LMV1012 Analog Series: Pre-Amplified IC’s for High Gain 2-Wire Microphones General Description Features The LMV1012 is an audio amplifier series for small form factor electret microphones. This 2-wire portfolio is designed to replace the JFET amplifier currently being used. The LMV1012 series is ideally suited for applications requiring high signal integrity in the presence of ambient or RF noise, such as in cellular communications. The LMV1012 audio amplifiers are guaranteed to operate over a 2.2V to 5.0V supply voltage range with fixed gains of 7.8 dB, 15.6 dB, 20.9 dB, and 23.8 dB. The devices offer excellent THD, gain accuracy and temperature stability as compared to a JFET microphone. (Typical LMV1012-15, 2.2V supply, RL = 2.2 kΩ, C = 2.2 µF, VIN = 18 mVPP, unless otherwise specified) n Supply voltage 2V - 5V < 180 µA n Supply current n Signal to noise ratio (A-weighted) 60 dB n Output voltage noise (A-weighted) −89 dBV n Total harmonic distortion 0.09% n Voltage gain — LMV1012-07 7.8 dB — LMV1012-15 15.6 dB — LMV1012-20 20.9 dB — LMV1012-25 23.8 dB n Temperature range −40˚C to 85˚C n Offered in 4-bump micro SMD packages The LMV1012 series enables a two-pin electret microphone solution, which provides direct pin-to-pin compatibility with the existing JFET market. The devices are offered in extremely thin space saving 4-bump micro SMD packages. The LMV1012XP is designed for 1.0 mm canisters and thicker ECM canisters. These extremely miniature packages are designed for electret condenser microphones (ECM) form factor. Schematic Diagram Applications n n n n n n Cellular phones Headsets Mobile communications Automotive accessories PDAs Accessory microphone products Built-In Gain Electret Microphone 20058702 20058701 © 2004 National Semiconductor Corporation DS200587 www.national.com LMV1012 Analog Series Pre-Amplified IC’s for High Gain 2-Wire Microphones August 2004 LMV1012 Analog Series 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 2V to 5V Temperature Range 5.5V −40˚C to 85˚C 2.2V Electrical Characteristics (Note 3) Unless otherwise specified, all limits guaranteed for TJ = 25˚C, VDD = 2.2V, VIN = 18 mV, RL = 2.2 kΩ and C = 2.2 µF. Boldface limits apply at the temperature extremes. Symbol IDD SNR VIN VOUT Parameter Supply Current Signal to Noise Ratio Max Input Signal Output Voltage Typ (Note 5) Max (Note 4) LMV1012-07 139 250 300 LMV1012-15 180 300 325 LMV1012-20 160 250 300 LMV1012-25 141 250 300 LMV1012-07 59 LMV1012-15 60 LMV1012-20 61 LMV1012-25 61 Conditions VIN = GND f = 1 kHz, VIN = 18 mV, A-Weighted f = 1 kHz and THD+N < 1% VIN = GND Min (Note 4) LMV1012-07 170 LMV1012-15 100 LMV1012-20 50 LMV1012-25 28 Units µA dB mVPP LMV1012-07 1.65 1.54 1.90 2.03 2.09 LMV1012-15 1.54 1.48 1.81 1.94 2.00 LMV1012-20 1.65 1.55 1.85 2.03 2.13 LMV1012-25 1.65 1.49 1.90 2.02 2.18 V fLOW Lower −3dB Roll Off Frequency RSOURCE = 50Ω 65 Hz fHIGH Upper −3dB Roll Off Frequency RSOURCE = 50Ω 95 kHz en Output Noise A-Weighted THD Total Harmonic Distortion CIN Input Capacitance ZIN Input Impedance www.national.com f = 1 kHz, VIN = 18 mV 2 LMV1012-07 −96 LMV1012-15 −89 LMV1012-20 −84 LMV1012-25 −82 LMV1012-07 0.10 LMV1012-15 0.09 LMV1012-20 0.12 LMV1012-25 0.15 dBV % 2 pF > 1000 GΩ (Note 3) (Continued) Unless otherwise specified, all limits guaranteed for TJ = 25˚C, VDD = 2.2V, VIN = 18 mV, RL = 2.2 kΩ and C = 2.2 µF. Boldface limits apply at the temperature extremes. Symbol AV Parameter Gain Min (Note 4) Typ (Note 5) Max (Note 4) LMV1012-07 6.4 5.5 7.8 9.5 10.0 LMV1012-15 14.0 13.1 15.6 16.9 17.5 LMV1012-20 19.5 17.4 20.9 22.0 23.3 LMV1012-25 22.5 21.4 23.8 25.0 25.7 Conditions f = 1 kHz, RSOURCE = 50Ω Units dB 5V Electrical Characteristics (Note 3) Unless otherwise specified, all limits guaranteed for TJ = 25˚C, VDD = 5V, VIN = 18 mV, RL = 2.2 kΩ and C = 2.2 µF. Boldface limits apply at the temperature extremes. Symbol IDD SNR VIN VOUT Parameter Supply Current Signal to Noise Ratio Max Input Signal Output Voltage Typ (Note 5) Max (Note 4) LMV1012-07 158 250 300 LMV1012-15 200 300 325 LMV1012-20 188 260 310 LMV1012-25 160 250 300 LMV1012-07 59 LMV1012-15 60 LMV1012-20 61 Conditions VIN = GND f = 1 kHz, VIN = 18 mV, A-Weighted f = 1 kHz and THD+N < 1% VIN = GND Min (Note 4) LMV1012-25 61 LMV1012-07 170 LMV1012-15 100 LMV1012-20 55 LMV1012-25 28 Units µA dB mVPP LMV1012-07 4.45 4.38 4.65 4.80 4.85 LMV1012-15 4.34 4.28 4.56 4.74 4.80 LMV1012-20 4.40 4.30 4.58 4.75 4.85 LMV1012-25 4.45 4.39 4.65 4.83 4.86 V fLOW Lower −3dB Roll Off Frequency RSOURCE = 50Ω 67 Hz fHIGH Upper −3dB Roll Off Frequency RSOURCE = 50Ω 150 kHz en Output Noise A-Weighted THD Total Harmonic Distortion f = 1 kHz, VIN = 18 mV 3 LMV1012-07 −96 LMV1012-15 −89 LMV1012-20 −84 LMV1012-25 −82 LMV1012-07 0.12 LMV1012-15 0.13 LMV1012-20 0.18 LMV1012-25 0.21 dBV % www.national.com LMV1012 Analog Series 2.2V Electrical Characteristics LMV1012 Analog Series 5V Electrical Characteristics (Note 3) (Continued) Unless otherwise specified, all limits guaranteed for TJ = 25˚C, VDD = 5V, VIN = 18 mV, RL = 2.2 kΩ and C = 2.2 µF. Boldface limits apply at the temperature extremes. Symbol Parameter CIN Input Capacitance ZIN Input Impedance AV Gain Conditions Min (Note 4) Typ (Note 5) Max (Note 4) 2 pF > 1000 f = 1 kHz, RSOURCE = 50Ω Units GΩ LMV1012-07 6.4 5.5 8.1 9.5 10.7 LMV1012-15 14.0 13.1 15.6 16.9 17.5 LMV1012-20 19.2 17.0 21.1 22.3 23.5 LMV1012-25 22.5 21.2 23.9 25.0 25.8 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. www.national.com 4 LMV1012 Analog Series Connection Diagram 4-Bump micro SMD 20058703 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 Extreme Thin micro SMD (0.3 mm max height) lead free only LMV1012XP-15 4-Bump Ultra-Thin micro SMD (0.4 mm max height) lead free only 4-Bump Thin micro SMD (0.5 mm max height) LMV1012XPX-15 LMV1012XP-25 Package Marking Transport Media Date Code 3k Units Tape and Reel 250 Units Tape and Reel LMV1012XPX-25 3k Units Tape and Reel LMV1012UP-07 250 Units Tape and Reel LMV1012UPX-07 3k Units Tape and Reel LMV1012UP-15 250 Units Tape and Reel LMV1012UPX-15 LMV1012UP-20 Date Code 3k Units Tape and Reel 250 Units Tape and Reel LMV1012UPX-20 3k Units Tape and Reel LMV1012UP-25 250 Units Tape and Reel LMV1012UPX-25 3k Units Tape and Reel LMV1012TP-07 250 Units Tape and Reel LMV1012TPX-07 3k Units Tape and Reel LMV1012TP-15 250 Units Tape and Reel LMV1012TPX-15 NSC Drawing 250 Units Tape and Reel Date Code 3k Units Tape and Reel LMV1012TP-25 250 Units Tape and Reel LMV1012TPX-25 3k Units Tape and Reel 5 XPA04HLA UPA04GKA TPA04GKA www.national.com LMV1012 Analog Series Typical Performance Characteristics Unless otherwise specified, VS = 2.2V, RL = 2.2 kΩ, C = 2.2 µF, single supply, TA = 25˚C Supply Current vs. Supply Voltage (LMV1012-07) Supply Current vs. Supply Voltage (LMV1012-15) 20058704 20058718 Supply Current vs. Supply Voltage (LMV1012-20) Supply Current vs. Supply Voltage (LMV1012-25) 20058719 20058724 Gain and Phase vs. Frequency (LMV1012-07) Gain and Phase vs. Frequency (LMV1012-15) 20058705 20058714 www.national.com 6 Gain and Phase vs. Frequency (LMV1012-20) Gain and Phase vs. Frequency (LMV1012-25) 20058725 20058713 Total Harmonic Distortion vs. Frequency (LMV1012-07) Total Harmonic Distortion vs. Frequency (LMV1012-15) 20058706 20058720 Total Harmonic Distortion vs. Frequency (LMV1012-20) Total Harmonic Distortion vs. Frequency (LMV1012-25) 20058726 20058721 7 www.national.com LMV1012 Analog Series Typical Performance Characteristics Unless otherwise specified, VS = 2.2V, RL = 2.2 kΩ, C = 2.2 µF, single supply, TA = 25˚C (Continued) LMV1012 Analog Series Typical Performance Characteristics Unless otherwise specified, VS = 2.2V, RL = 2.2 kΩ, C = 2.2 µF, single supply, TA = 25˚C (Continued) Total Harmonic Distortion vs. Input Voltage (LMV1012-07) Total Harmonic Distortion vs. Input Voltage (LMV1012-15) 20058707 20058722 Total Harmonic Distortion vs. Input Voltage (LMV1012-20) Total Harmonic Distortion vs. Input Voltage (LMV1012-25) 20058727 20058723 Output Noise vs. Frequency (LMV1012-07) Output Noise vs. Frequency (LMV1012-15) 20058717 www.national.com 20058715 8 Output Noise vs. Frequency (LMV1012-20) Output Noise vs. Frequency (LMV1012-25) 20058728 20058716 9 www.national.com LMV1012 Analog Series Typical Performance Characteristics Unless otherwise specified, VS = 2.2V, RL = 2.2 kΩ, C = 2.2 µF, single supply, TA = 25˚C (Continued) LMV1012 Analog Series Application Section HIGH GAIN The LMV1012 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 LMV1012 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 LMV1012 is placed on the PCB inside the microphone. 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 VDD through a resistor. This phantom biasing allows both supply voltage and output signal on one connection. 20058709 FIGURE 2. A-Weighted Filter MEASURING NOISE AND SNR The overall noise of the LMV1012 is measured within the frequency band from 10 Hz to 22 kHz using an A-weighted filter. The input of the LMV1012 is connected to ground with a 5 pF capacitor, as in Figure 3. Special precautions in the internal structure of the LMV1012 have been taken to reduce the noise on the output. 20058702 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. This filter improves the correlation of the measured data to the signal to noise ratio perceived by the human ear. 20058710 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 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 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 (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 www.national.com 10 amplified which gives a bass sound. This amplification can cause an overload, which results in a distortion of the signal. (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 = 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. 20058712 FIGURE 5. LMV1012-15 Gain vs. Frequency Over Temperature The LMV1012 is optimized to be used in audio band applications. By using the LMV1012, the gain response is flat within the audio band and has linearity and temperature stability Figure 5. NOISE 20058711 Noise pick-up by a microphone in cell phones is a wellknown 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 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. 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. 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 LMV1012-15 has a gain of 6 (15.6 dB) over the JFET, the output voltage of the microphone is 6.78 mVPP. By implementing the LMV1012-15, the sensitivity of the microphone 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 11 www.national.com LMV1012 Analog Series Application Section LMV1012 Analog Series Application Section (Continued) 20058708 FIGURE 6. RF Noise Reduction www.national.com 12 LMV1012 Analog Series 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 NS Package Number XPA04HLA X1 = 0.955 mm X2 = 1.031 mm X3 = 0.300 mm 13 www.national.com LMV1012 Analog Series Physical Dimensions inches (millimeters) unless otherwise noted (Continued) 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 CA. 4-Bump ULTRA-Thin micro SMD NS Package Number UPA04GKA X1 = 0.93 mm X2 = 1.006 mm X3 = 0.400 mm www.national.com 14 inches (millimeters) unless otherwise noted (Continued) NOTE: UNLESS OTHERWISE SPECIFIED. 1. EPOXY COATING. 2. 63Sn/37Pb EUTECTIC BUMP. 3. RECOMMEND NON-SOLDER MASK DEFINED LANDING PAD. 4. PIN A1 IS ESTABLISHED BY LOWER LEFT CORNER WITH RESPECT TO TEXT ORIENTATION PINS ARE NUMBERED COUNTERCLOCKWISE. 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 Thin micro SMD NS Package Number TPA04GKA X1 = 0.93 mm X2 = 1.006 mm X3 = 0.500 mm 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. 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