LMC6044AIM National Semiconductor, LMC6044AIM Datasheet - Page 11

• Manufacturer Part Number: LMC6044AIM
• Description: Operational Amplifier (Op-Amp) IC
• Manufacturer: National Semiconductor

Specifications of LMC6044AIM

• No. Of Amplifiers: 4
• Slew Rate: 0.02V/µs
• No. Of Pins: 8
• Mounting Type: Surface Mount
• Peak Reflow Compatible (260 C): No
• Leaded Process Compatible: No
• Package / Case: 8-NSOIC
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

Typical Single-Supply Applications
(Input pins are lifted out of PC board and soldered directly to components.
All other pins connected to PC board.)
The extremely high input impedance, and low power con-
sumption, of the LMC6044 make it ideal for applications that
require battery-powered instrumentation amplifiers. Ex-
amples of these type of applications are hand-held pH
probes, analytic medical instruments, magnetic field detec-
tors, gas detectors, and silicon based pressure transducers.
The circuit in Figure 7 is recommended for applications
where the common-mode input range is relatively low and
the differential gain will be in the range of 10 to 1000. This
two op-amp instrumentation amplifier features an indepen-
dent adjustment of the gain and common-mode rejection
trim, and a total quiescent supply current of less than 40 µA.
(V+ = 5.0 V
DC
)
FIGURE 6. Air Wiring
FIGURE 7. Two Op-Amp Instrumentation Amplifier
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To maintain ultra-high input impedance, it is advisable to use
ground rings and consider PC board layout an important part
of the overall system design (see Printed-Circuit-Board Lay-
out for High Impedance Work). Referring to Figure 7, the
input voltages are represented as a common-mode input
V
mode component of the input is accomplished by making the
ratio of R1/R2 equal to R3/R4. So that where,
A suggested design guideline is to minimize the difference of
value between R1 through R4. This will often result in im-
proved resistor tempco, amplifier gain, and CMRR over tem-
perature. If RN = R1 = R2 = R3 = R4 then the gain equation
can be simplified:
Due to the “zero-in, zero-out” performance of the LMC6044,
and output swing rail-rail, the dynamic range is only limited to
the input common-mode range of 0V to V
at room temperature. This feature of the LMC6044 makes it
an ideal choice for low-power instrumentation systems.
A complete instrumentation amplifier designed for a gain of
100 is shown in Figure 8. Provisions have been made for low
sensitivity trimming of CMRR and gain.
CM
plus a differential input V
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D
. Rejection of the common-
S
–2.3V, worst case
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