LMP2015MF/NOPB National Semiconductor, LMP2015MF/NOPB Datasheet - Page 10

• Manufacturer Part Number: LMP2015MF/NOPB
• Description: IC OP AMP SGL R-R PREC SOT23-5
• Manufacturer: National Semiconductor
• Series: LMP®r

Specifications of LMP2015MF/NOPB

• Amplifier Type: General Purpose
• Number Of Circuits: 1
• Output Type: Rail-to-Rail
• Slew Rate: 4 V/µs
• Gain Bandwidth Product: 3MHz
• Current - Input Bias: 3pA
• Voltage - Input Offset: 0.12µV
• Current - Supply: 930µA
• Current - Output / Channel: 17mA
• Voltage - Supply, Single/dual (±): 2.7 V ~ 5.25 V
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: SOT-23-5, SC-74A, SOT-25
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• -3db Bandwidth: -
• Other names: LMP2015MF; LMP2015MF; LMP2015MFTR

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Application Information
THE BENEFITS OF THE LMP2015/LMP2016's
NO 1/f NOISE
Using patented methods, the LMP2015/LMP2016 eliminate
the 1/f noise present in other amplifiers. That noise, which
increases as frequency decreases, is a major source of mea-
surement error in all DC-coupled measurements. Low fre-
quency noise appears as a constantly changing signal in
series with any measurement being made. As a result, even
when the measurement is made rapidly, this constantly
changing noise signal will corrupt the result. The value of this
noise signal can be surprisingly large. For example: If a con-
ventional amplifier has a flat-band noise level of 10 nV/
and a noise corner of 10 Hz, the RMS noise at 0.001 Hz is 1
µV/
the frequency range 0.001 Hz to 1.0 Hz. In a circuit with a gain
of 1000, this produces a 0.50 mV peak-to-peak output error.
This number of 0.001 Hz might appear unreasonably low, but
when a data acquisition system is operating for 17 minutes, it
has been on long enough to include this error. In this same
time, the LMP2015/LMP2016 will have only a 0.21 mV output
error. This is smaller by 2.4 x. Keep in mind that this 1/f error
gets even larger at lower frequencies. At the extreme, many
people try to reduce this error by integrating or taking several
samples of the same signal. This is also doomed to failure
because the 1/f nature of this noise means that taking longer
samples just moves the measurement into lower frequencies
where the noise level is even higher.
The LMP2015/LMP2016 eliminate this source of error. The
noise level is constant with frequency so that reducing the
bandwidth reduces the errors caused by noise.
Another source of error that is rarely mentioned is the error
voltage caused by the inadvertent thermocouples created
when the common "Kovar type" IC package lead materials are
soldered to a copper printed circuit board. These steel based
leadframe materials can produce over 35 μV/°C when sol-
dered onto a copper trace. This can result in thermocouple
noise that is equal to the LMP2015/LMP2016 noise when
there is a temperature difference of only 0.0014°C between
the lead and the board!
For this reason, the lead frame of the LMP2015/LMP2016 is
made of copper. This results in equal and opposite junctions
which cancel this effect. The extremely small size of the
SOT23 package results in the leads being very close togeth-
er. This further reduces the probability of temperature differ-
ences and hence decreases thermal noise.
OVERLOAD RECOVERY
The LMP2015/LMP2016 recover from input overload much
faster than most chopper-stabilized op amps. Recovery from
driving the amplifier to 2X the full scale output, only requires
about 40 ms. Many chopper-stabilized amplifiers will take
from 250 ms to several seconds to recover from this same
overload. This is because large capacitors are used to store
the unadjusted offset voltage.
. This is equivalent to a 0.50 µV peak-to-peak error, in
10
The wide bandwidth of the LMP2015/LMP2016 enhance per-
formance when it is used as an amplifier to drive loads that
inject transients back into the output. ADCs (Analog-to-Digital
Converters) and multiplexers are examples of this type of
load. To simulate this type of load, a pulse generator produc-
ing a 1V peak square wave was connected to the output
through a 10 pF capacitor.
output to recover to 1% of the applied pulse is 80 ns. To re-
cover to 0.1% requires 860 ns. This rapid recovery is due to
the wide bandwidth of the output stage and large total GBWP.
NO EXTERNAL CAPACITORS REQUIRED
The LMP2015/LMP2016 do not need external capacitors.
This eliminates the problems caused by capacitor leakage
and dielectric absorption, which can cause delays of several
seconds from turn-on until the amplifier's error has settled.
MORE BENEFITS
The LMP2015/LMP2016 offer the benefits mentioned above
and more. These parts have rail-to-rail outputs and consume
only 950 µA of supply current while providing excellent DC
and AC electrical performance. In DC performance, the
LMP2015/LMP2016 achieve 130 dB of CMRR, 120 dB of
PSRR and 130 dB of open loop gain. In AC performance, the
LMP2015/LMP2016 provide 3 MHz of gain bandwidth product
and 4 V/µs of slew rate.
HOW THE LMP2015/LMP2016 WORK
The LMP2015/LMP2016 use new, patented techniques to
achieve the high DC accuracy traditionally associated with
chopper-stabilized amplifiers without the major drawbacks
produced by chopping. The LMP2015/LMP2016 continuously
monitor the input offset and correct this error. The conven-
tional chopping process produces many mixing products,
both sums and differences, between the chopping frequency
and the incoming signal frequency. This mixing causes a
large amount of distortion, particularly when the signal fre-
quency approaches the chopping frequency. Even without an
incoming signal, the chopper harmonics mix with each other
to produce even more trash. To explain this
a plot, of the output of a typical (MAX432) chopper-stabilized
op amp. This is the output when there is no incoming signal,
just the amplifier in a gain of −10 with the input grounded. The
chopper is operating at about 150 Hz; the rest is mixing prod-
ucts. Add an input signal and the noise gets much worse.
Compare this plot with
This data was taken under the exact same conditions. The
auto-zero action is visible at about 30 kHz but note the ab-
sence of mixing products at other frequencies. As a result, the
LMP2015/LMP2016 have very low distortion of 0.02% and
very low mixing products.
FIGURE 1. Overload Recovery Test
Figure 3
(Figure
of the LMP2015/LMP2016.
1) The typical time for the
Figure 2
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shows