LMV1015 Analog Series: Built-in Gain IC’s for High Sensitivity 2-Wire Microphones General Description Features 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 communications. 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 excellent THD, gain accuracy and temperature stability as compared 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. (Typical LMV1015-15, 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 — LMV1015-15 15.6 dB — LMV1015-25 23.8 dB n Temperature range −40˚C to 85˚C n Large Dome 4-Bump micro SMD package with improved adhesion technology. Schematic Diagram Built-In Gain Electret Microphone Applications n n n n n n Cellular phones Headsets Mobile communications Automotive accessories PDAs Accessory microphone products 20128902 20128901 © 2005 National Semiconductor Corporation DS201289 www.national.com LMV1015 Analog Series Built-in Gain IC’s for High Sensitivity 2-Wire Microphones May 2005 LMV1015 Analog Series Absolute Maximum Ratings (Note 1) Junction Temperature (Note 6) If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications. Mounting Temperature Infrared or Convection (20 sec.) ESD Tolerance (Note 2) Human Body Model Supply Voltage 250V 2V to 5V Operating Temperature Range Supply Voltage VDD - GND −40˚C to 85˚C Thermal Resistance (θJA) 5.5V Storage Temperature Range 235˚C Operating Ratings (Note 1) 2500V Machine Model 150˚C max 368˚C/W −65˚C to 150˚C 2.2V Electrical Characteristics (Note 3) Unless otherwise specified, all limits guaranteed for TJ = 25˚C, VDD = 2.2V, VIN = 18 mVPP, RL = 2.2 kΩ and C = 2.2 µF. Boldface limits apply at the temperature extremes. Symbol IDD SNR VIN VOUT Typ (Note 5) Max (Note 4) LMV1015-15 180 300 325 LMV1015-25 141 250 300 f = 1 kHz, VIN = 18 mVPP, A-Weighted LMV1015-15 60 LMV1015-25 61 f = 1 kHz and THD+N < 1% LMV1015-15 100 LMV1015-25 28 VIN = GND LMV1015-15 1.54 1.48 1.81 1.94 2.00 LMV1015-25 1.65 1.49 1.90 2.02 2.18 Parameter Supply Current Signal to Noise Ratio Max Input Signal Output Voltage Conditions VIN = GND Min (Note 4) Units µA dB mVPP 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 CIN Total Harmonic Distortion f = 1 kHz, VIN = 18 mVPP LMV1015-15 −89 LMV1015-25 −82 LMV1015-15 0.09 LMV1015-25 0.15 Input Capacitance ZIN Input Impedance AV Gain dBV % 2 pF > 1000 f = 1 kHz, RSOURCE = 50Ω GΩ LMV1015-15 14.0 13.1 15.6 16.9 17.5 LMV1015-25 22.5 21.4 23.8 25.0 25.7 dB 5V Electrical Characteristics (Note 3) Unless otherwise specified, all limits guaranteed for TJ = 25˚C, VDD = 5V, VIN = 18 mVPP, RL = 2.2 kΩ and C = 2.2 µF. Boldface limits apply at the temperature extremes. Symbol IDD Parameter Supply Current www.national.com Typ (Note 5) Max (Note 4) LMV1015-15 200 300 325 LMV1015-25 160 250 300 Conditions VIN = GND 2 Min (Note 4) Units µA (Note 3) (Continued) Unless otherwise specified, all limits guaranteed for TJ = 25˚C, VDD = 5V, VIN = 18 mVPP, RL = 2.2 kΩ and C = 2.2 µF. Boldface limits apply at the temperature extremes. Symbol SNR VIN VOUT Parameter Signal to Noise Ratio Max Input Signal Output Voltage Conditions f = 1 kHz, VIN = 18 mVPP, A-Weighted Min (Note 4) Typ (Note 5) LMV1015-15 60 LMV1015-25 61 Max (Note 4) Units dB f = 1 kHz and THD+N < 1% LMV1015-15 100 LMV1015-25 28 VIN = GND LMV1015-15 4.34 4.28 4.56 4.74 4.80 LMV1015-25 4.45 4.39 4.65 4.83 4.86 mVPP 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 CIN Input Capacitance ZIN Input Impedance AV Gain f = 1 kHz, VIN = 18 mVPP f = 1 kHz, RSOURCE = 50Ω LMV1015-15 −89 LMV1015-25 −82 LMV1015-15 0.13 LMV1015-25 0.21 dBV % 2 pF > 1000 GΩ LMV1015-15 14.0 13.1 15.6 16.9 17.5 LMV1015-25 22.5 21.2 23.9 25.1 25.9 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 LMV1015 Analog Series 5V Electrical Characteristics LMV1015 Analog Series 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 4-Bump Extreme Thin micro SMD (0.3 mm max height) lead free only LMV1015XR-15 4-Bump Ultra-Thin micro SMD (0.4 mm max height) lead free only LMV1015XRX-15 LMV1015XR-25 Package Marking Date Code 3k Units Tape and Reel 250 Units Tape and Reel LMV1015XRX-25 3k Units Tape and Reel LMV1015UR-15 250 Units Tape and Reel LMV1015URX-15 LMV1015UR-25 Date Code LMV1015URX-25 3k Units Tape and Reel 250 Units Tape and Reel 3k Units Tape and Reel Note: All packages are supplied with large dome bump technology for 1kg adhesion criteria. www.national.com Transport Media NSC Drawing 250 Units Tape and Reel 4 XRA04ADA URA04ADA Unless otherwise specified, VS = 2.2V, RL = 2.2 kΩ, 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 5 www.national.com LMV1015 Analog Series Typical Performance Characteristics C = 2.2 µF, single supply, TA = 25˚C LMV1015 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 (LMV1015-15) Total Harmonic Distortion vs. Input Voltage (LMV1015-25) 20128907 20128923 Output Noise vs. Frequency (LMV1015-15) Output Noise vs. Frequency (LMV1015-25) 20128916 20128915 www.national.com 6 LMV1015 Analog Series 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 VDD through a resistor. This phantom biasing allows both supply voltage and output signal on one connection. 20128909 FIGURE 2. A-Weighted Filter 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. 20128902 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. 20128910 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 7 www.national.com LMV1015 Analog Series Application Section 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. 20128912 FIGURE 5. LMV1015-15 Gain vs. Frequency Over Temperature The LMV1015 is optimized to be used in audio band applications. By using the LMV1015, the gain response is flat within the audio band and has linearity and temperature stability Figure 5. NOISE 20128911 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 LMV1015-15 has a gain of 6 (15.6 dB) over the JFET, the output voltage of the microphone is 6.78 mVPP. By implementing the LMV1015-15, 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 www.national.com 8 LMV1015 Analog Series Application Section (Continued) 20128908 FIGURE 6. RF Noise Reduction 9 www.national.com LMV1015 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 with Large Dome Bump Technology NS Package Number XRA04ADA X1 = 0.975 mm X2 = 1.051 mm X3 = 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 X1 = 0.975 mm X2 = 1.051 mm X3 = 0.400 mm www.national.com 10 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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