OPA4277-SP Datasheet, PDF (11/21 Pages) Texas Instruments – High-Precision Operational Amplifier

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7 Detailed Description
OPA4277-SP
SBOS771 – DECEMBER 2016
7.1 Overview
The OPA4277-SP precision operational amplifier replaces the industry standard LM124-SP. It offers improved
noise, wider output voltage swing, and is twice as fast with half the quiescent current. Features include ultra-low
offset voltage and drift, low bias current, high common-mode rejection, and high power supply rejection.
7.2 Functional Block Diagram
V_supply+
V_in+
+
V_out
V_in±
±
V_supply±
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7.3 Feature Description
The OPA4277-SP operates from ±2- to ±18-V supplies with excellent performance. Unlike most operational
amplifiers which are specified at only one supply voltage, the OPA4277-SP precision operational amplifier is
specified for real-world applications; a single limit applies over the ±5- to ±15-V supply range. High performance
is maintained as the amplifier swings to the specified limits. Because the initial offset voltage (±50 μV max) is so
low, user adjustment is usually not required.
7.3.1 Input Protection
The inputs of the OPA4277-SP are protected with 1-kΩ series input resistors and diode clamps. The inputs can
withstand ±30-V differential inputs without damage. The protection diodes conduct current when the inputs are
overdriven. This may disturb the slewing behavior of unity-gain follower applications, but will not damage the
operational amplifier.
1k
+
1k
±
Figure 20. OPA4277-SP Input Protection
7.3.2 Input Bias Current Cancellation
The input stage base current of the OPA4277-SP is internally compensated with an equal and opposite
cancellation circuit. The resulting input bias current is the difference between the input stage base current and
the cancellation current. This residual input bias current can be positive or negative.
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