AS3400 Datasheet, PDF (1/3 Pages) ams AG – Low Power Ambient Noise-Cancelling Speaker Driver

AS3400 AS3410 AS3430
Product Brief
Low Power Ambient Noise-Cancelling Speaker Driver
1 General Description
The AS3400/10/30 are speaker driver with Ambient
Noise Cancelling function for handsets, headphones or
ear pieces. It is intended to improve quality of e.g. music
listening, a phone conversation etc. by reducing back-
ground ambient noise.
The fully analog implementation allows the lowest power
consumption, lowest system BOM cost and most natural
received voice enhancement otherwise difficult to
achieve with DSP implementations. The device is
designed to be easily applied to existing architectures.
An internal OTP-ROM can be optionally used to store
the microphones gain calibration settings.
The AS3400/10/30 can be used in different configura-
tions for best trade-off of noise cancellation, required fil-
tering functions and mechanical designs.
The simpler feed-forward topology is used to effectively
reduce low frequency background noise. The feed-back
topology with either 1 or 2 filtering stages can be used to
reduce noise for a larger frequency range, and to even
implement transfer functions like speaker equalization,
Baxandall equalization, high/low shelving filter and to set
a predefined loop bandwidth.
The filter loop is optimized by the user for specific hand-
set electrical and mechanical designs by dimensioning
simple R, C components.
Most handset implementations will make use of a single
noise detecting microphone. Two microphones could be
used to allow for increased flexibility of their location in
the handset mechanical design. Using the bridged mode
allows to even drive high impedance headsets.
2 Key Features
Microphone Input
128 gain steps @0.375dB and MUTE with AGC
differential, low noise microphone amplifier
single ended or differential mode
improved supply for electret microphone
MIC gain OTP programmable
High Efficiency Headphone Amplifier
2x34mW, 0.1% THD @ 16Ω, 1.5V supply,
100dB SNR
bridged mode for e.g. 300Ω loads
click and pop less start-up and mode switching
Line Input
volume control via serial interface or volume pin
64 steps @ 0.75dB and MUTE, pop-free gain setting
single ended stereo or mono differential mode
ANC processing
feed-forward cancellation
feed-back cancellation with filter loop transfer func-
tion definable via simple RC components
simple in production SW calibration
12-30dB noise reduction (headset dependent)
10-2000Hz wide frequency active noise attenuation
(headset dependent)
Monitor Function
for assisted hearing, i.e. to monitor announcements
fixed (OTP prog.) ambient sound amplification to
compensate headphone passive attenuation
volume controlled ambient sound amplification
mixed with fixed (OTP prog.) attenuation of LineIn
Incremental Functions
ANC with or without music on the receiving path
improved dynamic range playback
OTP ROM for automatic trimming during production
(4 times programbable)
Performance Parameter
5/3.8mA @ 1.5V stereo/mono ANC; <1uA quiescent
extended PSRR for 217Hz
Interfaces
2 wire serial control mode & volume inputs
calibration via Line-In or 2-wire serial interface
single cell or fixed 1.0-1.8V supply with internal CP
Package
AS3400, AS3410 QFN24 [4x4mm] 0.5mm pitch
AS3430 QFN32 [5.x5mm] 0.5mm pitch
3 Applications
Ear pieces, Headsets, Hands-Free Kits, Mobile Phones,
Voice Communicating Devices
www.austriamicrosystems.com
Revision 0.2
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