LMV721 datasheet(11/15 Pages) NSC

部品番号	LMV721

部品情報	10MHz, Low Noise, Low Voltage, and Low Power Operational Amplifier

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メーカー	NSC [National Semiconductor (TI)]

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Application Notes (Continued)

Here is a LMV721 used as a microphone preamplifier. Since the LMV721 is a low noise and low power op amp, it makes it an

ideal candidate as a battery powered microphone preamplifier. The LMV721 is connected in an inverting configuration. Resistors,

1 = R2 = 4.7kΩ, sets the reference half way between VCC = 3V and ground. Thus, this configures the op amp for single supply

use. The gain of the preamplifier, which is 50 (34dB), is set by resistors R

3 = 10kΩ and R4 = 500kΩ. The gain bandwidth product

for the LMV721 is 10 MHz. This is sufficient for most audio application since the audio range is typically from 20 Hz to 20kHz. A

resistor R

5 = 5kΩ is used to bias the electret microphone. Capacitors C1 = C2 = 4.7µF placed at the input and output of the op

amp to block out the DC voltage offset.

DS100922-44

FIGURE 11. A Battery Powered Microphone Preamplifier

LMV721 データシート(PDF) 11 Page - National Semiconductor (TI)