OPA378_1 Datasheet, PDF (9/24 Pages) Texas Instruments – Low-Noise, 900kHz, RRIO, Precision OPERATIONAL AMPLIFIER Zerø-Drift Series

OPA378
OPA2378
www.ti.com ..................................................................................................................................................... SBOS417C – JANUARY 2008 – REVISED JUNE 2009
APPLICATIONS INFORMATION
The OPA378 and OPA2378 are unity-gain stable,
precision operational amplifiers that are free from
phase reversal. The use of proprietary Zerø-Drift
circuitry gives the benefit of low input offset voltage
over time and temperature as well as lowering the 1/f
noise component. This design provides the
optimization of gain, noise, and power, making the
OPA378 series one of the best performers in this
bandwidth range. As a result of the high PSRR, this
device works well in applications that run directly from
battery power without regulation. They are optimized
for low-voltage, single-supply operation. These
miniature, high-precision, low quiescent current
amplifiers offer high-impedance inputs that have a
common-mode range 100mV beyond the supplies,
excellent CMRR, and a rail-to-rail output that swings
within 10mV of the supplies. This design results in
superior performance for driving analog-to-digital
converters (ADCs) without degradation of differential
linearity.
OPERATING VOLTAGE
The OPA378 and OPA2378 can be used with single
or dual supplies from an operating range of V_S =
+2.2V (±1.1V) and up to V_S = +5.5V (±2.75V). This
device does not require symmetrical supplies, only a
differential supply voltage of 2.2V to 5.5V. A
power-supply rejection ratio of 1.5µV/V (typical)
ensures that the device functions with an unregulated
battery source. Supply voltages higher than +7V can
permanently damage the device; see the Absolute
Maximum Ratings table. Key parameters are assured
over the specified temperature range, T_A = –40°C to
+125°C. Parameters that vary over the supply voltage
or temperature range are shown in the Typical
Characteristics section of this data sheet.
50
40
V_S = ±2.75V
10 Typical Units Shown
30
20
10
0
-10
-20
-30
-40
-50
-3.0 -2.5 -2.0 -1.5 -1.0 -0.5 0 0.5 1.0 1.5 2.0 2.5 3.0
V_CM (V)
Figure 25. Offset Voltage versus Common-Mode
Voltage
Normally, input bias current is about 150pA; however,
input voltages exceeding the power supplies can
cause excessive current to flow into or out of the
input pins. Momentary voltages greater than the
power supply can be tolerated if the input current is
limited to 10mA. This limitation is easily accomplished
with an input resistor, as Figure 26 shows.
Current-limiting resistor
required if input voltage
exceeds supply rails by
³ 0.5V.
I_OVERLOAD
10mA max
V_IN
5kW
+5V
OPA378
V_OUT
INPUT VOLTAGE
The OPA378 and OPA2378 input common-mode
voltage range extends 0.05V beyond the supply rails.
The OPA378 achieves a common-mode rejection
ratio of 112dB (typical) over the common-mode
voltage range. Figure 25 shows the variation of offset
voltage over the entire specified common-mode
range for 10 typical units.
Figure 26. Input Current Protection
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Product Folder Link(s): OPA378 OPA2378