1 Features
• Zero cross amplifier for 1.7V to 5.5V applications
• High rail-to-rail CMRR: 114dB typical
• High gain-bandwidth product: 20MHz
• Fast slew-rate: 33V/μs typical
• Fast 0.01% settling: 200ns typical for 2V step
• Low input offset voltage: ±150μV typical
• Low noise floor: 5.5nV/√Hz typical at 10kHz
• High output current: ±110mA typical ISC at 5.5V
• Quiescent current: 1.6mA/ch typical
• Rail-to-rail input and output
• Unity-gain stable
• Drives up to 150pF without sustained oscillations
• Internal RFI and EMI filtered input pins
• Operating temperature range: –40°C to 125°C

2 Applications
• Amplifier driver for ADCs
• High side current sensing
• Motor rotary encoders
• Transimpedance photodiode amplifiers
• Audio microphone pre-amplifiers
• Ultrasonic transducers

3 Description
The OPAx323 family of op amps includes single
(OPA323), dual (OPA2323), and quad-channel
(OPA4323), low-voltage (1.7V to 5.5V), highbandwidth
(20MHz) amplifiers (op amps) with a zerocrossover
input stage and a rail-to-rail output stage.
The zero-crossover input stage enables OPAx323
to achieve high linearity and low distortion for input
signals with rail-to-rail swing that are typical in
ADC driver applications. Gain-bandwidth of 20MHz
provides a fast settling response for ADC sampling
speeds between 0.5MSPS to 5MSPS depending
on the settling performance required. The OPAx323
is well-optimized for power savings as the device
consumes just 1.6mA typical quiescent current.
The OPAx323 easily supports precision performance
in high gain voltage sensing applications such as the
wheatsone bridge, as it features maximum offset drift
of 2μV/°C and thermal noise floor of 5.5nV/rt-Hz with
a minimum of 100dB CMRR. This unique combination
of higher precision (low offset, drift, noise, distortion,
and CMRR) and higher gain-bandwidth (fast settling
and slewing) enables use in multiple applications such
as the motor rotary encoders, microphone audio preamplifiers
and ultrasonic transducers.
The OPAx323 achieves a high slew-rate of 33V/μs
allowing for fast detection of faults in motor current
sensing applications. Unlike traditional amplifiers,
the zero-cross over input stage allows for identical
precision performance for both low and high-side
sensing applications, thus making OPAx323 the
best choice for current sensing in a variety of
end equipments such as the solar string inverters,
power delivery, grid and EV infrastructure. OPAx323S
devices provide shutdown functionality for additional
power savings and help disable the amplifier when
idle. The family features standard and small size as
well as leaded and QFN packages across all the
channel variants.