Datasheet

www.ti.com
V
BIAS1
V
BIAS2
V +
IN
V -
IN
ClassAB
Control
Circuitry
V
O
V-
(Ground)
V+
Reference
Current
5kW
OPAx340
10mAmax
V+
V
IN
V
OUT
I
OVERLOAD
RAIL-TO-RAIL OUTPUT CAPACITIVE LOAD AND STABILITY
OPA340
OPA2340
OPA4340
SBOS073B – SEPTEMBER 1997 – REVISED NOVEMBER 2007
Figure 24. Simplified Schematic
Figure 25. Input Current Protection for Voltages Exceeding the Supply Voltage
A class AB output stage with common-source OPA340 series op amps can drive a wide range of
transistors is used to achieve rail-to-rail output. For capacitive loads. However, all op amps under certain
light resistive loads (> 50k Ω ), the output voltage is conditions may become unstable. Op amp
typically a few millivolts from the supply rails. With configuration, gain, and load value are just a few of
moderate resistive loads (2k Ω to 50k Ω ), the output the factors to consider when determining stability. An
can swing to within a few tens of millivolts from the op amp in unity gain configuration is most susceptible
supply rails and maintain high open-loop gain. See to the effects of capacitive load. The capacitive load
the typical characteristic curve Output Voltage Swing reacts with the op amp ’ s output resistance, along with
vs Output Current. 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.
10 Submit Documentation Feedback Copyright © 1997 – 2007, Texas Instruments Incorporated
Product Folder Link(s): OPA340 OPA2340 OPA4340