Datasheet

LMV721-N, LMV722-N
SNOS414I –AUGUST 1999–REVISED AUGUST 2013 www.ti.com
Here is a LMV721-N used as a microphone preamplifier. Since the LMV721-N is a low noise and low power op
amp, it makes it an ideal candidate as a battery powered microphone preamplifier. The LMV721-N is connected
in an inverting configuration. Resistors, R
1
= R
2
= 4.7kΩ, sets the reference half way between V
CC
= 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 R
4
= 500kΩ. The gain bandwidth product for the LMV721-N 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 C
1
= C
2
= 4.7µF placed at the input and output of the op amp to
block out the DC voltage offset.
Connection Diagrams
Top View Top View
Figure 34. 5-Pin SC70 and SOT-23 Packages Figure 35. 8-Pin SOIC and VSSOP Packages
See Package Numbers DCK0005A AND DBV0005A See Package Numbers D0008A and DGK0008A
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Product Folder Links: LMV721-N LMV722-N