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MAX127, MAX127A, MAX127B, MAX128, MAX128A, MAX128B

Multirange, +5V, 12-Bit DAS with 2-Wire Serial Interface

First 2-Wire 12-Bit, 8-Channel, Serial ADCs Have +/-17V Fault-Protected Inputs
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The MAX127/MAX128 are multirange, 12-bit data acquisition systems (DAS) that require only a single +5V supply for operation, yet accept signals at their analog inputs that may span above the power-supply rail and below ground. These systems provide eight analog input channels that are independently software programmable for a variety of ranges: ±10V, ±5V, 0 to +10V, 0 to +5V for the MAX127; and ±VREF, ±VREF/2, 0 to +VREF, 0 to +VREF/2 for the MAX128. This range switching increases the effective dynamic range to 14 bits and provides the flexibility to interface 4-20mA, ±12V, and ±15V-powered sensors directly to a single +5V system. In addition, these converters are fault protected to ±16.5V; a fault condition on any channel will not affect the conversion result of the selected channel. Other features include a 5MHz bandwidth track/hold, an 8ksps throughput rate, and the option of an internal 4.096V or external reference.

The MAX127/MAX128 feature a 2-wire, I²C*-compatible serial interface that allows communication among multiple devices using SDA and SCL lines.

A hardware shutdown input (active-low SHDN) and two software-programmable power-down modes (standby and full power-down) are provided for low-current shutdown between conversions. In standby mode, the reference-buffer remains active, eliminating start-up delays.

The MAX127/MAX128 are available in 24-pin DIP or space-saving 28-pin SSOP packages.

Data Sheet

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Key Features

  • 12-Bit Resolution, 1/2 LSB Linearity
  • +5V Single-Supply Operation
  • I²C-Compatible, 2-Wire Serial Interface
  • Four Software-Selectable Input Ranges
    • MAX127: 0 to +10V, 0 to +5V, ±10V, ±5V
    • MAX128: 0 to +VREF, 0 to +VREF/2, ±VREF, ±VREF/2
  • 8 Analog Input Channels
  • 8ksps Sampling Rate
  • ±16.5V Overvoltage-Tolerant Input Multiplexer
  • Internal 4.096V or External Reference
  • Two Power-Down Modes
  • 24-Pin Narrow DIP or 28-Pin SSOP Packages


  • Battery-Powered Applications
  • Data Acquisition
  • Industrial Control Systems
  • Robotics

Key Specifications:

Precision ADCs (< 5Msps)
Part Number Resolution
Input Chan. Conv. Rate
ADC Architecture Data Bus Diff/S.E. Input Internal VREF
External VREF
External VREF
Unipolar VIN
Bipolar VIN
ADC max nominal min max max max See Notes
MAX127  12 8 8 SAR I2C S.E. Only 4.096 2.4 4.18 10 10 70 70 $13.94 @1k
MAX128  4.096 2.048 - $11.57 @1k
See All Precision ADCs (< 5Msps) (455)

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.


MAX127, MAX127A, MAX127B, MAX128, MAX128A, MAX128B: Typical Operating Circuit
Typical Operating Circuit

Notes and Comments

Multi-range, 12 bit, 2-wire interface

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Information Index

Document Ref.: 19-4773 Rev 0; 1998-07-01
This page last modified: 2007-07-20