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ams AG
The technical content of this austriamicrosystems document is still valid.
Contact information:
Headquarters:
ams AG
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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
A
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
© 2003-2009, austriamicrosystems AG, 8141 Unterpremstaetten, Austria-Europe. All Rights Reserved.
www.austriamicrosystems.com Revision 0.1
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ams AG
Technical content still valid
AS3502 rev 1_1 demo board
austriamicrosystems
Preliminary Product Brief, Confidential
© 2003-2009, austriamicrosystems AG, 8141 Unterpremstaetten, Austria-Europe. All Rights Reserved.
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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ams AG
Technical content still valid
AS3502 rev 1_1 demo board
austriamicrosystems
Preliminary Product Brief, Confidential
© 2003-2009, austriamicrosystems AG, 8141 Unterpremstaetten, Austria-Europe. All Rights Reserved.
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.
Revision 0.1
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ams AG
Technical content still valid
AS3502 rev 1_1 demo board
austriamicrosystems
Preliminary Product Brief, Confidential
© 2003-2009, austriamicrosystems AG, 8141 Unterpremstaetten, Austria-Europe. All Rights Reserved.
www.austriamicrosystems.com
Copyright
Copyright © 2009, austriamicrosystems AG, Schloss Premstaetten, 8141 Unterpremstaetten, Austria-Europe.
Trademarks Registered ®. All rights reserved. The material herein may not be reproduced, adapted, merged,
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
For Sales Offices, Distributors and Representatives, please visit:
www.austriamicrosystems.com
austriamicrosystems – a leap ahead
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