LMV1031-20 Datasheet, PDF (1/10 Pages) National Semiconductor (TI) – Amplifier for Internal 3-Wire Analog Microphones and External Preamplifier

October 2005
LMV1031-20
Amplifier for Internal 3-Wire Analog Microphones and
External Preamplifier
General Description
The LMV1031 audio amplifier is an ideal replacement for the
JFET preamplifier that is currently used in the electret micro-
phones. The LMV1031 is optimized for applications that
require extended battery life, such as Bluetooth communica-
tion links. The supply current for the LMV1031 is only 72 µA.
This is a dramatic reduction from that required for a JFET
equipped microphone. The LMV1031, with its separate out-
put and supply pins, offers a higher PSRR and eliminates the
need for additional external components.
The LMV1031 is guaranteed to operate from 2V to 5V supply
voltage over the full temperature range, has a fixed voltage
gain of 20 dB and enhanced SNR performance. The
LMV1031 is optimized for an output biasing of 1.09V.
The LMV1031 has less than 200Ω of output impedance over
the full audio bandwidth. The gain response of the LMV1031
is flat within the audio band and is stable over the tempera-
ture range.
The LMV1031 is available in a large dome 4-bump ultra thin
micro SMD package that can easily fit on the PCB inside the
miniature microphone metal can (package). This package is
designed for microphone PCBs requiring 1 kg adhesion
criteria.
Features
(Typical LMV1031-20, 2V Supply; Unless Otherwise Noted)
n Signal to noise ratio
62 dB
n Output voltage noise (A-weighted)
−86 dBV
n Low supply current
72 µA
n Supply voltage
n Input impedance
2V to 5V
>100 MΩ
n Max input signal
n Output voltage
108 mV_PP
1.09V
n Temperature range
−40˚C to 85˚C
n Large Dome 4-Bump micro SMD package with improved
adhesion technology.
Applications
n Mobile communications - Bluetooth
n Accessory microphone products
n Cellular phones
n PDAs
Block Diagram
Electret Microphone
20150801
© 2005 National Semiconductor Corporation DS201508
20150804
www.national.com