APPLICATIONS INFORMATION
OPA341 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 I/O 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 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. Figure 1 shows the input and output
waveforms for the OPA341 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 approximately 4.98Vp-p. Power-supply pins should
be bypassed with 0.01µF ceramic capacitors.
OPERATING VOLTAGE
OPA341 series op amps are fully specified from +2.7V to
+5.5V. However, supply voltage may range from +2.5V to
+5.5V. Parameters are tested over the specified supply
range—a unique feature of the OPA341 series. In addition,
many specifications apply from –55°C to +125°C. Most
behavior remains virtually unchanged throughout the full
operating voltage range. Parameters that vary significantly
with operating voltages or temperature are shown in the
Typical Characteristics.
RAIL-TO-RAIL INPUT
The input common-mode voltage range of the OPA341
series extends 300mV beyond the supply rails. This is achieved
with a complementary input stage—an N-channel input dif-
ferential pair in parallel with a P-channel differential 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
300mV above the positive supply. The P-channel pair is on
for inputs from 300mV below the negative supply to approxi-
mately (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.
V
S
= 5, G = +1, R
L
= 10kΩ
V
IN
2V/div
V
OUT
20µs/div
FIGURE 1. Rail-to-Rail Input and Output.
V+
Reference
Current
V
IN
+
V
IN
–
V
BIAS1
Class AB
Control
Circuitry
V
O
V
BIAS2
ENABLE (CMOS Input)
On = High
Off = Low
V–
(Ground)
FIGURE 2. Simplified Schematic.
OPA341, 2341
SBOS202A
9
BURR-BROWN [ BURR-BROWN CORPORATION ]
