OPA4131NAG4 Datasheet, PDF (7/20 Pages) Texas Instruments – General-Purpose FET-INPUT OPERATIONAL AMPLIFIERS

APPLICATIONS INFORMATION
The OPA131 series op amps are unity-gain stable and
suitable for a wide range of general-purpose applications.
Power-supply pins should be bypassed with 10nF ceramic
capacitors or larger.
The OPA131 series op amps are free from unexpected
output phase-reversal common with FET op amps. Many
FET-input op amps exhibit phase-reversal of the output when
the input common-mode voltage range is exceeded. This can
occur in voltage-follower circuits, causing serious problems
in control-loop applications. All circuitry is completely inde-
pendent in dual and quad versions, assuring normal behavior
when one amplifier in a package is overdriven or short-
circuited.
OFFSET VOLTAGE TRIM
The OPA131 (single op amp version) provides offset volt-
age trim connections on pins 1 and 5. Offset voltage can be
adjusted by connecting a potentiometer as shown in Figure
1. This adjustment should be used only to null the offset of
the op amp, not system offset or offset produced by the
signal source.
V+
OPA131
2 ^{7 (Single op amp only)}
6
3
OPA131
5
1
4 _100kΩ
Trim Range: ±20mV typ
V–
FIGURE 1. OPA131 Offset Voltage Trim Circuit.
INPUT BIAS CURRENT
The input bias current is approximately 5pA at room tem-
perature and increases with temperature as shown in the
typical characteristic “Input Bias Current vs Temperature.”
Input bias current also varies with common-mode voltage
and power supply voltage. This variation is dependent on the
voltage between the negative power supply and the com-
mon-mode input voltage. The effect is shown in the typical
curve “Input Bias Current vs Common-Mode Voltage.”
OPA131, 2131, 4131
7
SBOS040A
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