LMV751
LMV751 Low Noise, Low Vos, Single Op Amp
Literature Number: SNOS468D
LMV751
Low Noise, Low Vos, Single Op Amp
General Description
The LMV751 is a high performance CMOS operational am-
plifier intended for applications requiring low noise and low
input offset voltage. It offers modest bandwidth of 4.5MHz for
very low supply current and is unity gain stable.
The output stage is able to drive high capacitance, up to
1000pF and source or sink 8mA output current.
It is supplied in the space saving SOT23-5 Tiny package.
The LMV751 is designed to meet the demands of small size,
low power, and high performance required by cellular
phones and similar battery operated portable electronics.
Features
nLow noise 6.5nV/
nLow V
OS
(0.05mV typ.)
nWideband 4.5MHz GBP typ.
nLow supply current 500uA typ.
nLow supply voltage 2.7V to 5.0V
nGround-referenced inputs
nUnity gain stable
nSmall Package
Applications
nCellular phones
nPortable equipment
nRadio systems
Connection Diagram
SOT23-5
10108101
Top View
Ordering Information
Package Part Number Package Marking Transport Media NSC Drawing
5-Pin SOT23-5 LMV751M5 A32A 1k Units Tape and Reel MA05B
LMV751M5X 3k units Tape and Reel
Voltage Noise Gain/Phase
10108102 10108103
July 2002
LMV751 Low Noise, Low Vos, Single Op Amp
© 2002 National Semiconductor Corporation DS101081 www.national.com
Absolute Maximum Ratings (Note 1)
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.
ESD Tolerance (Note 3)
Human Body Model 2000V
Machine Model 200V
Differential Input Voltage ±Supply Voltage
Supply Voltage (V
+
-V
−
) 5.5V
Lead Temperature (Soldering, 10 sec.) 260˚C
Storage Temperature Range −65˚C to 150˚C
Junction Temperature (T
J
) (Note 4) 150˚C
Recommended Operating
Conditions
Supply Voltage 2.7V to 5.0V
Temperature Range −40˚C ≤T
J
≤85˚C
Thermal Resistance (θ
JA
) (Note 6)
M5 Package, SOT23-5 274˚C/W
2.7V Electrical Characteristics
V
+
= 2.7V, V
−
= 0V, V
CM
= 1.35V, T
A
= 25˚C unless otherwise stated. Boldface limits apply over the Temperature Range.
Symbol Parameter Condition Typ
(Note 5)
Limit
(Note 2) Units
V
OS
Input Offset Voltage 0.05 1.0
1.5
mV
max
V
CM
Input common-Mode Voltage
Range
For CMRR ≥50dB 0 V
min
1.4 1.3 V
max
CMRR Common Mode Rejection Ratio 0V <V
CM
<1.3V 100 85
70
dB
min
PSRR Power Supply Rejection Ratio V
+
= 2.7V to 5.0V 107 85
70
dB
min
I
S
Supply Current 0.5 0.8
0.85
mA
max
I
IN
Input Current 1.5 100 pA
max
I
OS
Input Offset Current 0.2 pA
A
VOL
Voltage Gain R
L
= 10k Connect to V
+
/2
V
O
= 0.2V to 2.2V
120 110
95 dB
min
R
L
= 2k Connect to V
+
/2
V
O
= 0.2V to 2.2V
120 100
85
V
O
Positive Voltage Swing R
L
= 10k Connect to V
+
/2 2.62 2.54
2.52 V
min
R
L
= 2k Connect to V
+
/2 2.62 2.54
2.52
V
O
Negative Voltage Swing R
L
= 10k Connect to V
+
/2 78 140
160 mV
max
R
L
= 2k Connect to V
+
/2 78 160
180
I
O
Output Current Sourcing, V
O
=0V
V
IN
(diff) = ±0.5V
12 6.0
1.5 mA
min
Sinking, V
O
= 2.7V
V
IN
(diff) = ±0.5V
11 6.0
1.5
e
n
(10Hz) Input Referred Voltage Noise 15.5 nV/
e
n
(1kHz) Input Referred Voltage Noise 7 nV/
LMV751
www.national.com 2
2.7V Electrical Characteristics (Continued)
V
+
= 2.7V, V
−
= 0V, V
CM
= 1.35V, T
A
= 25˚C unless otherwise stated. Boldface limits apply over the Temperature Range.
Symbol Parameter Condition Typ
(Note 5)
Limit
(Note 2) Units
e
n
(30kHz)
Input Referred Voltage Noise 7 10 nV/
max
I
N
(1kHz) Input Referred Current Noise 0.01 pA/
GBW Gain-Bandwidth Product 4.5 2 MHZ
min
SR Slew Rate 2 V/µs
5.0V Electrical Characteristics
V
+
= 5.0V, V
−
= 0V, V
CM
= 2.5V, T
A
= 25˚C unless otherwise stated.Boldface limits apply over the Temperature Range.
Symbol Parameter Typ
(Note 5)
Limit
(Note 2) Units
V
OS
Input Offset Voltage 0.05 1.0
1.5
mV
max
CMRR Common Mode Rejection Ratio 0V <V
CM
<3.6V 103 85
70
dB
min
V
CM
Input Common-Mode Voltage
Range
For CMRR ≥50dB 0 V
min
3.7 3.6 V
max
PSRR Power Supply Rejection Ratio V
+
= 2.7V to 5.0V 107 85
70
dB
min
I
S
Supply Current 0.6 0.9
0.95
mA
max
I
IN
Input Current 1.5 100 pA
max
I
OS
Input offset Current 0.2 pA
A
VOL
Voltage Gain R
L
= 10k Connect to V
+
/2
V
O
= 0.2V to 4.5V
120 110
95
db
min
R
L
= 2k Connect to V
+
/2
V
O
= 0.2V to 4.5V
120 100
85
V
O
Positive Voltage Swing R
L
= 10k Connect to V
+
/2 4.89 4.82
4.80 V
min
R
L
= 2k Connect to V
+
/2 4.89 4.82
4.80
V
O
Negative Voltage Swing R
L
= 10k Connect to V
+
/2 86 160
180 mV
max
R
L
= 2k Connect to V
+
/2 86 180
200
I
O
Output Current Sourcing, V
O
=0V
V
IN
(diff) = ±0.5V
15 8.0
2.5 mA
min
Sinking, V
O
=5V
V
IN
(diff) = ±0.5V
20 8.0
2.5
e
n
(10Hz) Input Referred Voltage Noise 15 nV/
e
n
(1kHz) Input Referred Voltage Noise 6.5 nV/
LMV751
www.national.com3
5.0V Electrical Characteristics (Continued)
V
+
= 5.0V, V
−
= 0V, V
CM
= 2.5V, T
A
= 25˚C unless otherwise stated.Boldface limits apply over the Temperature Range.
Symbol Parameter Typ
(Note 5)
Limit
(Note 2) Units
e
n
(30kHz)
Input Referred Voltage Noise 6.5 10 nV/
max
I
N
(1kHz) Input Referred Current Noise 0.01 pA/
GBW Gain-Bandwidth Product 5 2 MHz
min
SR Slew Rate 2.3 V/µs
Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Electrical specifications do not apply when operating the device
beyond its rated operating conditions.
Note 2: All limits are guaranteed by testing or statistical analysis
Note 3: Human body model, 1.5kΩin series with 100pF. Machine model, 200Ωin series with 1000pF.
Note 4: The maximum power dissipation is a function of TJ(MAX),θJA, and TA. The maximum allowable power dissipation at any ambient temperature is
PD=(T
J(MAX) -T
A)/θJA. All numbers apply for packages soldered directly into a PC board.
Note 5: Typical values represent the most likely parametric norm.
Note 6: All numbers are typical, and apply to packages soldered directly onto PC board in still air.
LMV751
www.national.com 4
Typical Performance Characteristics
Supply Current vs. Voltage V
OS
vs. V
CM
,V
+
= 2.7V
10108135 10108138
V
OS
vs. V
CM
,V
+
= 5.0V Source Current vs. Out, V
+
= 2.7V
10108137 10108128
Source Current vs. V
OUT
,V
+
= 5.0V Gain/Phase
10108129 10108103
LMV751
www.national.com5
Typical Performance Characteristics (Continued)
Sinking Current vs. V
OUT
,V
+
= 2.7V Sinking Current vs. V
OUT
,V
+
= 5.0V
10108130 10108131
V
OS
vs. V
+
V
IN
vs. V
OUT
,V
+
= 2.7V, R
L
=2k
10108136 10108132
V
IN
vs. V
OUT
,V
+
= 5.0V, R
L
= 2k Input Bias vs. V
CM
,T
A
= 25˚C
10108133 10108116
LMV751
www.national.com 6
Typical Performance Characteristics (Continued)
Input Bias vs. V
CM
,T
A
= 85˚C PSRR +
10108105 10108126
PSRR − Voltage Noise
10108125 10108102
CMRR
10108139
LMV751
www.national.com7
Application Hints
1.0 Noise
There are many sources of noise in a system: thermal noise,
shot noise, 1/f, popcorn noise, resistor noise, just to name a
few. In addition to starting with a low noise op amp, such as
the LMV751, careful attention to detail will result in the
lowest overall noise for the system.
1.1 To invert or not invert?
Both inverting and non-inverting amplifiers employ feedback
to stabilize the closed loop gain of the block being designed.
The loop gain (in decibels) equals the algebraic difference
between the open loop and closed loop gains. Feedback
improves the Total Harmonic Distortion (THD) and the output
impedance. The various noise sources, when input referred,
are amplified, not by the closed loop gain, but by the noise
gain. For a non-inverting amplifier, the noise gain is equal to
the closed loop gain, but for an inverting amplifier, the noise
gain is equal to the closed loop gain plus one. For large
gains, e.g., 100, the difference is negligible, but for small
gains, such as one, the noise gain for the inverting amplifier
would be two. This implies that non-inverting blocks are
preferred at low gains.
1.2 Source impedance
Because noise sources are uncorrelated, the system noise
is calculated by taking the RMS sum of the various noise
sources, that is, the square root of the sum of the squares. At
very low source impedances, the voltage noise will domi-
nate; at very high source impedances, the input noise cur-
rent times the equivalent external resistance will dominate.
For a detailed example calculation, refer to Note 1.
1.3 Bias current compensation resistor
In CMOS input op amps, the input bias currents are very low,
so there is no need to use R
COMP
(Figure 1 and 2) for bias
current compensation that would normally be used with early
generation bipolar op amps. In fact, inclusion of the resistor
would act as another thermal noise source in the system,
increasing the overall noise.
1.4 Resistor types
Thermal noise is generated by any passive resistive ele-
ment. This noise is ’white’; meaning it has a constant spec-
tral density. Thermal noise can be represented by a mean-
square voltage generator e
R2
in series with a noiseless
resistor, where e
R2
is given by: Where:
e
R2
= 4K TRB (volts)
2
Where T = temperature in ˚K
R = resistor value in ohms
B = noise bandwidth in Hz
K = Boltzmann’s constant (1.38 x 10-23 W-sec/˚K)
Actual resistor noise measurements may have more noise
than the calculated value. This additional noise component is
known as excess noise. Excess noise has a 1/f spectral
response, and is proportional to the voltage drop across the
resistor. It is convenient to define a noise index when refer-
ring to excess noise in resistors. The noise index is the RMS
value in uV of noise in the resistor per volt of DC drop across
the resistor in a decade of frequency. Noise index expressed
in dB is:
NI = 20 log ((E
EX
/V
DC
)x10
6
)db
Where: E
EX
= resistor excess noise in uV per frequency
decade.
V
DC
= DC voltage drop across the resistor.
Excess noise in carbon composition resistors corresponds to
a large noise index of +10 dB to -20 dB. Carbon film resistors
have a noise index of -10 dB to -25 dB. Metal film and wire
wound resistors show the least amount of excess noise, with
a noise index figure of -15 dB to -40 dB.
1.5 Other noise sources:
As the op amp and resistor noise sources are decreased,
other noise contributors will now be noticeable. Small air
currents across thermocouples will result in low frequency
variations. Any two dissimilar metals, such as the lead on the
IC and the solder and copper foil of the pc board, will form a
thermocouple. The source itself may also generate noise. An
example would be a resistive bridge. All resistive sources
generate thermal noise based on the same equation listed
above under ’resistor types’.(2)
1.6 Putting it all together
To a first approximation, the total input referred noise of an
op amp is:
E
t2
=e
n2
+e
req2
+(i
n
*Req)
2
where Req is the equivalent source resistance at the inputs.
At low impedances, voltage noise dominates. At high imped-
ances, current noise dominates. With a typical noise current
on most CMOS input op amps of 0.01 pA/ , the current
noise contribution will be smaller than the voltage noise for
Req less than one megohm.
2.0 Other Considerations
2.1 Comparator operation
Occasionally operational amplifiers are used as compara-
tors. This is not optimum for the LMV751 for several rea-
sons. First, the LMV751 is compensated for unity gain sta-
bility, so the speed will be less than could be obtained on the
same process with a circuit specifically designed for com-
parator operation. Second, op amp output stages are de-
signed to be linear, and will not necessarily meet the logic
levels required under all conditions. Lastly, the LMV751 has
the newer PNP-NPN common emitter output stage, charac-
teristic of many rail-to-rail output op amps. This means that
10108123
FIGURE 1.
10108124
FIGURE 2.
LMV751
www.national.com 8
Application Hints (Continued)
when used in open loop applications, such as comparators,
with very light loads, the output PNP will saturate, with the
output current being diverted into the previous stage. As a
result, the supply current will increase to the 20-30 mA.
range. When used as a comparator, a resistive load between
2kΩand 10kΩshould be used with a small amount of
hysteresis to alleviate this problem. When used as an op
amp, the closed loop gain will drive the inverting input to
within a few millivolts of the non-inverting input. This will
automatically reduce the output drive as the output settles to
the correct value; thus it is only when used as a comparator
that the current will increase to the tens of milliampere range.
2.2 Rail-to-Rail
Because of the output stage discussed above, the LMV751
will swing “rail-to-rail” on the output. This normally means
within a few hundred millivolts of each rail with a reasonable
load. Referring to the Electrical Characteristics table for 2.7V
to 5.0V, it can be seen that this is true for resistive loads of
2kΩand 10kΩ. The input stage consists of cascoded
P-channel MOSFETS, so the input common mode range
includes ground, but typically requires 1.2V to 1.3V head-
room from the positive rail. This is better than the industry
standard LM324 and LM358 that have PNP input stages,
and the LMV751 has the advantage of much lower input bias
currents.
2.3 Loading
The LMV751 is a low noise, high speed op amp with excel-
lent phase margin and stability. Capacitive loads up to 1000
pF can be handled, but larger capacitive loads should be
isolated from the output. The most straightforward way to do
this is to put a resistor in series with the output. This resistor
will also prevent excess power dissipation if the output is
accidentally shorted.
2.4 General Circuits
With the low noise and low input bias current, the LMV751
would be useful in active filters, integrators, current to volt-
age converters, low frequency sine wave generators, and
instrumentation amplifiers. (3)
Note: 1. Sherwin, Jim “Noise Specs Confusing?” AN-104, National Semicon-
ductor.
2. Christensen, John, “Noise-figure curve ease the selection of
low-noise op amps”, EDN, pp 81-84, Aug. 4, 1994
3. “Op Amp Circuit Collection”, AN-31, National Semiconductor.
LMV751
www.national.com9
Physical Dimensions inches (millimeters)
unless otherwise noted
SOT23-5
NS Package Number MA05B
LIFE SUPPORT POLICY
NATIONAL’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT
DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT AND GENERAL
COUNSEL OF NATIONAL SEMICONDUCTOR CORPORATION. As used herein:
1. Life support devices or systems are devices or
systems which, (a) are intended for surgical implant
into the body, or (b) support or sustain life, and
whose failure to perform when properly used in
accordance with instructions for use provided in the
labeling, can be reasonably expected to result in a
significant injury to the user.
2. A critical component is any component of a life
support device or system whose failure to perform
can be reasonably expected to cause the failure of
the life support device or system, or to affect its
safety or effectiveness.
National Semiconductor
Corporation
Americas
Email: support@nsc.com
National Semiconductor
Europe
Fax: +49 (0) 180-530 85 86
Email: europe.support@nsc.com
Deutsch Tel: +49 (0) 69 9508 6208
English Tel: +44 (0) 870 24 0 2171
Français Tel: +33 (0) 1 41 91 8790
National Semiconductor
Asia Pacific Customer
Response Group
Tel: 65-2544466
Fax: 65-2504466
Email: ap.support@nsc.com
National Semiconductor
Japan Ltd.
Tel: 81-3-5639-7560
Fax: 81-3-5639-7507
www.national.com
LMV751 Low Noise, Low Vos, Single Op Amp
National does not assume any responsibility for use of any circuitry described, no circuit patent licenses are implied and National reserves the right at any time without notice to change said circuitry and specifications.
IMPORTANT NOTICE
Texas Instruments Incorporated and its subsidiaries (TI) reserve the right to make corrections, modifications, enhancements, improvements,
and other changes to its products and services at any time and to discontinue any product or service without notice. Customers should
obtain the latest relevant information before placing orders and should verify that such information is current and complete. All products are
sold subject to TI’s terms and conditions of sale supplied at the time of order acknowledgment.
TI warrants performance of its hardware products to the specifications applicable at the time of sale in accordance with TI’s standard
warranty. Testing and other quality control techniques are used to the extent TI deems necessary to support this warranty. Except where
mandated by government requirements, testing of all parameters of each product is not necessarily performed.
TI assumes no liability for applications assistance or customer product design. Customers are responsible for their products and
applications using TI components. To minimize the risks associated with customer products and applications, customers should provide
adequate design and operating safeguards.
TI does not warrant or represent that any license, either express or implied, is granted under any TI patent right, copyright, mask work right,
or other TI intellectual property right relating to any combination, machine, or process in which TI products or services are used. Information
published by TI regarding third-party products or services does not constitute a license from TI to use such products or services or a
warranty or endorsement thereof. Use of such information may require a license from a third party under the patents or other intellectual
property of the third party, or a license from TI under the patents or other intellectual property of TI.
Reproduction of TI information in TI data books or data sheets is permissible only if reproduction is without alteration and is accompanied
by all associated warranties, conditions, limitations, and notices. Reproduction of this information with alteration is an unfair and deceptive
business practice. TI is not responsible or liable for such altered documentation. Information of third parties may be subject to additional
restrictions.
Resale of TI products or services with statements different from or beyond the parameters stated by TI for that product or service voids all
express and any implied warranties for the associated TI product or service and is an unfair and deceptive business practice. TI is not
responsible or liable for any such statements.
TI products are not authorized for use in safety-critical applications (such as life support) where a failure of the TI product would reasonably
be expected to cause severe personal injury or death, unless officers of the parties have executed an agreement specifically governing
such use. Buyers represent that they have all necessary expertise in the safety and regulatory ramifications of their applications, and
acknowledge and agree that they are solely responsible for all legal, regulatory and safety-related requirements concerning their products
and any use of TI products in such safety-critical applications, notwithstanding any applications-related information or support that may be
provided by TI. Further, Buyers must fully indemnify TI and its representatives against any damages arising out of the use of TI products in
such safety-critical applications.
TI products are neither designed nor intended for use in military/aerospace applications or environments unless the TI products are
specifically designated by TI as military-grade or "enhanced plastic."Only products designated by TI as military-grade meet military
specifications. Buyers acknowledge and agree that any such use of TI products which TI has not designated as military-grade is solely at
the Buyer's risk, and that they are solely responsible for compliance with all legal and regulatory requirements in connection with such use.
TI products are neither designed nor intended for use in automotive applications or environments unless the specific TI products are
designated by TI as compliant with ISO/TS 16949 requirements. Buyers acknowledge and agree that, if they use any non-designated
products in automotive applications, TI will not be responsible for any failure to meet such requirements.
Following are URLs where you can obtain information on other Texas Instruments products and application solutions:
Products Applications
Audio www.ti.com/audio Communications and Telecom www.ti.com/communications
Amplifiers amplifier.ti.com Computers and Peripherals www.ti.com/computers
Data Converters dataconverter.ti.com Consumer Electronics www.ti.com/consumer-apps
DLP®Products www.dlp.com Energy and Lighting www.ti.com/energy
DSP dsp.ti.com Industrial www.ti.com/industrial
Clocks and Timers www.ti.com/clocks Medical www.ti.com/medical
Interface interface.ti.com Security www.ti.com/security
Logic logic.ti.com Space, Avionics and Defense www.ti.com/space-avionics-defense
Power Mgmt power.ti.com Transportation and Automotive www.ti.com/automotive
Microcontrollers microcontroller.ti.com Video and Imaging www.ti.com/video
RFID www.ti-rfid.com
OMAP Mobile Processors www.ti.com/omap
Wireless Connectivity www.ti.com/wirelessconnectivity
TI E2E Community Home Page e2e.ti.com
Mailing Address: Texas Instruments, Post Office Box 655303, Dallas, Texas 75265
Copyright ©2011, Texas Instruments Incorporated
