a low-noise microphone amplifier that provides excellent signal-to-noise ratio (SNR).

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Contact information:

Headquarters:

ams AG

Tobelbaderstrasse 30

8141 Unterpremstaetten, Austria

Tel: +43 (0) 3136 500 0

e-Mail: ams_sales@ams.com

Please visit our website at www.ams.com

AS3502 rev 1_1 demo board

austriamicrosystems

Preliminary Product Brief, Confidential

pplication Note #02, Confidential

Active Noise Cancelling

AS3502 rev 1_1 demo board operation

1 Eval Board Description

Power Switch

ON OFF

Volume Poti

Monitor Mode Enable Button

Jumper J6: VOL/CSDA

pin Mode Select

VOL I2C

AAA Battery Connector

I2C

Connector

Power LED

Line In

Earbud

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AS3502 rev 1_1 demo board

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Preliminary Product Brief, Confidential

www.austriamicrosystems.com

2 Operation

2.1 Set-Up :

Connect Sony Earbuds to Earbud connector

Insert battery, pay attention to polarity

Demo can be used with or without Line-In from Mp3 player or similar

Insert Earbuds in ear, pay attention to Left and Right ears

By default the demo is set up in stand-alone mode. Jumper 6 should be on the left according to the

image ab

ove.

2.2 Power On :

Toggle Power switch. Power LED will light to confirm power to the system.

After very short interval 0.5 – 1s the sound in your e

ars will change. You may experience slight

disorientation, this is normal and not dangerous.

If you have music or voice playing on the Line-In, you

can vary the Poti to change the volume.

2.3 Monitor :

By pressing the Monitor button, the Line In will be faded out and the ambient noise amplified.

The monitor mode is active for only as long as you maintain the button pressed.

Moving the volume poti in monitor mode will change the volume of the ambient noise.

3 Result

3.1 Hiss

With no Line-In you’re listening to noise generated by the electronics. Invariably this takes the form of

a hissing sound. With our demo, the hiss is significantly less than competition, due to the high

performance operational amplifiers and the analog circuit design.

3.2 Noise cancellation

The ideal environment to experiment the demo is a crowded room or with an air-conditioning fan, ie

real life environment. If you use a PC/speaker to generate sound you need to ensure the generator

can provide low frequency noise down to 100Hz or lower.

Note: Noise cancelling is very subjective. Best result

s are obtained by comparing existing solutions on

the market. Failing this, comparison curves are available in the product presentation.

3.3 Monitor

The traditional way to catch up on public announcements when listening to music is to rip the Earbuds

out of your ears. Then it takes a while to put them back in. The monitor mode is designed to avoid this

by attenuating the line in and amplifying the ambient noise.

Most ANC solutions on the market merely turn off the electronics in monitor mode, ie all music is

remove

d and you still have the passive damping caused by the Earbud. In addition you have a turn on

delay when you release the monitor function, that can be accompanied by pops and clicks. Our

solution treats this event electronically by maintaining some line in (volume programmable) and

amplifying the ambiant noise (volume programmable).

3.4 Others

Other items to highlight include :

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AS3502 rev 1_1 demo board

austriamicrosystems

Preliminary Product Brief, Confidential

www.austriamicrosystems.com

3.4.1 Power consumption:

The ANC function draws roughly 3mW. The true ground headphone amplifier draws roughly 5mW

(including charge pump etc). Complete feedforward ANC function with around 8mW.

3.4.2 Sound quality in Off:

Numerous manufacturers are concerned about the sound quality even with the ANC off. Our typical

application schematic shows an ON/OFF switch assembly that allows the user to bypass the chip in

off mode.

3.4.3 Footprint:

The feedforward bill of material requires less than 20 passive components in addition to the IC. The

total PCB area is typically less than 2cm2.

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Technical content still valid

AS3502 rev 1_1 demo board

austriamicrosystems

Preliminary Product Brief, Confidential

www.austriamicrosystems.com

translated, stored, or used without the prior written consent of the copyright owner.

All products and companies mentioned are trademarks of their respective companies.

4 Disclaimer

Devices sold by austriamicrosystems AG are covered by the warranty and patent identification provisions

appearing in its Term of Sale. austriamicrosystems AG makes no warranty, express, statutory, implied, or by

description regarding the information set forth herein or regarding the freedom of the described devices from

patent infringement. austriamicrosystems AG reserves the right to change specifications and prices at any time

and without notice. Therefore, prior to designing this product into a system, it is necessary to check with

austriamicrosystems AG for current information. This product is intended for use in normal commercial

applications. Applications requiring extended temperature range, unusual environmental requirements, or high

reliability applications, such as military, medical life-support or life-sustaining equipment are specifically not

recommended without additional processing by austriamicrosystems AG for each application.

The information furnished here by austriamicrosystems AG i

s believed to be correct and accurate. However,

austriamicrosystems AG shall not be liable to recipient or any third party for any damages, including but not

limited to personal injury, property damage, loss of profits, loss of use, interruption of business or indirect,

special, incidental or consequential damages, of any kind, in connection with or arising out of the furnishing,

performance or use of the technical data herein. No obligation or liability to recipient or any third party shall arise

or flow out of austriamicrosystems AG rendering of technical or other services.

5 Contact Information

Headquarters:

austriamicrosystems AG

Business Unit Communications

A 8141 Schloss Premstätten, Austria

T. +43 (0) 3136 500 0

F. +43 (0) 3136 5692

[email protected]

For Sales Offices, Distributors and Representatives, please visit:

www.austriamicrosystems.com

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AMS AS3502 User guide

AMS AS3502 User guide

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