1µA, 4-Bump UCSP/SOT23, Precision Current-Sense Amplifier

Industry's Smallest Current-Sense Amplifier: 1mm x 1mm with ICC < 1µA, VOS < 500µV, Gain Error < 0.5%


The MAX9938 high-side current-sense amplifier offers precision accuracy specifications of VOS less than 500µV (max) and gain error less than 0.5% (max). Quiescent supply current is an ultra-low 1µA. The MAX9938 fits in a tiny, 1mm x 1mm UCSP™ package size or a 5-pin SOT23 package, making the part ideal for applications in notebook computers, cell phones, PDAs, and all battery-operated portable devices where accuracy, low quiescent current, and small size are critical.

The MAX9938 features an input common-mode voltage range from 1.6V to 28V. These current-sense amplifiers have a voltage output and are offered in four gain versions: 25V/V (MAX9938T), 50V/V (MAX9938F), 100V/V (MAX9938H), and 200V/V (MAX9938W).

The four gain selections offer flexibility in the choice of the external current-sense resistor. The very low 500µV (max) input offset voltage allows small 25mV to 50mV full-scale VSENSE voltage for very low voltage drop at full-current measurement.

The MAX9938 is offered in tiny 4-bump, UCSP (1mm x 1mm x 0.6mm footprint), 5-pin SOT23, and 6-pin µDFN (2mm x 2mm x 0.8mm) packages specified for operation over the -40°C to +85°C extended temperature range.
MAX9938: Typical Operating Circuit MAX9938: Typical Operating Circuit Enlarge+

Key Features

  • Ultra-Low Supply Current of 1µA (max)
  • Low 500µV (max) Input Offset Voltage
  • Low < 0.5% (max) Gain Error
  • Input Common Mode: +1.6V to +28V
  • Voltage Output
  • Four Gain Versions Available
    • 25V/V (MAX9938T)
    • 50V/V (MAX9938F)
    • 100V/V (MAX9938H)
    • 200V/V (MAX9938W)
  • Tiny 1mm x 1mm x 0.6mm, 4-Bump UCSP, 5-Pin SOT23, or 2mm x 2mm x 0.8mm, 6-Pin µDFN Packages


  • Cell Phones
  • Notebook Computers
  • PDAs
  • Portable/Battery-Powered Systems
  • Power Management Systems
Part Number Output Format CMVR
Bi-Dir. Curr. Sense VSENSE_FS
VOS @25°C
Gain Gain Accuracy @25°C
Oper. Temp.
min max min max typ recomm. max max @ -3dB See Notes
MAX9938  Voltage 1.6 28 1.6 28 1 No
25 V/V
50 V/V
100 V/V
200 V/V
0 -40 to +85 $0.65 @1k
See All Current Sense Amplifiers (42)
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.

MAX9938EVKIT: Evaluation Kit for the MAX9938

Tools & Models

MAX9938T Macromodel
MAX9938H Macromodel
MAX9938F Macromodel
MAX9938T Orcad Library
MAX9938H Orcad Library
MAX9938F Orcad Library
MAX9938 Orcad Library


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