LMV721M7/NOPB National Semiconductor, LMV721M7/NOPB Datasheet - Page 11

• Manufacturer Part Number: LMV721M7/NOPB
• Description: IC OP AMP LOW VOLT LP SC-70-5
• Manufacturer: National Semiconductor
• Series: PowerWise®r

Specifications of LMV721M7/NOPB

• Amplifier Type: General Purpose
• Number Of Circuits: 1
• Output Type: Rail-to-Rail
• Slew Rate: 5.25 V/µs
• Gain Bandwidth Product: 10MHz
• Current - Input Bias: 260nA
• Voltage - Input Offset: 80µV
• Current - Supply: 1.03mA
• Current - Output / Channel: 52.6mA
• Voltage - Supply, Single/dual (±): 2.2 V ~ 5.5 V, ±1.1 V ~ 2.25 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: SC-70-5, SC-88A, SOT-323-5, SOT-353, 5-TSSOP
• Number Of Channels: 1
• Voltage Gain Db: 94 dB
• Common Mode Rejection Ratio (min): 70 dB
• Input Offset Voltage: 3 mV at 5 V
• Operating Supply Voltage: 3 V, 5 V
• Supply Current: 1.4 mA at 5 V
• Maximum Operating Temperature: + 85 C
• Minimum Operating Temperature: - 40 C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• -3db Bandwidth: -
• Lead Free Status / Rohs Status: Details
• Other names: LMV721M7; LMV721M7TR

The output can swing to both rails, maximizing the signal-to-
noise ratio in a low voltage system.
4.4 Active Filter
4.4.1 Simple Low-Pass Active Filter
The simple low-pass filter is shown in Figure 9. Its low-pass
frequency gain (ω
frequency gains other than unity to be obtained. The filter has
a −20dB/decade roll-off after its corner frequency fc. R
should be chosen equal to the parallel combination of R
R
sponse of the filter is shown in Figure 10.
3
to minimize error due to bias current. The frequency re-
FIGURE 8. Single-Supply Inverting Amplifier
FIGURE 9. Simple Low-Pass Active Filter
→
o) is defined by −R
3
/R
1
. This allows low-
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1
and
2
11
Note that the single-op-amp active filters are used in to the
applications that require low quality factor, Q(
quency (
product of gain times Q(
open loop voltage gain at the highest frequency of interest at
least 50 times larger than the gain of the filter at this frequen-
cy. In addition, the selected op amp should have a slew rate
that meets the following requirement:
Where ω
output peak-to-peak voltage.
FIGURE 11. A Battery Powered Microphone Preamplifier
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 pream-
plifier. The LMV721 is connected in an inverting configuration.
Resistors, R
tween V
for single supply use. The gain of the preamplifier, which is
50 (34dB), is set by resistors R
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
bias the electret microphone. Capacitors C
placed at the input and output of the op amp to block out the
DC voltage offset.
FIGURE 10. Frequency Response of Simple Low-pass
Slew Rate
CC
≤
H
5KHz), and low gain (
is the highest frequency of interest, and V
= 3V and ground. Thus, this configures the op amp
1
= R
≥
Active Filter in Figure 9
0.5 x (ω
2
= 4.7kΩ, sets the reference half way be-
≤
H
100). The op amp should have an
V
OPP
3
≤
= 10kΩ and R
) X 10
10), or a small value for the
−6
V/µsec
5
= 5kΩ is used to
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1
4
≤
= C
= 500kΩ. The
10), low fre-
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2
OPP
= 4.7µF
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is the