Analog Devices Inc./Maxim Integrated MAX1273CUA+

Overview

The MAX1273CUA+ from Maxim Integrated is a fault-protected, software-programmable 12-bit analog-to-digital converter (ADC) with ±VREF and 0 to VREF/2 input ranges, internal 4.096V reference, SPI/QSPI/MICROWIRE-compatible 3-wire interface, and 87ksps throughput-designed for industrial data-acquisition systems interfacing 4–20mA sensors in single 5V supply environments.

For engineers reviewing the MAX1273CUA+ datasheet, MAX1273CUA+ pinout, MAX1273CUA+ application, or MAX1273CUA+ equivalent, key selection considerations include its software-selectable bipolar/unipolar input scaling, ±6V absolute maximum analog input rating, 12-bit no-missing-codes performance, and µMAX-8 package compatibility with space-constrained PCB layouts.

Technical Context

The MAX1273CUA+ uses successive approximation register (SAR) architecture with integrated track-and-hold, supporting four programmable input ranges via RNG/BIP control bits. Its analog front-end includes resistor-divider scaling and overvoltage protection up to ±6V on AIN.

Conversion timing is synchronized to an external SCLK (0.1–1.4MHz), requiring 16 clocks per conversion (87ksps max). The serial interface outputs MSB-first on DOUT's falling edge and accepts 8-bit control bytes with START, RNG, BIP, PD, MODE1/MODE0, REF bits to configure range, polarity, power-down, and reference mode.

Key Specifications

Pinout & Package

The MAX1273CUA+ is housed in an 8-pin µMAX® package (2.1mm × 2.1mm, 0.5mm pitch), specified for operation from -40°C to +85°C. Pinout is validated per Maxim's official datasheet revision 3 (12/2011).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 12-bit multirange ADC applications.

Compared with ADS7816U and MAX11602EUA+, the MAX1273CUA+ delivers unique integration of software-configurable input scaling, ±6V fault protection, and internal 4.096V reference - reducing component count and improving robustness in industrial and portable instrumentation where sensor variety and field reliability are paramount.

Availability

MAX1273CUA+ is available at Aetrix Electronics and suitable for industrial process monitoring, robotics motor control, portable medical instrumentation, and automated test equipment requiring stable component supply and long-term manufacturability.

Supply support for MAX1273CUA+ includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Maxim Integrated (now part of Analog Devices) designs precision analog, mixed-signal, and power-management ICs for industrial, automotive, and communications applications.

The MAX1272/MAX1273 product line targets rugged, low-power data-acquisition systems requiring software-configurable input ranges, fault protection, and seamless microcontroller integration via standard serial interfaces.

FAQ

What input voltage ranges does the MAX1273CUA+ support?

The MAX1273CUA+ supports four software-selectable input ranges: ±VREF, ±VREF/2, 0 to VREF, and 0 to VREF/2. With its internal 4.096V reference, this translates to ±4.096V, ±2.048V, 0–4.096V, and 0–2.048V full-scale ranges. These are configured using the RNG and BIP bits in the 8-bit control byte, enabling direct interface to diverse analog sensors without external scaling resistors.

Does the MAX1273CUA+ include an internal voltage reference?

Yes, the MAX1273CUA+ integrates a factory-trimmed 4.096V internal reference with ±15ppm/°C temperature coefficient. When enabled via the REF bit in the control byte, it drives the REF pin and eliminates the need for an external reference IC. A 1.0μF capacitor must be placed from REF to GND for stability. External references from 2.40V to 4.18V are also supported when the internal buffer is disabled.

What is the absolute maximum analog input voltage rating for the MAX1273CUA+?

The MAX1273CUA+ has an absolute maximum analog input (AIN) rating of ±6V relative to GND. This is distinct from the MAX1272 (±12V) and reflects its optimized design for systems using lower-voltage references like ±4.096V. Exceeding ±6V may cause permanent damage, though the device includes overvoltage protection circuitry that limits input current to under 2mA during transient events.

How does the MAX1273CUA+ achieve 87ksps sampling rate?

The MAX1273CUA+ achieves 87ksps by executing each conversion in 16 SCLK cycles at the maximum rated clock frequency of 1.4MHz. Acquisition takes 4 clocks, conversion 12 clocks, and the interface remains active between conversions. To sustain 87ksps, CS must remain low and the next control byte must be sent after bit D4 of the prior conversion appears on DOUT - minimizing inter-conversion dead time.

What power-down modes are available on the MAX1273CUA+?

The MAX1273CUA+ offers four software-programmable power-down modes controlled by PD, MODE1, and MODE0 bits: delayed standby, immediate standby, delayed full power-down, and immediate full power-down. Standby modes retain the internal reference buffer (enabling fast wake-up), while full power-down disables it. Supply current drops to 0.2mA at 1ksps in standby and 1μA in full shutdown - critical for battery-powered instruments using the MAX1273CUA+.