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 Features 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 allows for a dramatic reduction in supply current as compared to the JFET equipped electret microphone. Microphone supply 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. (Typical LMV1032-15, 1.7V Supply; Unless Otherwise Noted) n Output voltage noise (A-weighted) −89 dBV n Low supply current 60 µA n Supply voltage 1.7V to 5V n PSRR 70 dB n Signal to noise ratio 61 dB n Input capacitance 2 pF > 100 MΩ n Input impedance < 200Ω n Output impedance n Max input signal 170 mVPP n Temperature range −40˚C to 85˚C n Large Dome 4-Bump micro SMD package with improved adhesion technology. 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 technology is designed for microphone PCBs requiring 1 kg adhesion criteria. Block Diagram Applications n n n n n Mobile communications - Bluetooth Automotive accessories Cellular phones PDAs Accessory microphone products Electret Microphone 20084202 20084201 © 2005 National Semiconductor Corporation DS200842 www.national.com LMV1032-06/LMV1032-15/LMV1032-25 Amplifiers for 3-Wire Analog Electret Microphones November 2005 LMV1032-06/LMV1032-15/LMV1032-25 Absolute Maximum Ratings (Note 1) Storage Temperature Range If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications. Junction Temperature (Note 6) −65˚C to 150˚C 150˚C max Mounting Temperature Infrared or Convection (20 sec.) 235˚C ESD Tolerance (Note 2) Human Body Model 2500V Machine Model Operating Ratings (Note 1) 250V Supply Voltage Supply Voltage VDD - GND 1.7V to 5V Temperature Range 5.5V −40˚C to +85˚C 1.7V and 5V Electrical Characteristics (Note 3) Unless otherwise specified, all limits guaranteed for TJ = 25˚C and VDD = 1.7V and 5V. Boldface limits apply at the temperature extremes. Symbol Parameter Min (Note 4) Conditions Typ (Note 5) Max (Note 4) 60 85 100 IDD Supply Current VIN = GND SNR Signal to Noise Ratio VDD = 1.7V VIN = 18 mVPP f = 1 kHz LMV1032-06 58 LMV1032-15 61 LMV1032-25 61 VDD = 5V VIN = 18 mVPP f = 1 kHz LMV1032-06 59 LMV1036-15 61 1.7V < VDD < 5V LMV1032-06 65 60 75 LMV1032-15 60 55 70 LMV1032-25 55 50 65 PSRR VIN Power Supply Rejection Ratio Max Input Signal LMV1032-25 f = 1 kHz and THD+N < 1% LMV1032-06 300 LMV1032-15 170 LMV1032-25 60 Lower −3 dB Roll Off Frequency RSOURCE = 50Ω VIN = 18 mVPP fHIGH Upper −3 dB Roll Off Frequency RSOURCE = 50Ω VIN = 18 mVPP LMV1032-06 120 LMV1032-15 75 LMV1032-25 21 A-Weighted LMV1032-06 −97 LMV1032-15 −89 Output Noise Output Voltage VIN = GND dB mVPP kHz dBV −80 100 300 500 LMV1032-15 250 500 750 LMV1032-25 300 600 1000 < 200 Output Impedance f = 1 kHz IO Output Current VDD = 1.7V, VOUT = 1.7V, Sinking 0.9 0.5 2.3 VDD = 1.7V, VOUT = 0V, Sourcing 0.3 0.2 0.64 VDD = 5V, VOUT = 1.7V, Sinking 0.9 0.5 2.4 VDD = 5V, VOUT = 0V, Sourcing 0.4 0.1 1.46 2 Hz LMV1032-06 RO www.national.com dB 70 LMV1032-25 VOUT µA 62 fLOW en Units mV Ω mA (Note 3) (Continued) Unless otherwise specified, all limits guaranteed for TJ = 25˚C and VDD = 1.7V and 5V. Boldface limits apply at the temperature extremes. Symbol THD CIN Parameter Total Harmonic Distortion Min (Note 4) Conditions f = 1 kHz VIN = 18 mVPP LMV1032-06 0.11 LMV1032-15 0.13 LMV1032-25 0.35 Input Capacitance ZIN Input Impedance AV Gain Typ (Note 5) Max (Note 4) % 2 pF > 100 f = 1 kHz VIN = 18 mVPP Units MΩ LMV1032-06 5.5 4.5 6.2 6.7 7.7 LMV1032-15 14.8 14 15.4 16 17 LMV1032-25 24.8 24 25.5 26.2 27 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 kΩ in series with 100 pF. The Machine Model is 0Ω 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 TJ = TA. 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) - TA)/θJA. All numbers apply for packages soldered directly onto a PC board. 3 www.national.com LMV1032-06/LMV1032-15/LMV1032-25 1.7V and 5V Electrical Characteristics LMV1032-06/LMV1032-15/LMV1032-25 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 4-Bump Ultra Thin micro SMD (LDB) Lead Free LMV1032UR-15 LMV1032URX-15 LMV1032UR-25 LMV1032URX-25 LMV1032UP-06 4-Bump Ultra Thin micro SMD (Small Bump) Lead Free LMV1032UPX-06 LMV1032UP-15 LMV1032UPX-15 LMV1032UP-25 LMV1032UPX-25 Package Marking Transport Media 250 Units Tape and Reel Date Code 3k Units Tape and Reel 250 Units Tape and Reel Date Code Full Production Full Production 250 Units Tape and Reel Date Code Full Production 250 Units Tape and Reel 250 Units Tape and Reel Date Code 3k Units Tape and Reel 250 Units Tape and Reel Date Code 3k Units Tape and Reel The LMV1032 series replaces the LMV1014. 4 Product Status URA04JJA 3k Units Tape and Reel Note: The LMV1032 series is offered only with lead free (NOPB) solder bumps. www.national.com NSC Drawing UPA04QQA Life Time Buy Life Time Buy Unless otherwise specified, VS = 1.7V, single supply, TA = Supply Current vs. Supply Voltage (LMV1032-06) Supply Current vs. Supply Voltage (LMV1032-15) 20084204 20084213 Closed Loop Gain and Phase vs. Frequency (LMV1032-06) Supply Current vs. Supply Voltage (LMV1032-25) 20084205 20084214 Closed Loop Gain and Phase vs. Frequency (LMV1032-15) Closed Loop Gain and Phase vs. Frequency (LMV1032-25) 20084216 20084215 5 www.national.com LMV1032-06/LMV1032-15/LMV1032-25 Typical Performance Characteristics 25˚C LMV1032-06/LMV1032-15/LMV1032-25 Typical Performance Characteristics Unless otherwise specified, VS = 1.7V, single supply, TA = 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) 20084207 20084218 Total Harmonic Distortion vs. Frequency (LMV1032-15) Total Harmonic Distortion vs. Frequency (LMV1032-25) 20084219 www.national.com 20084220 6 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) 20084223 20084222 Output Voltage Noise vs. Frequency (LMV1032-15) Output Voltage Noise vs. Frequency (LMV1032-25) 20084224 20084225 7 www.national.com LMV1032-06/LMV1032-15/LMV1032-25 Typical Performance Characteristics Unless otherwise specified, VS = 1.7V, single supply, TA = 25˚C (Continued) LMV1032-06/LMV1032-15/LMV1032-25 Application Section 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. 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 available. The input of the amplifier is connected to the microphone via the PCB. 20084210 FIGURE 3. Noise Measurement Setup The signal-to-noise ratio (SNR) is measured with a 1 kHz input signal of 18 mVPP 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 Pm/PO Where, Pm is the measured sound pressure PO 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 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 response 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 signalto-noise ratio perceived by the human ear. 20084209 FIGURE 2. A-Weighted Filter www.national.com 8 (Continued) The LMV1032 is optimized to be used in audio band applications. The LMV1032 provides a flat gain response within the audio band and offers linearity and excellent temperature stability. The conversion is given by: dBPa = dB SPL + 20*log 20 µPa dBPa = dB SPL - 94 dB 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 wellknown 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 impedance is achieved and therefore is less sensitive to noise pick-up. Translation from absolute sound pressure level to a voltage is specified by the sensitivity of the microphone. A conventional microphone has a sensitivity of −44 dBV/Pa. 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 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 type of noise is called bumblebee noise. 20084211 FIGURE 4. dB SPL to dBV Conversion 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 microphone are the additional gain and the high pass filter supplied by the LMV1032. The high pass filter makes the output signal more robust and less sensitive to low frequency disturbances. In this configuration the LMV1032 should be placed as close as possible to the microphone. Example: Busy traffic is 70 dB SPL VOUT = 70 −94 −44 = −68 dBV This is equivalent to 1.13 mVPP Since the LMV1032-15 has a gain of 5.6 (15 dB) over the JFET, the output voltage of the microphone is 6.35 mVPP. 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. 20084226 FIGURE 6. LMV1032 as External Pre-Amplifier 20084215 FIGURE 5. Gain vs. Frequency 9 www.national.com LMV1032-06/LMV1032-15/LMV1032-25 Application Section LMV1032-06/LMV1032-15/LMV1032-25 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 www.national.com 10 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. LIFE SUPPORT POLICY NATIONAL’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT AND GENERAL COUNSEL OF NATIONAL SEMICONDUCTOR CORPORATION. As used herein: 1. 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