OPA373_16 Datasheet, PDF (9/37 Pages) Texas Instruments – CMOS Operational Amplifier

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APPLICATIONS
The OPA373 and OPA374 series op amps are unity-gain
stable and suitable for a wide range of general-purpose
applications. Rail-to-rail input and output make them ideal
for driving sampling Analog-to-Digital Converters (ADCs).
Excellent ac performance makes them well-suited for
audio applications. The class AB output stage is capable
of driving 100kΩ loads connected to any point between V+
and ground.
The input common-mode voltage range includes both
rails, allowing the OPA373 and OPA374 series op amps to
be used in virtually any single-supply application up to a
supply voltage of +5.5V.
Rail-to-rail input and output swing significantly increases
dynamic range, especially in low-supply applications.
Power-supply pins should be bypassed with 0.01µF
ceramic capacitors.
OPERATING VOLTAGE
The OPA373 and OPA374 op amps are specified and
tested over a power-supply range of +2.7V to +5.5V
(±1.35V to ±2.75V). However, the supply voltage may
range from +2.3V to +5.5V (±1.15V to ±2.75V). Supply
voltages higher than 7.0V (absolute maximum) can
permanently damage the amplifier. Parameters that vary
over supply voltage or temperature are shown in the
Typical Characteristics section of this data sheet.
COMMON-MODE VOLTAGE RANGE
The input common-mode voltage range of the OPA373
and OPA374 series extends 200mV beyond the supply
rails. This is achieved with a complementary input
stage—an N-channel input differential pair in parallel with
a P-channel differential pair. The N-channel pair is active
for input voltages close to the positive rail, typically
(V+) − 1.65V to 200mV above the positive supply, while
the P-channel pair is on for inputs from 200mV below the
negative supply to approximately (V+) − 1.65V. There is a
500mV transition region, typically (V+) − 1.9V to
(V+) − 1.4V, in which both pairs are on. This 500mV
transition region, shown in Figure 1, can vary ±300mV with
process variation. Thus, the transition region (both stages
on) can range from (V+) − 2.2V to (V+) − 1.7V on the low
end, up to (V+) − 1.6V to (V+) − 1.1V on the high end.
Within the 500mV transition region PSRR, CMRR, offset
voltage, offset drift, and THD may be degraded compared
to operation outside this region.
OPA373, OPA2373
OPA374
OPA2374, OPA4374
SBOS279E − SEPTEMBER 2003 − REVISED MAY 2008
2.0
1.5
1.0
0.5
0
−0.5
−1.0
−1.5
V−
V+
−2.0
−0.5 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0
Common−Mode Voltage (V)
Figure 1. Behavior of Typical Transition Region at
Room Temperature
RAIL-TO-RAIL INPUT
The input common-mode range extends from (V−) − 0.2V
to (V+) + 0.2V. For normal operation, inputs should be
limited to this range. The absolute maximum input voltage
is 500mV beyond the supplies. Inputs greater than the
input common-mode range but less than the maximum
input voltage, while not valid, will not cause any damage
to the op amp. Unlike some other op amps, if input current
is limited, the inputs may go beyond the supplies without
phase inversion, as shown in Figure 2.
V_IN
5V
V_OUT
G = +1V/V, V_S = 5V
0V
1µs/div
Figure 2. OPA373: No Phase Inversion with
Inputs Greater Than the Power-Supply Voltage
Normally, input bias current is approximately 500fA;
however, input voltages exceeding the power supplies by
more than 500mV can cause excessive current to flow in
or out of the input pins. Momentary voltages greater than
500mV beyond the power supply can be tolerated if the
current on the input pins is limited to 10mA. This is easily
accomplished with an input resistor; see Figure 3. (Many
input signals are inherently current-limited to less than
10mA, therefore, a limiting resistor is not required.)
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