OPAX189 datasheet(21/52 Pages) TI

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8.3 Feature Description

The OPAx189 series of op amps can be used with single or dual supplies from an operating range of VS = 4.5

V (±2.25 V) up to VS = 36 V (±18 V). These devices do not require symmetrical supplies; they only require a

minimum supply voltage of 4.5 V (±2.25 V). For VS less than ±2.5 V, the

common-mode input range does not include midsupply. Supply voltages higher than 40 V can permanently

damage the device; see the Absolute Maximum Ratings table for details. Key parameters are given over the

specified temperature range, TA = –40°C to +125°C, in the Electrical Characteristics table. Key parameters that

vary over the supply voltage, temperature range, or frequency are shown in the Typical Characteristics section.

The OPAx189 is unity-gain stable and free from unexpected output phase reversal. This device uses a

proprietary, periodic autocalibration technique to provide low input offset voltage and very low input offset

voltage drift over time and temperature. For lowest offset voltage and precision performance, optimize circuit

layout and mechanical conditions. Avoid temperature gradients that create thermoelectric (Seebeck) effects in

the thermocouple junctions formed from connecting dissimilar conductors. Cancel these thermally-generated

potentials by ensuring they are equal on both input pins. Other layout and design considerations include:

• Use low thermoelectric-coefficient conditions (avoid dissimilar metals).

• Thermally isolate components from power supplies or other heat sources.

• Shield operational amplifier and input circuitry from air currents, such as cooling fans.

Follow these guidelines to reduce the likelihood of junctions being at different temperatures, which may cause

thermoelectric voltages of 0.1 µV/°C or higher, depending on the materials used. See the Layout Guidelines

section for details and a layout example.

8.3.1 Operating Characteristics

The OPAx189 is specified for operation from 4.5 V to 36 V (±2.25 V to ±18 V). Many specifications apply from –

40°C to +125°C. Parameters that can exhibit significant variance with regard to operating voltage or temperature

are presented in the Typical Characteristics section.

8.3.2 Phase-Reversal Protection

The OPAx189 has an internal phase-reversal protection. Many op amps exhibit a phase reversal when the

input is driven beyond the linear common-mode range. This condition is most often encountered in noninverting

circuits when the input is driven beyond the specified common-mode voltage range, causing the output to

reverse into the opposite rail. The OPAx189 input prevents phase reversal with excessive common-mode

voltage. Instead, the output limits into the appropriate rail. This performance is shown in Figure 8-1.

Time (1 ms/div)

Vout (V)

Vin (V)

C017

Figure 8-1. No Phase Reversal

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OPA189, OPA2189, OPA4189

SBOS830I – SEPTEMBER 2017 – REVISED OCTOBER 2021

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