LMV1089 Datasheet, PDF (1/32 Pages) National Semiconductor (TI) – Dual Input, Far Field Noise Suppression Microphone Amplifier with Automatic Calibration Capability

LMV1089
May 19, 2010
Dual Input, Far Field Noise Suppression Microphone
Amplifier with Automatic Calibration Capability
General Description
The LMV1089 is a fully analog dual differential input, differ-
ential output, microphone array amplifier designed to reduce
background acoustic noise, while delivering superb speech
clarity in voice communication applications.
The LMV1089 preserves near-field voice signals within 4cm
of the microphones while rejecting far-field acoustic noise
greater than 50cm from the microphones. Up to 20dB of far-
field rejection is possible in a properly configured and cali-
brated system.
Part of the Powerwise™ family of energy efficient solutions,
the LMV1089 consumes only 1.1mA of supply current pro-
viding superior performance over DSP solutions consuming
greater than ten times the power.
A quick calibration during the manufacturing test process of
the product containing the LMV1089 compensates the entire
microphone system. This calibration compensates for mis-
match in microphone gain and frequency response, as well
as acoustical path variances. The LMV1089 stores the cali-
bration coefficients in the on-chip EEPROM. The calibration
is initiated by an I²C command or by a logic pin control.
The dual microphone inputs and the processed signal output
are differential to provide excellent noise immunity. The mi-
crophones are biased with an internal low-noise bias supply.
Key Specifications
■ Far Field Noise Suppression
(Electrical), (f = 1kHz)
■ Supply Voltage
■ Supply Current
■ Standby Current
■ Signal-to-Noise Ratio (A-weighted)
■ Total Harmonic Distortion + Noise
■ PSRR (217Hz)
37dB
2.7V to 5.5V
1.1mA (typ)
0.7µA (typ)
65dB (typ)
0.1% (typ)
96dB (typ)
Features
■ ^{Low power consumption}
■ ^{Shutdown function}
■ ^{No added processing delay}
■ ^{Differential inputs and outputs}
■ ^{Automatic calibration}
■ ^{Adjustable 6 - 48dB gain}
■ ^{Excellent RF immunity}
■ ^{Space-saving 36–bump micro SMD package}
Applications
■ ^{Headset and Boom microphones}
■ ^{Mobile handsets and two-way radios}
■ ^{Bluetooth and other powered headsets}
■ ^{Hand-held voice microphones}
■ ^{Equalized stereo microphone preamplifier}
© 2010 National Semiconductor Corporation 300472
FIGURE 1.
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