LMV831MGEVAL National Semiconductor, LMV831MGEVAL Datasheet - Page 13
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LMV831MGEVAL
Manufacturer Part Number
LMV831MGEVAL
Description
BOARD EVAL FOR LMV831 3.3MHZ OA
Manufacturer
National Semiconductor
Series
PowerWise®r
Specifications of LMV831MGEVAL
Channels Per Ic
1 - Single
Amplifier Type
General Purpose
Output Type
Single-Ended
Slew Rate
2 V/µs
Current - Output / Channel
66mA
Operating Temperature
-40°C ~ 125°C
Current - Supply (main Ic)
250µA
Voltage - Supply, Single/dual (±)
2.7 V ~ 5.5 V
Board Type
Fully Populated
Utilized Ic / Part
LMV831
Lead Free Status / RoHS Status
Lead free / RoHS Compliant
-3db Bandwidth
-
Application Information
INTRODUCTION
The LMV831, LMV832 and LMV834 are operational ampli-
fiers with excellent specifications, such as low offset, low
noise and a rail-to-rail output. These specifications make the
LMV831, LMV832 and LMV834 great choices for medical and
instrumentation applications such as diagnosis equipment.
The low supply current is perfectly suited for battery powered
equipment. The small packages, SC-70 package for the
LMV831, the MSOP package for the dual LMV832 and the
TSSOP package for the quad LMV834, make these parts a
perfect choice for portable electronics. Additionally, the EMI
hardening makes the LMV831, LMV832 or LMV834 a must
for almost all op amp applications. Most applications are ex-
posed to Radio Frequency (RF) signals such as the signals
transmitted by mobile phones or wireless computer peripher-
als. The LMV831, LMV832 and LMV834 will effectively re-
duce disturbances caused by RF signals to a level that will be
hardly noticeable. This again reduces the need for additional
filtering and shielding. Using this EMI resistant series of op
amps will thus reduce the number of components and space
needed for applications that are affected by EMI, and will help
applications, not yet identified as possible EMI sensitive, to
be more robust for EMI.
INPUT CHARACTERISTICS
The input common mode voltage range of the LMV831,
LMV832 and LMV834 includes ground, and can even sense
well below ground. The CMRR level does not degrade for in-
put levels up to 1.2V below the supply voltage. For a supply
voltage of 5V, the maximum voltage that should be applied to
the input for best CMRR performance is thus 3.8V.
When not configured as unity gain, this input limitation will
usually not degrade the effective signal range. The output is
rail-to-rail and therefore will introduce no limitations to the
signal range.
The typical offset is only 0.25 mV, and the TCV
0.5 μV/°C, specifications close to precision op amps.
CMRR MEASUREMENT
The CMRR measurement results may need some clarifica-
tion. This is because different setups are used to measure the
AC CMRR and the DC CMRR.
The DC CMRR is derived from ΔV
is stated in the tables, and is tested during production testing.
The AC CMRR is measured with the test circuit shown in
Figure 1.
OS
versus ΔV
CM
. This value
OS
is
13
The configuration is largely the usually applied balanced con-
figuration. With potentiometer P1, the balance can be tuned
to compensate for the DC offset in the DUT. The main differ-
ence is the addition of the buffer. This buffer prevents the
open-loop output impedance of the DUT from affecting the
balance of the feedback network. Now the closed-loop output
impedance of the buffer is a part of the balance. As the closed-
loop output impedance is much lower, and by careful selec-
tion of the buffer also has a larger bandwidth, the total effect
is that the CMRR of the DUT can be measured much more
accurately. The differences are apparent in the larger mea-
sured bandwidth of the AC CMRR.
One artifact from this test circuit is that the low frequency
CMRR results appear higher than expected. This is because
in the AC CMRR test circuit the potentiometer is used to com-
pensate for the DC mismatches. So, mainly AC mismatch is
all that remains. Therefore, the obtained DC CMRR from this
AC CMRR test circuit tends to be higher than the actual DC
CMRR based on DC measurements.
The CMRR curve in Figure 2 shows a combination of the AC
CMRR and the DC CMRR.
FIGURE 1. AC CMRR Measurement Setup
FIGURE 2. CMRR Curve
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