1 Features
• Low offset voltage: ±125 μV
• Low offset voltage drift: ±0.3 μV/°C
• Low noise: 10.8 nV/√Hz at 1 kHz
• High common-mode rejection: 130 dB
• Low bias current: ±10 pA
• Rail-to-rail input and output
• Wide bandwidth: 4.5 MHz GBW
• High slew rate: 21 V/μs
• High capacitive load drive: 1 nF
• MUX-friendly/comparator inputs
– Amplifier operates with differential inputs up to
supply rail
– Amplifier can be used in open-loop or as
comparator
• Low quiescent current: 560 μA per amplifier
• Wide supply: ±1.35 V to ±20 V, 2.7 V to 40 V
• Robust EMIRR performance: EMI/RFI filters on
input and supply pins
• Differential and common-mode input voltage range
to supply rail

2 Applications
• Low-power audio preamplifier
• Multiplexed data-acquisition systems
• Test and measurement equipment
• ADC driver amplifiers
• SAR ADC reference buffers
• Programmable logic controllers
• High-side and low-side current sensing

3 Description
The OPAx991 family (OPA991, OPA2991, and
OPA4991) is a family of high voltage (40 V) general
purpose operational amplifiers. These devices offer
exceptional DC precision and AC performance,
including rail-to-rail input/output, low offset (±125 μV,
typical), low offset drift (±0.3 μV/°C, typical), low noise
(10.5 nV/√Hz and 1.8 μVPP), and 4.5-MHz bandwidth.
Unique features such as differential and commonmode
input-voltage range to the supply rail, high
output current (±75 mA), high slew rate (21 V/μs),
high capacitive load drive (1 nF), and shutdown
functionality make the OPAx991 a robust, highperformance
operational amplifier for high-voltage
industrial applications.
The OPAx991 family of op amps is available in microsize
packages (such as X2QFN and WSON), as well
as standard packages (such as SOT-23, SOIC, and
TSSOP), and is specified from
–40°C to 125°C.