LMC7111 Datasheet, PDF (13/18 Pages) National Semiconductor (TI) – Tiny CMOS Operational Amplifier with Rail-to-Rail Input

Application Information (Continued)
C_F and R_isolation prevent oscillations when driving capacitive loads.
FIGURE 4. Stable Negative Bias
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7.0 Reference Buffer for A-to-D Converters
The LMC7111 can be used as a voltage reference buffer for
analog-to-digital converters. This works best for A-to-D con-
verters whose reference input is a static load, such as dual
slope integrating A-to-Ds. Converters whose reference input
is a dynamic load (the reference current changes with time)
may need a faster device, such as the LMC7101 or the
LMC7131.
The small size of the LMC7111 allows it to be placed close to
the reference input. The low supply current (25 µA typical)
saves power.
For A-to-D reference inputs which require higher accuracy
and lower offset voltage, please see the LMC6462
datasheet. The LMC6462 has performance similar to the
LMC7111. The LMC6462 is available in two grades with re-
duced input voltage offset.
8.0 Dual and Quad Devices with Similar Performance
The LMC6462 and LMC6464 are dual and quad devices with
performance similar to the LMC7111. They are available in
both conventional through-hole and surface mount packag-
ing. Please see the LMC6462/4 datasheet for details.
9.0 SPICE Macromodel
A SPICE macromodel is available for the LMC7111. This
model includes simulation of:
• Input common-mode voltage range
• Frequency and transient response
• Quiescent and dynamic supply current
• Output swing dependence on loading conditions and
many more characteristics as listed on the macro model
disk. Contact your local National Semiconductor sales of-
fice to obtain an operational amplifier spice model library
disk.
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10.0 Additional SOT23-5 Tiny
Devices
National Semiconductor has additional parts available in the
space saving SOT23 Tiny package, including amplifiers,
voltage references, and voltage regulators. These devices
include —
LMC7101 1 MHz gain-bandwidth rail-to-rail input and out-
put amplifier — high input impedance and high
gain, 700 µA typical current 2.7V, 3V, 5V and 15V
specifications.
LM7131 Tiny Video amp with 70 MHz gain bandwidth.
Specified at 3V, 5V and ± 5V supplies.
LMC7211 Comparator in a tiny package with rail-to-rail in-
put and push-pull output. Typical supply current
of 7 µA. Typical propagation delay of 7 µs. Speci-
fied at 2.7V, 5V and 15V supplies.
LMC7221 Comparator with an open drain output for use in
mixed voltage systems. Similar to the LMC7211,
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