MAX138

PRODUCTION

3 1/2 Digit ADC with Reference, Charge Pump, and Direct LED Drivers

Operates with Single +2.5V to +7V Supply, Accepts Bipolar Inputs

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Overview

  • 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)

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.

Applications

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

MAX138
3 1/2 Digit ADC with Reference, Charge Pump, and Direct LED Drivers
MAX138, MAX139, MAX140: Typical Operating Circuit
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Hardware Ecosystem

Parts Product Life Cycle Description
Analog to Digital Converters (ADCs) 1
MAX140 PRODUCTION 3 1/2 Digit ADC with Reference, Charge Pump, and Direct LED Drivers
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