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Copyright © 2016, Texas Instruments Incorporated

11

OPA4277-SP

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SBOS771 – DECEMBER 2016

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Copyright © 2016, Texas Instruments Incorporated

7 Detailed Description

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

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.

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.