OPA2343EA Datasheet, PDF (8/16 Pages) Texas Instruments – SINGLE-SUPPLY, RAIL-TO-RAIL OPERATIONAL AMPLIFIERS microAmplifier Series

APPLICATIONS INFORMATION
OPA343 series op amps are fabricated on a state-of-the-art
0.6 micron CMOS process. They are unity-gain stable and
suitable for a wide range of general-purpose applications.
Rail-to-rail input/output make them ideal for driving sam-
pling A/D converters. In addition, excellent ac performance
makes them well-suited for audio applications. The class AB
output stage is capable of driving 600Ω loads connected to
any point between V+ and ground.
Rail-to-rail input and output swing significantly increases
dynamic range, especially in low-supply applications. Fig-
ure 1 shows the input and output waveforms for the
OPA343 in unity-gain configuration. Operation is from a
single +5V supply with a 10kΩ load connected to V_S /2.
The input is a 5Vp-p sinusoid. Output voltage is approxi-
mately 4.98Vp-p.
Power-supply pins should be bypassed with 0.01µF ceramic
capacitors.
5
V_IN
V_S = +5, G = +1, R_L = 10kΩ
5
V_OUT
0
FIGURE 1. Rail-to-Rail Input and Output.
V+
Reference
Current
OPERATING VOLTAGE
OPA343 series op amps are fully specified from +2.7V to
+5V. However, supply voltage may range from +2.5V to
+5.5V. Parameters are guaranteed over the specified supply
range—a unique feature of the OPA343 series. In addition,
many specifications apply from –40°C to +85°C. Most
behavior remains virtually unchanged throughout the full
operating voltage range. Parameters which vary signifi-
cantly with operating voltages or temperature are shown in
the Typical Performance Curves.
RAIL-TO-RAIL INPUT
The input common-mode voltage range of the OPA343
series extends 500mV beyond the supply rails. This is
achieved with a complementary input stage—an N-channel
input differential pair in parallel with a P-channel differen-
tial pair, as shown in Figure 2. The N-channel pair is active
for input voltages close to the positive rail, typically (V+)
– 1.3V to 500mV above the positive supply. The P-channel
pair is on for inputs from 500mV below the negative supply
to approximately (V+) – 1.3V.
There is a small transition region, typically (V+) – 1.5V to
(V+) – 1.1V, in which both input pairs are on. This 400mV
transition region can vary ±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. 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 class AB output
stage. Normally, input bias current is approximately 200fA,
however, input voltages exceeding the power supplies by
V_IN+
V_IN–
V_BIAS1
Class AB
Control
V_O
Circuitry
V_BIAS2
V–
(Ground)
FIGURE 2. Simplified Schematic.
8
OPA343, 2343, 4343
SBOS090A