LMV1032-06/LMV1032-15/LMV1032-25 Amplifiers for 3 Wire Analog Electret Microphones General Description Features The LMV1032 is an audio amplifier series for small form factor electret microphones. It is 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 in electret microphones that incorporate the 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 LMV1032-06, 1.7V Supply; Unless Otherwise Noted) n Output voltage noise (A-weighted) −97 dBV n Low supply current 60 µA n Supply voltage 1.7V to 5V n PSRR 84 dB n Signal to noise ratio 58 dB n Input capacitance 2 pF > 100 MΩ n Input impedance < 200Ω n Output impedance n Max input signal 300 mVPP n Temperature range −40˚C to 85˚C n Offered in 1.13 x 1.13 x 0.4mm Ultra Thin micro SMD lead free (NOPB) package 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 package and are thus ideally suited for the form factor of miniature electret microphone packages. Block Diagram Applications n n n n n Mobile communications - Bluetooth Automotive accessories Cellular phones PDAs Accessory microphone products Electret Microphone 20084202 20084201 © 2004 National Semiconductor Corporation DS200842 www.national.com LMV1032-06/LMV1032-15/LMV1032-25 Amplifiers for 3 Wire Analog Electret Microphones February 2004 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 f = 1kHz and THD+N < 1% fLOW Lower −3 dB Roll Off Frequency RSOURCE = 50Ω VIN = 18 mVPP fHIGH Upper −3 dB Roll Off Frequency RSOURCE = 50Ω VIN = 18 mVPP en Output Noise LMV1032-25 62 LMV1032-06 300 LMV1032-15 170 LMV1032-25 60 LMV1032-06 120 LMV1032-15 75 LMV1032-25 21 LMV1032-06 −97 LMV1032-15 −89 LMV1032-25 VOUT 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 µA dB 70 A-Weighted 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: Human Body Model (HBM) is 1.5 kΩ in 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 = 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 into 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 4-Bump Ultra Thin 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 LMV1032UP-06 LMV1032UPX-06 4-Bump Ultra Thin micro SMD lead free LMV1032UP-15 LMV1032UPX-15 LMV1032UP-25 LMV1032UPX-25 Package Marking Date Code Date Code Date Code Note: The LMV1032 series is offered only with lead free (NOPB) solder bumps. The LMV1032 series replaces the LMV1014. www.national.com 4 Transport Media NSC Drawing 250 Units Tape and Reel 3k Units Tape and Reel 250 Units Tape and Reel 3k Units Tape and Reel 250 Units Tape and Reel 3k Units Tape and Reel UPA04QQA 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 (LMV1036-06) 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 LOW CURRENT The LMV1032 has low supply current for a longer battery life. The low supply current makes this amplifier suitable for microphone applications which need to be always on. BUILT IN GAIN The LMV1032 is offered in space saving small micro SMD package in order to fit in the metal can of a microphone. The LMV1032 is 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 inside the metal can via the PCB to the microphone. 20084209 FIGURE 2. A-Weighted Filter 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. 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 signal to noise ratio perceived by the human ear. 20084210 FIGURE 3. Noise Measurement Setup 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 a pressure level referred 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 referred to 1 Pascal (Pa). www.national.com 8 LMV1032-06/LMV1032-15/LMV1032-25 Application Section (Continued) The conversion is given by: dBPa = dB SPL + 20*log 20 µPa dBPa = dB SPL - 94 dB 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. 20084212 FIGURE 5. Gain vs. Frequency Over Temperature The LMV1032 is optimized to be used in audio band applications. By using the LMV1032, the gain response is flat within the audio band and has the linearity and temperature stability. ADVANTAGE OF THREE PINS The LMV1032 has three pins instead of two pins as in the case of a JFET solution. The third pin brings 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 separating the output pin and the positive supply pin a much lower output impedance is achieved. The output of the LMV1032 is therefore less sensitive to noise pick-up. 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 AMdemodulation 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. 20084211 FIGURE 4. dB SPL to dBV Conversion Example: Busy traffic is 70 dB SPL VOUT = 70 −94 −44 = −68 dBV This is equivalent to 1.13 mVPP Since the LMV1032-06 has a gain of 2 (6 dB) over the JFET, the output voltage of the microphone is 2.26 mVPP. By implementing the LMV1032-06, the sensitivity of the microphone is −38 dBV/Pa (−44 + 6). LOW FREQUENCY CUT OFF FILTER To reduce noise on the output of the microphone a low cut 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. 9 www.national.com LMV1032-06/LMV1032-15/LMV1032-25 Physical Dimensions inches (millimeters) unless otherwise noted NOTE: UNLESS OTHERWISE SPECIFIED. 1. TITANIUM COATING. 2. FOR SOLDER BUMP COMPOSITION, SEE "SOLDER INFORMATION" IN THE PACKAGING SECTION OF THE NATIONAL SEMICONDUCTOR WEB PAGE (www.national.com). 3. RECOMMEND NON-SOLDER MASK DEFINED LANDING PAD. 4. PIN A1 IS ESTABLISHED BY LOWER LEFT CORNER WITH RESPECT TO TEXT ORIENTATION. 5. XXX IN DRAWING NUMBER REPRESENTS PACKAGE SIZE VARIATION WHERE X1 IS PACKAGE WIDTH, X2 IS PACKAGE LENGTH AND X3 IS PACKAGE HEIGHT. 6. REFERENCE JEDEC REGISTRATION MO-211. VARIATION BC. 4-Bump Ultra Thin micro SMD NS Package Number UPA04QQA X1 = 1.133mm X2 = 1.133mm X3 = 0.4mm www.national.com 10 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. Life support devices or systems are devices or systems which, (a) are intended for surgical implant into the body, or (b) support or sustain life, and whose failure to perform when properly used in accordance with instructions for use provided in the labeling, can be reasonably expected to result in a significant injury to the user. 2. A critical component is any component of a life support device or system whose failure to perform can be reasonably expected to cause the failure of the life support device or system, or to affect its safety or effectiveness. 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