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參數(shù)資料
| 型號(hào)： | LMV1012-07 |
| 廠商： | National Semiconductor Corporation |
| 英文描述： | Analog Pre-Amplified IC’s for High Gain Microphones |
| 中文描述： | 模擬預(yù)擴(kuò)增集成電路的高增益麥克風(fēng) |
| 文件頁數(shù)： | 10/15頁 |
| 文件大小： | 497K |
| 代理商： | LMV1012-07 |
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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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LMV1012-15 | 制造商:NSC 制造商全稱:National Semiconductor 功能描述:Pre-Amplified IC’s for High Gain 2-Wire Microphones |
| LMV1012-20 | 制造商:NSC 制造商全稱:National Semiconductor 功能描述:Pre-Amplified IC’s for High Gain 2-Wire Microphones |
| LMV1012-25 | 制造商:NSC 制造商全稱:National Semiconductor 功能描述:Pre-Amplified IC’s for High Gain 2-Wire Microphones |
| LMV1012TP-07 | 制造商:NSC 制造商全稱:National Semiconductor 功能描述:Pre-Amplified IC’s for High Gain 2-Wire Microphones |
| LMV1012TP-07/NOPB | 功能描述:音頻放大器 RoHS:否 制造商:STMicroelectronics 產(chǎn)品:General Purpose Audio Amplifiers 輸出類型:Digital 輸出功率: THD + 噪聲: 工作電源電壓:3.3 V 電源電流: 最大功率耗散: 最大工作溫度: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:TQFP-64 封裝:Reel |
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