7 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, as well as validating and testing their design

implementation to confirm system functionality.

7.1 Application Information

The OPAx132 series operational amplifiers are unity-gain stable and an excellent choice for a wide range of

general-purpose applications. Bypass power-supply pins with 10nF ceramic capacitors or larger.

The OPAx132 series operational amplifiers are free from unexpected output phase reversal common with FET

operational amplifiers. Many FET-input operational amplifiers exhibit phase-reversal of the output when the input

common-mode voltage range is exceeded. This phase reversal can occur in voltage-follower circuits, causing

serious problems in control-loop applications. The OPAx132 series of operational amplifiers are free from this

undesirable behavior. All circuitry is completely independent in dual and quad versions, maintaining normal

behavior when one amplifier in a package is overdriven or short-circuited.

7.1.1 Operating Voltage

The OPAx132 series of operation amplifiers operate with power supplies from ±2.5V to ±18V with excellent

performance. Although specifications are production tested with ±15V supplies, most behavior remains

unchanged throughout the full operating voltage range. Parameters which vary significantly with operating

voltage are shown in Section 5.8 .

7.1.2 Offset Voltage Trim

The offset voltage of the OPAx132 amplifiers is laser trimmed and usually requires no user adjustment. The

OPAx132 provide less than ±500µV of input offset voltage and less than 10µV/°C of input offset voltage drift over

the operating temperature range

7.1.3 Input Bias Current

The FET-inputs of the OPAx132 series provide very low input bias current and cause negligible errors in most

applications. For applications where low input bias current is crucial, minimize junction temperature rise. The

input bias current of FET-input operational amplifiers increases with temperature; see also Figure 5-5.

The OPAx132 series can be operated at reduced power supply voltage to minimize power dissipation and

temperature rise. Using ±3V supplies reduces power dissipation to one-fifth used at ±15V.

The dual and quad versions have higher total power dissipation than the single version, leading to higher

junction temperature. Thus, a warmed-up quad has higher input bias current than a warmed-up single.

Furthermore, an SOIC generally has higher junction temperature than a DIP at the same ambient temperature

because of a larger θJA.

Printed-circuit-board (PCB) layout also helps minimize junction temperature rise. Minimize temperature rise by

soldering the devices to the PCB rather than using a socket. Wide copper traces also help dissipate the heat by

acting as an additional heat sink.

Input stage cascode circuitry keeps the input bias current virtually unchanged throughout the full input common-

mode range of the OPAx132 series. See also Figure 5-6.

OPA132, OPA2132, OPA4132

SBOS054C – JANUARY 1995 – REVISED AUGUST 2024

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