LMV1015
LMV1015 Analog Series: Built-in Gain IC's for High Sensitivity 2-Wire
Microphones
Literature Number: SNAS291A
LMV1015 Analog Series:
Built-in Gain IC’s for High Sensitivity 2-Wire
Microphones
General Description
The LMV1015 is an audio amplifier series for small form
factor electret microphones. This 2-wire portfolio is designed
to replace the JFET amplifier. The LMV1015 series is ideally
suited for applications requiring high signal integrity in the
presence of ambient or RF noise, such as in cellular com-
munications. The LMV1015 audio amplifiers are guaranteed
to operate over a 2.2V to 5.0V supply voltage range with
fixed gains of 15.6 dB and 23.8 dB. The devices offer excel-
lent THD, gain accuracy and temperature stability as com-
pared to a JFET microphone.
The LMV1015 series enables a two-pin electret microphone
solution, which provides direct pin-to-pin compatibility with
the existing older JFET market.
National Semiconductors built-in gain families are offered in
extremely thin space saving 4-bump micro SMD packages
(0.3 mm maximum). The LMV1015XR is designed for 1.0
mm ECM canisters and thicker. These extremely miniature
packages have the Large Dome Bump (LDB) technology.
This micro SMD technology is designed for microphone
PCBs requiring 1 kg adhesion criteria.
Features
(Typical LMV1015-15, 2.2V supply, R
L
= 2.2 kΩ, C = 2.2 µF,
V
IN
=18mV
PP
, unless otherwise specified)
nSupply voltage 2V - 5V
nSupply current <180 µA
nSignal to noise ratio (A-weighted) 60 dB
nOutput voltage noise (A-weighted) −89 dBV
nTotal harmonic distortion 0.09%
nVoltage gain
— LMV1015-15 15.6 dB
— LMV1015-25 23.8 dB
nTemperature range −40˚C to 85˚C
nLarge Dome 4-Bump micro SMD package with improved
adhesion technology.
Applications
nCellular phones
nHeadsets
nMobile communications
nAutomotive accessories
nPDAs
nAccessory microphone products
Schematic Diagram
20128901
Built-In Gain Electret Microphone
20128902
May 2005
LMV1015 Analog Series Built-in Gain IC’s for High Sensitivity 2-Wire Microphones
© 2005 National Semiconductor Corporation DS201289 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 −65˚C to 150˚C
Junction Temperature (Note 6) 150˚C max
Mounting Temperature
Infrared or Convection (20 sec.) 235˚C
Operating Ratings (Note 1)
Supply Voltage 2V to 5V
Operating Temperature Range −40˚C to 85˚C
Thermal Resistance (θ
JA
) 368˚C/W
2.2V Electrical Characteristics (Note 3)
Unless otherwise specified, all limits guaranteed for T
J
= 25˚C, V
DD
= 2.2V, V
IN
=18mV
PP
,R
L
= 2.2 kΩand C = 2.2 µF.
Boldface limits apply at the temperature extremes.
Symbol Parameter Conditions
Min
(Note 4)
Typ
(Note 5)
Max
(Note 4) Units
I
DD
Supply Current V
IN
= GND LMV1015-15 180 300
325 µA
LMV1015-25 141 250
300
SNR Signal to Noise Ratio f = 1 kHz,
V
IN
=18mV
PP
,
A-Weighted
LMV1015-15 60
dB
LMV1015-25 61
V
IN
Max Input Signal f = 1 kHz and
THD+N <1%
LMV1015-15 100 mV
PP
LMV1015-25 28
V
OUT
Output Voltage V
IN
= GND LMV1015-15 1.54
1.48
1.81 1.94
2.00 V
LMV1015-25 1.65
1.49
1.90 2.02
2.18
f
LOW
Lower −3dB Roll Off Frequency R
SOURCE
=50Ω65 Hz
f
HIGH
Upper −3dB Roll Off Frequency R
SOURCE
=50Ω95 kHz
e
n
Output Noise A-Weighted LMV1015-15 −89 dBV
LMV1015-25 −82
THD Total Harmonic Distortion f = 1 kHz,
V
IN
=18mV
PP
LMV1015-15 0.09 %
LMV1015-25 0.15
C
IN
Input Capacitance 2pF
Z
IN
Input Impedance >1000 GΩ
A
V
Gain f = 1 kHz,
R
SOURCE
=50Ω
LMV1015-15 14.0
13.1
15.6 16.9
17.5 dB
LMV1015-25 22.5
21.4
23.8 25.0
25.7
5V Electrical Characteristics (Note 3)
Unless otherwise specified, all limits guaranteed for T
J
= 25˚C, V
DD
= 5V, V
IN
=18mV
PP
,R
L
= 2.2 kΩand C = 2.2 µF.
Boldface limits apply at the temperature extremes.
Symbol Parameter Conditions
Min
(Note 4)
Typ
(Note 5)
Max
(Note 4) Units
I
DD
Supply Current V
IN
= GND LMV1015-15 200 300
325 µA
LMV1015-25 160 250
300
LMV1015 Analog Series
www.national.com 2
5V Electrical Characteristics (Note 3) (Continued)
Unless otherwise specified, all limits guaranteed for T
J
= 25˚C, V
DD
= 5V, V
IN
=18mV
PP
,R
L
= 2.2 kΩand C = 2.2 µF.
Boldface limits apply at the temperature extremes.
Symbol Parameter Conditions
Min
(Note 4)
Typ
(Note 5)
Max
(Note 4) Units
SNR Signal to Noise Ratio f = 1 kHz,
V
IN
=18mV
PP
,
A-Weighted
LMV1015-15 60
dB
LMV1015-25 61
V
IN
Max Input Signal f = 1 kHz and
THD+N <1%
LMV1015-15 100 mV
PP
LMV1015-25 28
V
OUT
Output Voltage V
IN
= GND LMV1015-15 4.34
4.28
4.56 4.74
4.80 V
LMV1015-25 4.45
4.39
4.65 4.83
4.86
f
LOW
Lower −3dB Roll Off Frequency R
SOURCE
=50Ω67 Hz
f
HIGH
Upper −3dB Roll Off Frequency R
SOURCE
=50Ω150 kHz
e
n
Output Noise A-Weighted LMV1015-15 −89 dBV
LMV1015-25 −82
THD Total Harmonic Distortion f = 1 kHz,
V
IN
=18mV
PP
LMV1015-15 0.13 %
LMV1015-25 0.21
C
IN
Input Capacitance 2pF
Z
IN
Input Impedance >1000 GΩ
A
V
Gain f = 1 kHz,
R
SOURCE
=50Ω
LMV1015-15 14.0
13.1
15.6 16.9
17.5 dB
LMV1015-25 22.5
21.2
23.9 25.1
25.9
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: Human Body Model (HBM) is 1.5 kΩin series with 100 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 TJ=T
A. No guarantee of parametric performance is indicated in the electrical tables under conditions of internal self-heating where TJ>TA.
Note 4: All limits are guaranteed by design or statistical analysis.
Note 5: Typical values represent the most likely parametric norm.
Note 6: The maximum power dissipation is a function of TJ(MAX),θJA and TA. The maximum allowable power dissipation at any ambient temperature is
PD=(T
J(MAX) -T
A)/θJA. All numbers apply for packages soldered directly into a PC board.
LMV1015 Analog Series
www.national.com3
Connection Diagram
Large Dome 4-Bump micro SMD
20128903
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 Extreme Thin
micro SMD
(0.3 mm max height)
lead free only
LMV1015XR-15
Date Code
250 Units Tape and Reel
XRA04ADA
LMV1015XRX-15 3k Units Tape and Reel
LMV1015XR-25 250 Units Tape and Reel
LMV1015XRX-25 3k Units Tape and Reel
4-Bump Ultra-Thin
micro SMD
(0.4 mm max height)
lead free only
LMV1015UR-15
Date Code
250 Units Tape and Reel
URA04ADA
LMV1015URX-15 3k Units Tape and Reel
LMV1015UR-25 250 Units Tape and Reel
LMV1015URX-25 3k Units Tape and Reel
Note: All packages are supplied with large dome bump technology for 1kg adhesion criteria.
LMV1015 Analog Series
www.national.com 4
Typical Performance Characteristics Unless otherwise specified, V
S
= 2.2V, R
L
= 2.2 kΩ,
C = 2.2 µF, single supply, T
A
= 25˚C
Supply Current vs. Supply Voltage (LMV1015-15) Supply Current vs. Supply Voltage (LMV1015-25)
20128904 20128919
Gain and Phase vs. Frequency (LMV1015-15) Gain and Phase vs. Frequency (LMV1015-25)
20128905 20128913
Total Harmonic Distortion vs. Frequency (LMV1015-15) Total Harmonic Distortion vs. Frequency (LMV1015-25)
20128906 20128921
LMV1015 Analog Series
www.national.com5
Typical Performance Characteristics Unless otherwise specified, V
S
= 2.2V, R
L
= 2.2 kΩ,
C = 2.2 µF, single supply, TA= 25˚C (Continued)
Total Harmonic Distortion vs. Input Voltage
(LMV1015-15)
Total Harmonic Distortion vs. Input Voltage
(LMV1015-25)
20128907 20128923
Output Noise vs. Frequency (LMV1015-15) Output Noise vs. Frequency (LMV1015-25)
20128915 20128916
LMV1015 Analog Series
www.national.com 6
Application Section
HIGH GAIN
The LMV1015 series provides outstanding gain versus the
JFET and still maintains the same ease of implementation,
with improved gain, linearity and temperature stability. A high
gain eliminates the need for extra external components.
BUILT IN GAIN
The LMV1015 is offered in 0.3 mm height space saving
small 4-pin micro SMD packages in order to fit inside the
different size ECM canisters of a microphone. The LMV1015
is placed on the PCB inside the microphone using Large
Dome Bump technology (LDB).
The bottom side of the PCB usually shows a bull’s eye
pattern where the outer ring, which is shorted to the metal
can, should be connected to the ground. The center dot on
the PCB is connected to the V
DD
through a resistor. This
phantom biasing allows both supply voltage and output sig-
nal on one connection.
A-WEIGHTED FILTER
The human ear has a frequency range from 20 Hz to about
20 kHz. Within this range the sensitivity of the human ear is
not equal for each frequency. To approach the hearing re-
sponse weighting filters are introduced. One of those filters
is the A-weighted filter.
The A-weighted filter is usually used in signal to noise ratio
measurements, where sound is compared to device noise.
This filter improves the correlation of the measured data to
the signal to noise ratio perceived by the human ear.
MEASURING NOISE AND SNR
The overall noise of the LMV1015 is measured within the
frequency band from 10 Hz to 22 kHz using an A-weighted
filter. The input of the LMV1015 is connected to ground with
a 5 pF capacitor, as in Figure 3. Special precautions in the
internal structure of the LMV1015 have been taken to reduce
the noise on the output.
The signal to noise ratio (SNR) is measured witha1kHz
input signal of 18 mV
PP
using an A-weighted filter. This
represents a sound pressure level of 94 dB SPL. No input
capacitor is connected for the measurement.
SOUND PRESSURE LEVEL
The volume of sound applied to a microphone is usually
stated as a pressure level referred to the threshold of hear-
ing of the human ear. The sound pressure level (SPL) in
decibels is defined by:
Sound pressure level (dB) = 20 log P
m
/P
O
Where,
P
m
is the measured sound pressure
P
O
is the threshold of hearing (20 µPa)
In order to be able to calculate the resulting output voltage of
the microphone for a given SPL, the sound pressure in dB
20128902
FIGURE 1. Built in Gain
20128909
FIGURE 2. A-Weighted Filter
20128910
FIGURE 3. Noise Measurement Setup
LMV1015 Analog Series
www.national.com7
Application Section (Continued)
SPL needs to be converted to the absolute sound pressure
in dBPa. This is the sound pressure level in decibels referred
to 1 Pascal (Pa).
The conversion is given by:
dBPa = dB SPL + 20*log 20 µPa
dBPa=dBSPL-94dB
Translation from absolute sound pressure level to a voltage
is specified by the sensitivity of the microphone. A conven-
tional microphone has a sensitivity of -44 dBV/Pa.
Example: Busy traffic is 70 dB SPL
V
OUT
= 70 −94 −44 = −68 dBV
This is equivalent to 1.13 mV
PP
Since the LMV1015-15 has a gain of 6 (15.6 dB) over the
JFET, the output voltage of the microphone is 6.78 mV
PP
.By
implementing the LMV1015-15, the sensitivity of the micro-
phone is −28.4 dBV/Pa (−44 + 15.6).
LOW FREQUENCY CUT OFF FILTER
To reduce noise on the output of the microphone a low
frequency cut off filter has been implemented. This filter
reduces the effect of wind and handling noise.
It’s also helpful to reduce the proximity effect in directional
microphones. This effect occurs when the sound source is
very close to the microphone. The lower frequencies are
amplified which gives a bass sound. This amplification can
cause an overload, which results in a distortion of the signal.
The LMV1015 is optimized to be used in audio band appli-
cations. By using the LMV1015, the gain response is flat
within the audio band and has linearity and temperature
stability Figure 5.
NOISE
Noise pick-up by a microphone in cell phones is a well-
known problem. A conventional JFET circuit is sensitive for
noise pick-up because of its high output impedance, which is
usually around 2.2 kΩ.
RF noise is amongst other caused by non-linear behavior.
The non-linear behavior of the amplifier at high frequencies,
well above the usable bandwidth of the device, causes AM-
demodulation of high frequency signals. The AM modulation
contained in such signals folds back into the audio band,
thereby disturbing the intended microphone signal. The
GSM signal of a cell phone is such an AM-modulated signal.
The modulation frequency of 216 Hz and its harmonics can
be observed in the audio band. This kind of noise is called
bumblebee noise.
RF noise caused by a GSM signal can be reduced by
connecting two external capacitors to ground, see Figure 6.
One capacitor reduces the noise caused by the 900 MHz
carrier and the other reduces the noise caused by 1800/
1900 MHz.
20128911
FIGURE 4. dB SPL to dBV Conversion
20128912
FIGURE 5. LMV1015-15 Gain vs. Frequency Over
Temperature
LMV1015 Analog Series
www.national.com 8
Application Section (Continued)
20128908
FIGURE 6. RF Noise Reduction
LMV1015 Analog Series
www.national.com9
Physical Dimensions inches (millimeters) unless otherwise noted
NOTE: UNLESS OTHERWISE SPECIFIED.
1. FOR SOLDER BUMP COMPOSITION, SEE "SOLDER INFORMATION" IN THE PACKAGING SECTION OF THE NATIONAL SEMICONDUCTOR WEB
PAGE (www.national.com).
2. RECOMMEND NON-SOLDER MASK DEFINED LANDING PAD.
3. PIN A1 IS ESTABLISHED BY LOWER LEFT CORNER WITH RESPECT TO TEXT ORIENTATION.
4. XXX IN DRAWING NUMBER REPRESENTS PACKAGE SIZE VARIATION WHERE X1 IS PACKAGE WIDTH, X2 IS PACKAGE LENGTH AND X3 IS
PACKAGE HEIGHT.
5. REFERENCE JEDEC REGISTRATION MO-211. VARIATION CA.
4-Bump Extreme Thin micro SMD with Large Dome Bump Technology
NS Package Number XRA04ADA
X
1
= 0.975 mm X
2
= 1.051 mm X
3
= 0.300 mm
NOTE: UNLESS OTHERWISE SPECIFIED.
1. FOR SOLDER BUMP COMPOSITION, SEE "SOLDER INFORMATION" IN THE PACKAGING SECTION OF THE NATIONAL SEMICONDUCTOR WEB
PAGE (www.national.com).
2. RECOMMEND NON-SOLDER MASK DEFINED LANDING PAD.
3. PIN A1 IS ESTABLISHED BY LOWER LEFT CORNER WITH RESPECT TO TEXT ORIENTATION.
4. XXX IN DRAWING NUMBER REPRESENTS PACKAGE SIZE VARIATION WHERE X1 IS PACKAGE WIDTH, X2 IS PACKAGE LENGTH AND X3 IS
PACKAGE HEIGHT.
5. NO JEDEC REGISTRATION AS OF March 2005.
4-Bump ULTRA-Thin micro SMD with Large Dome Bump Technology
NS Package Number URA04ADA
X
1
= 0.975 mm X
2
= 1.051 mm X
3
= 0.400 mm
LMV1015 Analog Series
www.national.com 10
Notes
National does not assume any responsibility for use of any circuitry described, no circuit patent licenses are implied and National reserves
the right at any time without notice to change said circuitry and specifications.
For the most current product information visit us at www.national.com.
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2. A critical component is any component of a life support
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LMV1015 Analog Series Built-in Gain IC’s for High Sensitivity 2-Wire Microphones
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