OPA211ID datasheet(21/45 Pages) TI1

21 / 45 page

OPA211

Output

Input

OPA211, OPA2211

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SBOS377H – OCTOBER 2006 – REVISED NOVEMBER 2015

9 Application and Implementation

NOTE

Information in the following applications sections is not part of the TI component

specification, and TI does not warrant its accuracy or completeness. TI’s customers are

responsible for determining suitability of components for their purposes. Customers should

validate and test their design implementation to confirm system functionality.

9.1 Application Information

The OPA211 and OPA2211 are unity-gain stable, precision operational amplifiers with very-low noise.

Applications with noisy or high-impedance power supplies require decoupling capacitors close to the device pins.

In most cases, 0.1-

μF capacitors are adequate.

9.1.1 Operating Voltage

OPA211 series operational amplifiers operate from ±2.25- to ±18-V supplies while maintaining excellent

performance. The OPA211 series can operate with as little as 4.5 V between the supplies and with up to 36 V

between the supplies. However, some applications do not require equal positive and negative output voltage

swing. With the OPA211 series, power-supply voltages do not need to be equal. For example, the positive supply

could be set to 25 V with the negative supply at –5 V or vice-versa.

The common-mode voltage must be maintained within the specified range. In addition, key parameters are

assured over the specified temperature range, TA = –40°C to +125°C. Parameters that vary significantly with

operating voltage or temperature are shown in the Typical Characteristics.

9.1.2 Input Protection

The input terminals of the OPA211 are protected from excessive differential voltage with back-to-back diodes, as

shown in Figure 44. In most circuit applications, the input protection circuitry has no consequence. However, in

low-gain or G = 1 circuits, fast ramping input signals can forward bias these diodes because the output of the

amplifier cannot respond rapidly enough to the input ramp. This effect is shown in Figure 30 of the Typical

Characteristics. If the input signal is fast enough to create this forward bias condition, the input signal current

must be limited to 10 mA or less. If the input signal current is not inherently limited, an input series resistor can

be used to limit the signal input current. This input series resistor degrades the low-noise performance of the

OPA211, and is discussed in the Noise Performance section of this data sheet. Figure 44 shows an example

implementing a current-limiting feedback resistor.

Figure 44. Pulsed Operation

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OPA211ID Datasheet(PDF) 21 Page - Texas Instruments