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参数资料
| 型号： | LMV1012UP-20 |
| 厂商： | NATIONAL SEMICONDUCTOR CORP |
| 元件分类： | 音频／视频放大 |
| 英文描述： | Pre-Amplified IC’s for High Gain 2-Wire Microphones |
| 中文描述： | 1 CHANNEL, AUDIO PREAMPLIFIER, PBGA4 |
| 封装： | 0.40 MM HEIGHT, LEAD FREE, MO-211CA, MICRO, SMD-4 |
| 文件页数： | 10/15页 |
| 文件大小： | 497K |
| 代理商： | LMV1012UP-20 |
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 V
through a resistor. This
phantom biasing allows both supply voltage and output sig-
nal on one connection.
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.
This filter 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 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.
The signal to noise ratio (SNR) is measured with a 1 kHz
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 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 hear-
ing of the human ear. The sound pressure level (SPL) in
decibels is defined by:
Sound pressure level (dB) = 20 log P
m
/P
O
Where,
P
m
is the measured sound pressure
P
O
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
20058702
FIGURE 1. Built in Gain
20058709
FIGURE 2. A-Weighted Filter
20058710
FIGURE 3. Noise Measurement Setup
L
www.national.com
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相关PDF资料 |
PDF描述 |
|---|---|
| LMV1012UP-25 | Reed Relay; Contacts:SPST; Contact Carry Current:1.5A; Coil Voltage DC Max:12V; Relay Terminals:Thru Hole; Switching Current Max:0.5A; Switching Voltage Max:200V; Contact Carrying Power:10W; Leaded Process Compatible:Yes RoHS Compliant: Yes |
| LMV1012UPX-07 | Pre-Amplified IC’s for High Gain 2-Wire Microphones |
| LMV1012UPX-15 | Pre-Amplified IC’s for High Gain 2-Wire Microphones |
| LMV1012UPX-20 | Pre-Amplified IC’s for High Gain 2-Wire Microphones |
| LMV1012UPX-25 | Pre-Amplified IC’s for High Gain 2-Wire Microphones |
相关代理商/技术参数 |
参数描述 |
|---|---|
| LMV1012UP-20/NOPB | 功能描述:音频放大器 RoHS:否 制造商:STMicroelectronics 产品:General Purpose Audio Amplifiers 输出类型:Digital 输出功率: THD + 噪声: 工作电源电压:3.3 V 电源电流: 最大功率耗散: 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:TQFP-64 封装:Reel |
| LMV1012UP-25 | 制造商:Texas Instruments 功能描述:AMP, MICROPHONE, 25DB GAIN, SMD, 1013 制造商:Texas Instruments 功能描述:AMP, MICROPHONE, 25DB GAIN, SMD, 1013; No. of Channels:1; Supply Voltage Range:2V to 5V; Amplifier Case Style:BGA; No. of Pins:4; Load Impedance:2.2kohm; Operating Temperature Min:-40C; Operating Temperature Max:85C; SVHC:No SVHC ;RoHS Compliant: Yes |
| LMV1012UP-25/NOPB | 功能描述:音频放大器 RoHS:否 制造商:STMicroelectronics 产品:General Purpose Audio Amplifiers 输出类型:Digital 输出功率: THD + 噪声: 工作电源电压:3.3 V 电源电流: 最大功率耗散: 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:TQFP-64 封装:Reel |
| LMV1012UPX-07 | 制造商:NSC 制造商全称:National Semiconductor 功能描述:Pre-Amplified IC’s for High Gain 2-Wire Microphones |
| LMV1012UPX-07/NOPB | 功能描述:音频放大器 RoHS:否 制造商:STMicroelectronics 产品:General Purpose Audio Amplifiers 输出类型:Digital 输出功率: THD + 噪声: 工作电源电压:3.3 V 电源电流: 最大功率耗散: 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:TQFP-64 封装:Reel |
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