Datasheet
www.ti.com
APPLICATIONS INFORMATION
RAIL-TO-RAIL INPUT
V =+5,G=+1,R =10kW
S L
5
5
0
V
IN
V
OUT
2V/div
OPERATING VOLTAGE
OPA340
OPA2340
OPA4340
SBOS073B – SEPTEMBER 1997 – REVISED NOVEMBER 2007
from – 40 ° C to +85 ° C. Most behavior remains virtually
OPA340 series op amps are fabricated on a
unchanged throughout the full operating voltage
state-of-the-art, 0.6 micron CMOS process. They are
range. Parameters which vary significantly with
unity-gain stable and suitable for a wide range of
operating voltages or temperature are shown in the
general-purpose applications. Rail-to-rail input/output
Typical Characteristics .
make them ideal for driving sampling A/D converters.
In addition, excellent ac performance makes them
well-suited for audio applications. The class AB
output stage is capable of driving 600 Ω loads The input common-mode voltage range of the
connected to any point between V+ and ground. OPA340 series extends 500mV beyond the supply
rails. This is achieved with a complementary input
Rail-to-rail input and output swing significantly
stage — an N-channel input differential pair in parallel
increases dynamic range, especially in low-supply
with a P-channel differential pair (as shown in
applications. Figure 23 shows the input and output
Figure 24 ). The N-channel pair is active for input
waveforms for the OPA340 in unity-gain
voltages close to the positive rail, typically
configuration. Operation is from a single +5V supply
(V+) – 1.3V to 500mV above the positive supply,
with a 10k Ω load connected to V
S
/2. The input is a
while the P-channel pair is on for inputs from 500mV
5V
PP
sinusoid. Output voltage is approximately
below the negative supply to approximately
4.98V
PP
.
(V+) – 1.3V. There is a small transition region,
typically (V+) – 1.5V to (V+) – 1.1V, in which both
Power-supply pins should be bypassed with 0.01 µ F
pairs are on. This 400mV transition region can vary
ceramic capacitors.
± 300mV with process variation. Thus, the transition
region (both stages on) can range from (V+) – 1.8V to
(V+) – 1.4V on the low end, up to (V+) – 1.2V to (V+)
– 0.8V on the high end.
OPA340 series op amps are laser-trimmed to the
reduce offset voltage difference between the
N-channel and P-channel input stages, resulting in
improved common-mode rejection and a smooth
transition between the N-channel pair and the
P-channel pair. However, within the 400mV transition
region PSRR, CMRR, offset voltage, offset drift, and
THD may be degraded compared to operation
outside this region.
A double-folded cascode adds the signal from the two
input pairs and presents a differential signal to the
Figure 23. Rail-to-Rail Input and Output
class AB output stage. Normally, input bias current is
approximately 200fA; however, input voltages
exceeding the power supplies by more than 500mV
can cause excessive current to flow in or out of the
OPA340 series op amps are fully specified from
input pins. Momentary voltages greater than 500mV
+2.7V to +5V. However, supply voltage may range
beyond the power supply can be tolerated if the
from +2.5V to +5.5V. Parameters are ensured over
current on the input pins is limited to 10mA. This is
the specified supply range — a unique feature of the
easily accomplished with an input resistor, as shown
OPA340 series. In addition, many specifications apply
in Figure 25 . Many input signals are inherently
current-limited to less than 10mA; therefore, a limiting
resistor is not required.
Copyright © 1997 – 2007, Texas Instruments Incorporated Submit Documentation Feedback 9
Product Folder Link(s): OPA340 OPA2340 OPA4340