OPA1641 Datasheet, PDF (13/31 Pages) Texas Instruments – High-Performance, JFET-Input AUDIO OPERATIONAL AMPLIFIERS

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7 Detailed Description
OPA1641, OPA1642, OPA1644
SBOS484C – DECEMBER 2009 – REVISED DECEMBER 2015
7.1 Overview
The OPA164x family of operational amplifiers combine an ultra low noise JFET input stage with a rail-to-rail
output stage to provide high overall performance in audio applications. The internal topology was selected
specifically to deliver extremely low distortion while simultaneously consuming limited power and accommodating
small packages. These amplifiers are well-suited for analog signal processing applications such as active filter
circuits, pre-amplifiers, and tone controls. The unique input stage design and semiconductor processes used in
this part deliver extremely high performance even in applications with high source impedance and wide common-
mode voltage swings.
7.2 Functional Block Diagram
V+
Pre-Output Driver
IN-
IN+
OUT
V-
7.3 Feature Description
7.3.1 Phase Reversal Protection
The OPA164x family has internal phase-reversal protection. Many op amps exhibit 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 input of the OPA164x prevents phase reversal with excessive common-mode
voltage. Instead, the appropriate rail limits the output voltage. This performance is shown in Figure 29.
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