Features and Benefits

  • Single Supply +2.5V to +7.0V Operation
  • Measures Both Positive and Negative Input Voltages
  • Charge-Pump Voltage Inverter Generates a Negative Supply Voltage
  • Internal Bandgap Reference
  • On-Board Display Driver
  • Low Segment Current (MAX140)

Product Details

The MAX138/MAX139 are 3 ½ digit A/D converters (ADCs) with on-board LCD (MAX138) and LED (MAX139) display drivers. The MAX138/MAX139 also contain a charge-pump voltage inverter. The charge-pump inverter allows the MAX138/MAX139 to measure both positive and negative input voltages while operating from a single power-supply voltage from +2.5V to +7V. The operating circuits of the MAX138/MAX139 are similar to those of the ICL7136 and ICL7137 respectively, except the MAX138/MAX139 have an internal oscillator and an external charge-pump capacitor connected to pins 38 and 40.

MAX140 is a low segment-current version of the MAX139 intended for use with low-current LED displays.


  • +3V Powered DMMs
  • +5V Powered Panel Meters
  • Digital Thermometers
  • Instruments
  • Portable Monitors
  • Weigh Scales

Product Lifecycle icon-recommended Production

At least one model within this product family is in production and available for purchase. The product is appropriate for new designs but newer alternatives may exist.

Product Recommendations

MAX138 Companion Parts

Recommended Related Parts

Design Resources

ADI has always placed the highest emphasis on delivering products that meet the maximum levels of quality and reliability. We achieve this by incorporating quality and reliability checks in every scope of product and process design, and in the manufacturing process as well.  "Zero defects" for shipped products is always our goal.

PCN-PDN Information

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