Analog Devices Inc./Maxim Integrated MAX11212AEUB+

Overview

MAX11212AEUB+ from Maxim Integrated is an 18-bit, single-channel, ultra-low-power delta-sigma ADC optimized for high-dynamic-range sensor measurement in 4–20mA industrial loops. It delivers 120sps output rate, <240µA active current, 3ppm INL, and integrated 2.4576MHz oscillator - enabling precision analog-to-digital conversion without external timing components in battery- or loop-powered systems.

For engineers reviewing the MAX11212AEUB+ datasheet, MAX11212AEUB+ pinout, MAX11212AEUB+ application, or MAX11212AEUB+ equivalent, key selection considerations include its 2-wire serial interface timing, differential input/reference architecture, sleep-mode power management (<0.1µA), 50/60Hz line-noise rejection (>80dB), and µMAX package compatibility with space-constrained industrial sensor nodes.

Technical Context

The MAX11212AEUB+ implements a third-order delta-sigma modulator paired with an on-chip SINC4 digital filter, delivering 18-bit noise-free resolution at 120sps with 720nVRMS noise (B variant) - though the A variant achieves 2.1µVRMS thermal noise. Its internal 2.4576MHz oscillator eliminates external crystal requirements while maintaining ±0.1% frequency stability over temperature.

It supports fully differential analog inputs (AINP/AINN) and reference inputs (REFP/REFN), with common-mode rejection >90dB DC and >90dB at 50Hz. The 2-wire interface uses only SCLK and RDY/DOUT pins, where RDY/DOUT serves dual roles: data-ready flag and MSB-first serial data output synchronized to SCLK rising edges.

Key Specifications

Pinout & Package

MAX11212AEUB+ is housed in a lead(Pb)-free, RoHS-compliant 10-pin µMAX® package (outline 21-0061, code U10+2), measuring 3mm × 3mm × 0.8mm with exposed pad for thermal enhancement.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar high-resolution, low-power ADC applications.

Compared with MAX11212BEUB+, the MAX11212AEUB+ trades lower noise for 8.7× faster output rate and higher clock frequency - making it better for real-time loop control. Against ADS1220IPWR, it offers simpler 2-wire timing and built-in oscillator at the cost of no PGA or burnout current, favoring applications where sensor signal level is stable and external timing is undesirable.

Availability

MAX11212AEUB+ is available at Aetrix Electronics and suitable for industrial sensor transmitters, portable instrumentation, and battery-powered measurement systems requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for MAX11212AEUB+ 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 high-frequency ICs for industrial, medical, and communications applications - emphasizing integration, low power, and robustness.

The MAX11212AEUB+ belongs to Maxim's ultra-low-power delta-sigma ADC family, engineered specifically for high-accuracy, low-power sensor digitization in constrained environments like 4–20mA loops and portable test equipment.

FAQ

What is the maximum sampling rate of the MAX11212AEUB+?

The MAX11212AEUB+ operates at a fixed output data rate of 120 samples per second (sps), as specified in the ordering information and confirmed in the Electrical Characteristics table. This rate is determined by its internal 2.4576MHz oscillator and SINC4 filter configuration - not user-programmable. The MAX11212AEUB+ does not support variable data rates; for lower-speed, lower-noise operation, the MAX11212BEUB+ variant (13.75sps) is available.

Does the MAX11212AEUB+ require an external crystal or oscillator?

No, the MAX11212AEUB+ integrates a factory-trimmed 2.4576MHz internal oscillator that requires no external components - a key feature highlighted in both the General Description and Detailed Description sections. External clock input (pin 10, CLK) is optional and disables the internal oscillator when driven; it is not required for normal operation. This simplifies design, reduces BOM count, and improves reliability in space-constrained applications.

How does the 2-wire serial interface of the MAX11212AEUB+ work?

The MAX11212AEUB+ uses only two pins - SCLK (pin 9) and RDY/DOUT (pin 8) - for communication. RDY/DOUT asserts low when conversion data is ready; applying SCLK pulses then shifts out 18-bit two's complement data MSB-first on each rising edge. A 25th SCLK pulse returns RDY/DOUT to high idle state. This interface eliminates dedicated chip-select or data-direction control lines, reducing MCU GPIO usage and PCB routing complexity compared to SPI or I²C.

What is the purpose of the dual supply rails (AVDD and DVDD) on the MAX11212AEUB+?

The MAX11212AEUB+ separates analog (AVDD, 2.7–3.6V) and digital (DVDD, 1.7–3.6V) supplies to minimize digital switching noise coupling into sensitive analog circuitry. This isolation preserves SNR and INL performance - critical for 18-bit accuracy. Each rail requires its own 0.1µF ceramic bypass capacitor placed near the respective pin. Independent voltage ranges also allow optimization: e.g., DVDD can run at 1.8V to reduce digital current while AVDD remains at 3.3V for full analog headroom.

Can the MAX11212AEUB+ perform self-calibration, and how is it triggered?

Yes, the MAX11212AEUB+ supports on-demand offset and gain self-calibration. It is triggered by applying a 26th SCLK pulse immediately after reading the 18-bit conversion result (i.e., after the 25th pulse that pulls RDY/DOUT high). Calibration begins on the falling edge of that 26th pulse and completes automatically - no host software intervention is needed beyond the clock sequence. This feature compensates for temperature- and supply-induced drift, ensuring long-term accuracy without external calibration equipment.