Analog Devices Inc./Maxim Integrated MAX145AEUA+

Overview

MAX145AEUA+ from Maxim Integrated is a low-power, 12-bit successive-approximation analog-to-digital converter (SAR ADC) with pseudo-differential input architecture, 108ksps sampling rate, ±0.5 LSB INL, and operation from +2.7V to +5.25V supply. It features an on-chip track/hold, SPI/QSPI/MICROWIRE-compatible 3-wire serial interface, and operates across –40°C to +85°C for industrial data acquisition.

For engineers reviewing the MAX145AEUA+ datasheet, MAX145AEUA+ pinout, MAX145AEUA+ application, or MAX145AEUA+ equivalent, this device is selected for battery-powered instrumentation requiring high-resolution digitization of differential sensor signals with minimal power and board space - especially where fast wake-up (2.5µs), automatic shutdown (0.2µA), and µMAX package integration are critical.

Technical Context

The MAX145AEUA+ implements a 12-bit SAR conversion core with integrated track-and-hold, accepting pseudo-differential inputs (CH+, CH–) referenced to GND, where CH– must remain stable within ±0.5 LSB during acquisition. Its internal clock supports 0–5MHz serial data transfer, while external clock mode enables precise timing control at 100kHz–2.17MHz with 7.4µs conversion time.

It uses a 16pF hold capacitor and 9kΩ input resistance, with acquisition time calculable as t_ACQ = 9(R_S + 9kΩ)·16pF. The device delivers 70dB SINAD, –85dB channel crosstalk, and 1MHz full-power bandwidth - enabling undersampling of periodic signals while maintaining DC accuracy via external reference (0–V_DD+50mV).

Key Specifications

Pinout & Package

MAX145AEUA+ is housed in an 8-pin µMAX® package (U8-1), 3mm × 3mm, exposed pad, thin-profile surface-mount package rated for –40°C to +85°C operation.

Key Features

Applications

Equivalent & Alternatives

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

Compared with ADS7816U and AD7476ARTZ-REEL7, the MAX145AEUA+ uniquely combines pseudo-differential input, internal track/hold, automatic 0.2µA shutdown, and dual-clock-mode flexibility - making it the only option among the three qualified for low-power, noise-sensitive, differential sensor digitization in compact industrial designs.

Availability

MAX145AEUA+ is available at Aetrix Electronics and suitable for portable data logging, battery-powered instrumentation, isolated data acquisition, process-control monitoring, and medical sensor interfaces requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for MAX145AEUA+ 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) is a semiconductor company specializing in high-performance analog, mixed-signal, and power-management ICs for industrial, automotive, and communications applications.

The MAX144/MAX145 product line was designed specifically for space-constrained, low-power data acquisition systems requiring 12-bit resolution, fast wake-up, and robust serial interfacing - targeting portable test equipment and distributed sensor networks.

FAQ

What is the input configuration supported by the MAX145AEUA+?

The MAX145AEUA+ supports pseudo-differential analog input: CH0 (CH+) is the sampled signal node, while CH1 (CH–) serves as the stable reference return path. Unlike true differential ADCs, only CH+ is actively sampled; CH– must remain within ±0.5 LSB of GND during conversion, typically achieved using a 0.1µF capacitor to ground. This architecture rejects common-mode noise without requiring matched input drivers.

Does the MAX145AEUA+ include an internal reference voltage source?

No, the MAX145AEUA+ requires an external reference voltage applied to the REF pin. It accepts 0V to V_DD+50mV, with recommended 2.5V for full 12-bit performance. The device draws up to 250µA from REF during conversion and specifies minimum 18kΩ input resistance. A 0.1µF ceramic capacitor must be placed directly at the REF pin for optimal noise rejection and stability.

How does the MAX145AEUA+ enter and exit shutdown mode?

The MAX145AEUA+ enters shutdown automatically when CS/SHDN is pulled high (V_DD), reducing supply current to 0.2µA typical. To exit shutdown, pull CS/SHDN low; the device wakes up in 2.5µs and begins tracking on the falling edge. If the external reference is unstable, wake-up time must be extended to allow REF settling to within 1 LSB - verified in the MAX145AEUA+ datasheet timing diagrams.

What serial interface protocols is the MAX145AEUA+ compatible with?

The MAX145AEUA+ supports SPI, QSPI, and MICROWIRE protocols via its 3-wire interface (CS/SHDN, SCLK, DOUT). It operates with CPOL = 0 and CPHA = 0, outputs data on SCLK's falling edge, and expects sampling on the rising edge. The 16-bit frame includes three leading 1s, channel ID, and 12 MSB-first data bits - fully compliant with standard microcontroller SPI peripherals without bit-banging or protocol translation.

What is the maximum source impedance the MAX145AEUA+ can drive without external buffering?

The MAX145AEUA+ has 9kΩ input resistance and 16pF input capacitance, resulting in a calculated acquisition time t_ACQ = 9(R_S + 9kΩ)·16pF. For R_S ≤ 1kΩ, AC performance remains unaffected. Above 1kΩ, acquisition time increases linearly; for example, at 10kΩ source impedance, t_ACQ ≈ 1.6µs - exceeding the 7.4µs conversion window. In such cases, a 0.01µF capacitor at the input is recommended to form an anti-aliasing RC filter.