38V, Low-Noise, MOS-Input, Low-Power Op Amp

Great Combination of Low Power and Low Noise in a Small Package

Please check latest availability status for a specific part variant.


The MAX9945 operational amplifier features an excellent combination of low operating power and low input voltage noise. In addition, MOS inputs enable the MAX9945 to feature low input bias currents and low input current noise. The device accepts a wide supply voltage range from 4.75V to 38V and draws a low 400µA quiescent current. The MAX9945 is unity-gain stable and is capable of rail-to-rail output voltage swing.

The MAX9945 is ideal for portable medical and industrial applications that require low noise analog front-ends for performance applications such as photodiode transimpedance and chemical sensor interface circuits.

The MAX9945 is available in both an 8-pin µMAX® and a space-saving, 6-pin TDFN package, and is specified over the automotive operating temperature range (-40°C to +125°C).
MAX9945: Typical Operating Circuit MAX9945: Typical Operating Circuit Enlarge+

Key Features

  • +4.75V to +38V Single-Supply Voltage Range
  • ±2.4V to ±19V Dual-Supply Voltage Range
  • Rail-to-Rail Output Voltage Swing
  • 400µA Low Quiescent Current
  • 50fA Low Input Bias Current
  • 1fA/ Low Input Current Noise
  • 15nV/ Low Noise
  • 3MHz Unity-Gain Bandwidth
  • Wide Temperature Range from -40°C to +125°C
  • Available in Space-Saving, 6-Pin TDFN Package (3mm x 3mm)


  • Active Filters and Signal Processing
  • Automatic Test Equipment (ATE)
  • Chemical Sensor Interface
  • Displays: Industrial, Front Panel, and Instrumentation
  • High-Performance Audio Line Out
  • Industrial Sensors and Instrumentation
  • Industrial: Process Measurement and Control
  • Medical Pulse Oximetry
  • Panel Meters
  • Photodiode Sensor Interface
  • Power Meters
  • Programmable Logic Controllers (PLCs)
Part NumberAmps.Rail to RailVSUPPLY (Total)
ICC per Amp.
Low Input Bias CMOS InputsInput IBIAS
Unity Gain BW
Slew Rate
minmaxtypmaxtyptypmaxtyptyp<See Notes
MAX9945 1Output Only4.7538400500094100Yes0.0001532.215
$0.93 @1k
See All Operational Amplifiers (174)
Pricing Notes:
This pricing is BUDGETARY, for comparing similar parts. Prices are in U.S. dollars and subject to change. Quantity pricing may vary substantially and international prices may differ due to local duties, taxes, fees, and exchange rates. For volume-specific and version-specific prices and delivery, please see the price and availability page or contact an authorized distributor.

MAX9945EVKIT: Evaluation Kit for the MAX9945

Technical Documents

App Note 5129 Stabilize Your Transimpedance Amplifier
Tutorial 4699 Overview of Sensor Signal Paths
Tutorial 4671 Improve Sensor Performance and SNR in Pulse Oximeter Designs

Quality and Environmental Data

Product Reliability Reports: MAX9945.pdf 
Lead-Free Package Tin (Sn) Whisker Reports

CAD Symbols and Footprints

  • MAX9945ATT+
  • MAX9945ATT+T
  • MAX9945AUA+
  • MAX9945AUA+T
  • Device   Fab Process   Technology   Sample size   Rejects   FIT at 25°C   FIT at 55°C  

    Note : The failure rates are summarized by technology and mapped to the associated material part numbers. The failure rates are highly dependent on the number of units tested.

    Quality Management System >
    Environmental Management System >


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