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 A.
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 200
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 A
n
Supply voltage
2V to 5V
n
Input impedance
>
100 M
n
Max input signal
108 mV
PP
n
Output voltage
1.09V
n
Temperature range
-40C to 85C
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
20150801
Electret Microphone
20150804
October 2005
LMV1031-20
Amplifiers
for
Internal
3-W
ire
Analog
Microphones
and
External
Preamplifier
2005 National Semiconductor Corporation
DS201508
www.national.com
Absolute Maximum Ratings
(Note 1)
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.
ESD Tolerance (Note 2)
Human Body Model
2500V
Machine Model
250V
Supply Voltage
V
DD
- GND
5.5V
Storage Temperature Range
-65C to 150C
Junction Temperature (Note 6)
150C max
Mounting Temperature
Infrared or Convection (20 sec.)
235C
Operating Ratings
(Note 1)
Supply Voltage
2V to 5V
Temperature Range
-40C to +85C
2V and 5V Electrical Characteristics
(Note 3)
Unless otherwise specified, all limits are guaranteed for T
J
= 25C and V
DD
= 2V and 5V. Boldface limits apply at the tempera-
ture extremes.
Symbol
Parameter
Conditions
Min
(Note 4)
Typ
(Note 5)
Max
(Note 4)
Units
I
DD
Supply Current
V
IN
= GND
72
90
100
A
SNR
Signal to Noise Ratio
f = 1 kHz, V
IN
= 18 mV
PP
62
dB
THD
Total Harmonic Distortion
f = 1 kHz, V
IN
= 18 mV
PP
0.18
%
e
n
Output Noise
A-Weighted
-86
dBV
A
V
Gain
f = 1 kHz, V
IN
= 18 mV
PP
19.18
19.00
20.1
20.90
21.00
dB
f
LOW
Lower -3 dB Roll Off Frequency
R
SOURCE
= 50
, V
IN
= 18 mV
PP
72
Hz
f
HIGH
Upper -3 dB Roll Off Frequency
R
SOURCE
= 50
, V
IN
= 18 mV
PP
52
kHz
V
IN
Max Input Signal
f = 1 kHz and THD+N
<
1%
108
mV
PP
Z
IN
Input Impedance
>
100
M
C
IN
Input Capacitance
2
pF
V
OUT
Output Voltage
V
IN
= GND
890
875
1090
1310
1325
mV
R
O
Output Impedance
f = 1 kHz
<
200
PSRR
Power Supply Rejection Ratio
2V
<
V
DD
<
5V
56
dB
Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device is
intended to be functional, but specific performance is not guaranteed. For guaranteed specifications and the test conditions, see the Electrical Characteristics.
Note 2: The human body model (HBM) is 1.5 k
in series with 100 pF. The machine model is 0 in series with 200 pF.
Note 3: Electrical table values apply only for factory testing conditions at the temperature indicated. Factory testing conditions result in very limited self-heating of
the device such that T
J
= T
A
. No guarantee of parametric performance is indicated in the electrical tables under conditions of internal self-heating where T
J
>
T
A
.
Note 4: All limits are guaranteed by design or statistical analysis.
Note 5: Typical values represent the most likely parametric norm at the time of characterization.
Note 6: The maximum power dissipation is a function of T
J(MAX)
,
JA
and T
A
. The maximum allowable power dissipation at any ambient temperature is P
D
=
(T
J(MAX)
- T
A
)/
JA
. All numbers apply for packages soldered directly onto a PC board.
LMV1031-20
www.national.com
2
Connection Diagram
4-Bump Ultra Thin micro SMD
20150803
Top View
Note: - Pin numbers are referenced to package marking text orientation.
- The actual physical placement of the package marking will vary slightly from part to part. The package will designate the date code and will vary considerably.
Package marking does not correlate to device type in any way.
Ordering Information
Package
Part Number
Package Marking
Transport Media
NSC Drawing
4-Bump Ultra Thin
micro SMD lead free
LMV1031UR-20
Date Code
250 Units Tape and Reel
URA04JJA
LMV1031URX-20
3k Units Tape and Reel
LMV1031-20
www.national.com
3
Typical Performance Characteristics
Unless otherwise specified, V
S
= 2V, single supply, T
A
= 25C
Supply Current vs. Supply Voltage
Output Voltage vs. Supply Voltage
20150815
20150823
Gain vs. Supply Voltage
Closed Loop Gain and Phase vs. Frequency
20150824
20150816
Power Supply Rejection Ratio vs. Frequency
Total Harmonic Distortion vs. Frequency
20150817
20150818
LMV1031-20
www.national.com
4
Typical Performance Characteristics
Unless otherwise specified, V
S
= 2V, single supply, T
A
=
25C (Continued)
Total Harmonic Distortion vs. Input Voltage
Output Voltage Noise vs. Frequency
20150819
20150820
LMV1031-20
www.national.com
5
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