lmc6462bimx National Semiconductor Corporation, lmc6462bimx Datasheet - Page 16

• Manufacturer Part Number: lmc6462bimx
• Description: Micropower, Rail-to-rail Input And Output Cmos Operational Amplifier
• Manufacturer: National Semiconductor Corporation

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Typical Single-Supply Applications
PRECISION CURRENT SOURCE
The output current I
OSCILLATORS
For single supply 5V operation, the output of the circuit will
swing from 0V to 5V. The voltage divider set up R
R
move from 1.67V (
behaves as the threshold voltage.
R
frequency of oscillation, f
where ∆t is the time the amplifier input takes to move from
1.67V to 3.33V. The calculations are shown below.
where τ = RC = 0.68 seconds
(Continued)
4
1
and C
will cause the non-inverting input of the LMC6462 to
FIGURE 21. 1 Hz Square-Wave Oscillator
FIGURE 20. Precision Current Source
1
determine the time constant of the circuit. The
1
⁄
3
OUT
of 5V) to 3.33V (
is given by:
OSC
is
2
⁄
3
of 5V). This voltage
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2
, R
3
and
16
→ t
and
→ t
Then,
= 1 Hz
LOW FREQUENCY NULL
Output offset voltage is the error introduced in the output
voltage due to the inherent input offset voltage V
amplifier.
Output Offset Voltage = (Input Offset Voltage) (Gain)
In the above configuration, the resistors R
mine the nominal voltage around which the input signal, V
should be symmetrical. The high frequency component of
the input signal V
quency component will be nulled since the DC level of the
output will be the input offset voltage of the LMC6462 plus
the bias voltage. This implies that the output offset voltage
due to the top amplifier will be eliminated.
1
2
= 0.27 seconds.
= 0.75 seconds
FIGURE 22. High Gain Amplifier
with Low Frequency Null
IN
will be unaffected while the low fre-
5
and R
OS
6
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, of an
deter-
IN