OPA340NA-250 Datasheet, PDF (10/28 Pages) Texas Instruments – SINGLE-SUPPLY, RAIL-TO-RAIL OPERATIONAL AMPLIFIERS MicroAmplifier™ Series

OPA340
OPA2340
OPA4340
SBOS073B – SEPTEMBER 1997 – REVISED NOVEMBER 2007
V+
Reference
Current
V_IN+
V_IN-
V_BIAS1
V_BIAS2
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Class AB
Control
V_O
Circuitry
V-
(Ground)
Figure 24. Simplified Schematic
I_OVERLOAD
10mA max
V_IN
5kW
V+
OPAx340
V_OUT
Figure 25. Input Current Protection for Voltages Exceeding the Supply Voltage
RAIL-TO-RAIL OUTPUT
A class AB output stage with common-source
transistors is used to achieve rail-to-rail output. For
light resistive loads (> 50kΩ), the output voltage is
typically a few millivolts from the supply rails. With
moderate resistive loads (2kΩ to 50kΩ), the output
can swing to within a few tens of millivolts from the
supply rails and maintain high open-loop gain. See
the typical characteristic curve Output Voltage Swing
vs Output Current.
CAPACITIVE LOAD AND STABILITY
OPA340 series op amps can drive a wide range of
capacitive loads. However, all op amps under certain
conditions may become unstable. Op amp
configuration, gain, and load value are just a few of
the factors to consider when determining stability. An
op amp in unity gain configuration is most susceptible
to the effects of capacitive load. The capacitive load
reacts with the op amp’s output resistance, along with
any additional load resistance, to create a pole in the
small-signal response which degrades the phase
margin. In unity gain, OPA340 series op amps
perform well, with a pure capacitive load up to
approximately 1000pF. Increasing gain enhances the
amplifier’s ability to drive more capacitance. See the
typical performance curve Small-Signal Overshoot vs
Capacitive Load.
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