AS3430-EK-ST Datasheet, PDF (1/51 Pages) ams AG – Low Power Ambient Noise-Cancelling Speaker Driver

AS3400 AS3410 AS3430
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 background 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 configurations for best
trade-off of noise cancellation, required filtering 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 handset 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 function
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; <1µA quiescent
Extended PSRR for 217Hz
Interfaces
2-wire serial control mode & volume inputs
Calibration via Line-In or 2-wire serial interface (patent pending)
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
The devices are ideal for Ear pieces, Headsets, Hands-Free Kits,
Mobile Phones, and Voice Communicating Devices.
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