austriamicrosystems AG is now
ams AG
The technical content of this austriamicrosystems document is still valid.
Contact information:
Headquarters: ams AG
Tobelbaderstrasse 30
8141 Unterpremstaetten, Austria
Tel: +43 (0) 3136 500 0 e-Mail: [email protected]
Please visit our website at www.ams.com
austriamicrosystems AS3502 rev 1_1 demo board
Preliminary Product Brief, Confidential
Application Note #02, Confidential
Active Noise Cancelling
AS3502 rev 1_1 demo board operation
1 Eval Board Description
Power Switch Monitor Mode Enable Button
ON OFF
Volume Poti
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VOL
Power LED
I2C
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I2C Connector
Jumper J6: VOL/CSDA pin Mode Select
AAA Battery Connector
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Line In valid
Earbud
Technical
© 2003-2009, austriamicrosystems AG, 8141 Unterpremstaetten, Austria-Europe. All Rights Reserved.
www.austriamicrosystems.com
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austriamicrosystems AS3502 rev 1_1 demo board
Preliminary Product Brief, Confidential
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 above.
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 ears 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
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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 valid performance operational amplifiers and the analog circuit design. ams can provide low frequency noise down to 100Hz or lower.
Note: Noise cancelling is very subjective. Best results 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 removed 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
Technical
Other items to highlight include :
© 2003-2009, austriamicrosystems AG, 8141 Unterpremstaetten, Austria-Europe. All Rights Reserved.
www.austriamicrosystems.com
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AS3502 rev 1_1 demo board
Preliminary Product Brief, Confidential
3.4.1 Power consumption: austriamicrosystems
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.
AG still valid
Technical
© 2003-2009, austriamicrosystems AG, 8141 Unterpremstaetten, Austria-Europe. All Rights Reserved.
www.austriamicrosystems.com
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AS3502 rev 1_1 demo board
Preliminary Product Brief, Confidential austriamicrosystems
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 is believed to be correct and accurate. However, valid 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.
Headquarters:
AG still austriamicrosystems AG
Business Unit Communications
A 8141 Schloss Premstätten, Austria
T. +43 (0) 3136 500 0
F. +43 (0) 3136 5692 [email protected] content www.austriamicrosystems.com
– a leap ahead
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