LMV1032UR-25/NOPB - NATIONAL SEMICONDUCTOR

LMV1032

LMV1032-06/LMV1032-15/LMV1032-25 Amplifiers for 3-Wire Analog Electret

Microphones

Literature Number: SNAS233F

LMV1032-06/LMV1032-15/LMV1032-25

Amplifiers for 3-Wire Analog Electret Microphones

General Description

The LMV1032s are an audio amplifier series for small form

factor electret microphones. They are designed to replace

the JFET preamp currently being used. The LMV1032 series

is ideal for extended battery life applications, such as a

Bluetooth communication link. The addition of a third pin to

an electret microphones that incorporates an LMV1032 al-

lows for a dramatic reduction in supply current as compared

to the JFET equipped electret microphone. Microphone sup-

ply current is thus reduced to 60 µA, assuring longer battery

life. The LMV1032 series is guaranteed for supply voltages

from 1.7V to 5V, and has fixed voltage gains of 6 dB, 15 dB

and 25 dB.

The LMV1032 series offers low output impedance over the

voice bandwidth, excellent power supply rejection (PSRR),

and stability over temperature.

The devices are offered in space saving 4-bump ultra thin

micro SMD (TM) lead free packages and are thus ideally

suited for the form factor of miniature electret microphone

packages. These extremely miniature packages have the

Large Dome Bump (LDB) technology. This micro SMD tech-

nology is designed for microphone PCBs requiring 1 kg

adhesion criteria.

Features

(Typical LMV1032-15, 1.7V Supply; Unless Otherwise

Noted)

nOutput voltage noise (A-weighted) −89 dBV

nLow supply current 60 µA

nSupply voltage 1.7V to 5V

nPSRR 70 dB

nSignal to noise ratio 61 dB

nInput capacitance 2 pF

nInput impedance >100 MΩ

nOutput impedance <200Ω

nMax input signal 170 mV

nTemperature range −40˚C to 85˚C

nLarge Dome 4-Bump micro SMD package with improved

adhesion technology.

Applications

nMobile communications - Bluetooth

nAutomotive accessories

nCellular phones

nPDAs

nAccessory microphone products

Block Diagram

20084201

Electret Microphone

20084202

November 2005

LMV1032-06/LMV1032-15/LMV1032-25 Amplifiers for 3-Wire Analog Electret Microphones

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

- 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 1.7V to 5V

Temperature Range −40˚C to +85˚C

1.7V and 5V Electrical Characteristics (Note 3)

Unless otherwise specified, all limits guaranteed for T

= 25˚C and V

= 1.7V and 5V. Boldface limits apply at the tempera-

ture extremes.

Symbol Parameter Conditions

Min

(Note 4)

Typ

(Note 5)

Max

(Note 4) Units

Supply Current V

= GND 60 85

100 µA

SNR Signal to Noise Ratio V

= 1.7V

=18mV

f=1kHz

LMV1032-06 58

LMV1032-15 61

LMV1032-25 61

=5V

=18mV

f=1kHz

LMV1032-06 59

LMV1036-15 61

LMV1032-25 62

PSRR Power Supply Rejection Ratio 1.7V <V

<5V LMV1032-06 65

LMV1032-15 60

LMV1032-25 55

Max Input Signal f = 1 kHz and THD+N

<1%

LMV1032-06 300

LMV1032-15 170

LMV1032-25 60

LOW

Lower −3 dB Roll Off Frequency R

SOURCE

=50Ω

=18mV

70 Hz

HIGH

Upper −3 dB Roll Off Frequency R

SOURCE

=50Ω

=18mV

LMV1032-06 120 kHz

LMV1032-15 75

LMV1032-25 21

Output Noise A-Weighted LMV1032-06 −97

dBVLMV1032-15 −89

LMV1032-25 −80

OUT

Output Voltage V

= GND LMV1032-06 100 300 500

mVLMV1032-15 250 500 750

LMV1032-25 300 600 1000

Output Impedance f=1kHz <200 Ω

Output Current V

= 1.7V, V

OUT

= 1.7V, Sinking 0.9

0.5

2.3

= 1.7V, V

OUT

= 0V, Sourcing 0.3

0.2

0.64

= 5V, V

OUT

= 1.7V, Sinking 0.9

0.5

2.4

= 5V, V

OUT

= 0V, Sourcing 0.4

0.1

1.46

LMV1032-06/LMV1032-15/LMV1032-25

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1.7V and 5V Electrical Characteristics (Note 3) (Continued)

Unless otherwise specified, all limits guaranteed for T

= 25˚C and V

= 1.7V and 5V. Boldface limits apply at the tempera-

ture extremes.

Symbol Parameter Conditions

Min

(Note 4)

Typ

(Note 5)

Max

(Note 4) Units

THD Total Harmonic Distortion f=1kHz

=18mV

LMV1032-06 0.11

%LMV1032-15 0.13

LMV1032-25 0.35

Input Capacitance 2pF

Input Impedance >100 MΩ

Gain f=1kHz

=18mV

LMV1032-06 5.5

4.5

6.2 6.7

7.7

LMV1032-15 14.8

15.4 16

LMV1032-25 24.8

25.5 26.2

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 kΩin series with 100 pF. The Machine Model is 0Ωin 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 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=

(TJ(MAX) -T

A)/θJA. All numbers apply for packages soldered directly onto a PC board.

LMV1032-06/LMV1032-15/LMV1032-25

www.national.com3

Connection Diagram

Large Dome 4-Bump micro SMD

20084203

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 Product Status

4-Bump

Ultra Thin micro SMD

(LDB)

Lead Free

LMV1032UR-15 Date Code 250 Units Tape and Reel

URA04JJA

Full Production

LMV1032URX-15 3k Units Tape and Reel

LMV1032UR-25 Date Code 250 Units Tape and Reel Full Production

LMV1032URX-25 3k Units Tape and Reel

4-Bump

Ultra Thin micro SMD

(Small Bump)

Lead Free

LMV1032UP-06 Date Code 250 Units Tape and Reel

UPA04QQA

Full Production

LMV1032UPX-06 250 Units Tape and Reel

LMV1032UP-15 Date Code 250 Units Tape and Reel Life Time Buy

LMV1032UPX-15 3k Units Tape and Reel

LMV1032UP-25 Date Code 250 Units Tape and Reel Life Time Buy

LMV1032UPX-25 3k Units Tape and Reel

Note: The LMV1032 series is offered only with lead free (NOPB) solder bumps.

The LMV1032 series replaces the LMV1014.

LMV1032-06/LMV1032-15/LMV1032-25

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Typical Performance Characteristics Unless otherwise specified, V

= 1.7V, single supply, T

25˚C

Supply Current vs. Supply Voltage (LMV1032-06) Supply Current vs. Supply Voltage (LMV1032-15)

20084204 20084213

Supply Current vs. Supply Voltage (LMV1032-25)

Closed Loop Gain and Phase vs. Frequency

(LMV1032-06)

20084214 20084205

Closed Loop Gain and Phase vs. Frequency

(LMV1032-15)

Closed Loop Gain and Phase vs. Frequency

(LMV1032-25)

20084215 20084216

LMV1032-06/LMV1032-15/LMV1032-25

www.national.com5

Typical Performance Characteristics Unless otherwise specified, V

= 1.7V, single supply, T

25˚C (Continued)

Power Supply Rejection Ratio vs. Frequency

(LMV1032-06)

Power Supply Rejection Ratio vs. Frequency

(LMV1032-15)

20084206 20084217

Power Supply Rejection Ratio vs. Frequency

(LMV1032-25) Total Harmonic Distortion vs. Frequency (LMV1032-06)

20084218 20084207

Total Harmonic Distortion vs. Frequency (LMV1032-15) Total Harmonic Distortion vs. Frequency (LMV1032-25)

20084219 20084220

LMV1032-06/LMV1032-15/LMV1032-25

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Typical Performance Characteristics Unless otherwise specified, V

= 1.7V, single supply, T

25˚C (Continued)

Total Harmonic Distortion vs. Input Voltage

(LMV1032-06)

Total Harmonic Distortion vs. Input Voltage

(LMV1032-15)

20084208 20084221

Total Harmonic Distortion vs. Input Voltage

(LMV1032-25) Output Voltage Noise vs. Frequency (LMV1032-06)

20084222 20084223

Output Voltage Noise vs. Frequency (LMV1032-15) Output Voltage Noise vs. Frequency (LMV1032-25)

20084224 20084225

LMV1032-06/LMV1032-15/LMV1032-25

www.national.com7

Application Section

LOW CURRENT

The LMV1032 has a low supply current which allows for a

longer battery life. The low supply current of 60µA makes this

amplifier optimal for microphone applications which need to

be always on.

BUILT-IN GAIN

The LMV1032 is offered in the space saving small micro

SMD package which fits perfectly into the metal can of a

microphone. This allows the LMV1032 to be placed on the

PCB inside the microphone.

The bottom side of the PCB has the pins that connect the

supply voltage to the amplifier and make the output avail-

able. The input of the amplifier is connected to the micro-

phone via the PCB.

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. It

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 LMV1032 is measured within the

frequency band from 10 Hz to 22 kHz using an A-weighted

filter. The input of the LMV1032 is connected to ground with

a 5 pF capacitor.

The signal-to-noise ratio (SNR) is measured witha1kHz

input signal of 18 mV

using an A-weighted filter. This

represents a sound pressure level of 94 dB SPL. No input

capacitor is connected.

SOUND PRESSURE LEVEL

The volume of sound applied to a microphone is usually

stated as the pressure level with respect to the threshold of

hearing of the human ear. The sound pressure level (SPL) in

decibels is defined by:

Sound pressure level (dB) = 20 log P

Where,

is the measured sound pressure

is the threshold of hearing (20µPa)

In order to be able to calculate the resulting output voltage of

the microphone for a given SPL, the sound pressure in dB

SPL needs to be converted to the absolute sound pressure

in dBPa. This is the sound pressure level in decibels which is

referred to as 1 Pascal (Pa).

20084202

FIGURE 1. Built-in Gain

20084209

FIGURE 2. A-Weighted Filter

20084210

FIGURE 3. Noise Measurement Setup

LMV1032-06/LMV1032-15/LMV1032-25

www.national.com 8

Application Section (Continued)

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

OUT

= 70 −94 −44 = −68 dBV

This is equivalent to 1.13 mV

Since the LMV1032-15 has a gain of 5.6 (15 dB) over the

JFET, the output voltage of the microphone is 6.35 mV

.By

replacing the JFET with the LMV1032-15, the sensitivity of

the microphone is −29 dBV/Pa (−44 + 15).

LOW FREQUENCY CUT OFF FILTER

To reduce noise on the output of the microphone a low cut

filter has been implemented in the LMV1032. 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 LMV1032 is optimized to be used in audio band appli-

cations. The LMV1032 provides a flat gain response within

the audio band and offers linearity and excellent temperature

stability.

ADVANTAGE OF THREE PINS

The LMV1032 ECM solution has three pins instead of the

two pins provided in the case of a JFET solution. The third

pin provides the advantage of a low supply current, high

PSRR and eliminates the need for additional components.

Noise pick-up by a microphone in a cell phone is a well-

known problem. A conventional JFET circuit is sensitive for

noise pick-up because of its high output impedance. The

output impedance is usually around 2.2 kΩ. By providing

separate output and supply pins a much lower output imped-

ance is achieved and therefore is less sensitive to noise

pick-up.

RF noise is among 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 de-

modulation 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 type of noise is called

bumblebee noise.

EXTERNAL PRE-AMPLIFIER APPLICATION

The LMV1032 can also be used outside of an ECM as a

space saving external pre-amplifier. In this application, the

LMV1032 follows a phantom biased JFET microphone in the

circuit. This is shown in Figure 6. The input of the LMV1032

is connected to the microphone via the 2.2 µF capacitor. The

advantage of this circuit over one with only a JFET micro-

phone are the additional gain and the high pass filter sup-

plied by the LMV1032. The high pass filter makes the output

signal more robust and less sensitive to low frequency dis-

turbances. In this configuration the LMV1032 should be

placed as close as possible to the microphone.

20084211

FIGURE 4. dB SPL to dBV Conversion

20084215

FIGURE 5. Gain vs. Frequency

20084226

FIGURE 6. LMV1032 as External Pre-Amplifier

LMV1032-06/LMV1032-15/LMV1032-25

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. NO JEDEC REGISTRATION AS OF MAY 2005.

4-Bump Ultra Thin micro SMD with Large Dome Bump Technology

NS Package Number URA04JJA

X1 = 1.179 ±0.030 mm X2 = 1.179 ±0.030 mm X3 = 0.35 ±0.075 mm

LMV1032-06/LMV1032-15/LMV1032-25

www.national.com 10

Physical Dimensions inches (millimeters) unless otherwise noted (Continued)

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 Ultra Thin micro SMD

NS Package Number UPA04QQA

X1 = 1.133 ±0.03 mm X2 = 1.133 ±0.03 mm X3 = 0.35 ±0.045 mm

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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LMV1032-06/LMV1032-15/LMV1032-25 Amplifiers for 3-Wire Analog Electret Microphones

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