Analog Devices Inc./Maxim Integrated MAX145BEUA+

Overview

MAX145BEUA+ from Maxim Integrated is a -40°C to +85°C, 12-bit pseudo-differential successive-approximation ADC in 8-pin µMAX package, operating from +2.7V to +5.25V supply, delivering 108ksps sampling rate with 7.4µs conversion time and SPI/QSPI/MICROWIRE-compatible 3-wire serial interface. It features internal track/hold, automatic power-down (0.2µA), fast wake-up (2.5µs), and on-chip clock - optimized for portable data logging and isolated data acquisition where low power and space-constrained PCB layout are critical.

For engineers reviewing the MAX145BEUA+ datasheet, MAX145BEUA+ pinout, MAX145BEUA+ application, or MAX145BEUA+ equivalent, this page delivers verified electrical parameters, validated µMAX pin mapping, confirmed pseudo-differential input behavior, real-world dynamic performance (SINAD = 70dB, SFDR = 80dB), and two production-ready alternative parts with documented functional and packaging differences.

Technical Context

The MAX145BEUA+ implements a SAR architecture with integrated track-and-hold, accepting pseudo-differential inputs (CH+, CH−) where only CH+ is sampled while CH− must remain stable within ±0.5LSB relative to GND. Its analog front-end includes 9kΩ input resistance, 16pF input capacitance, and internal protection diodes enabling ±300mV overvoltage tolerance.

Conversion is initiated by CS/SHDN falling edge, with clock mode selected dynamically: SCLK high at CS/SHDN transition enables internal 2MHz oscillator (±20%), while SCLK low selects external clock (100kHz–2.17MHz). Data output follows MSB-first 16-bit format: three leading '1's, channel ID bit, then 12 data bits - compatible with SPI (CPOL=0, CPHA=0), QSPI, and MICROWIRE protocols.

Key Specifications

Pinout & Package

MAX145BEUA+ is housed in an 8-pin µMAX package (U8-1 code), 3mm × 3mm body, 0.5mm lead pitch, exposed pad for thermal enhancement. Pinout is identical to MAX144 series but configured for pseudo-differential 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, MAX145BEUA+ uniquely combines 108ksps throughput, 0.2µA shutdown, pseudo-differential input, and triple-protocol serial interface in a 3mm × 3mm package - making it the only option meeting simultaneous constraints of portable power budget, noise rejection, and microcontroller driver reuse.

Availability

MAX145BEUA+ is available at Aetrix Electronics and suitable for portable data logging, isolated data acquisition, and medical instrumentation requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for MAX145BEUA+ 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 demanding industrial, medical, and communications applications - emphasizing integration, reliability, and low-power innovation.

The MAX144/MAX145 family was engineered specifically for space- and power-constrained data acquisition systems requiring true 12-bit accuracy without external support components - targeting battery-operated test equipment and distributed sensor networks.

FAQ

What is the maximum sampling rate supported by MAX145BEUA+?

The MAX145BEUA+ supports a maximum sampling rate of 108ksps, achieved using the external clock mode with SCLK frequency set to 2.17MHz. At this rate, conversion time is fixed at 7.4µs, and the device maintains specified INL (±1 LSB) and dynamic performance (SINAD = 70dB). Slower rates reduce current consumption linearly - e.g., 10ksps draws 100µA at +3V.

Does MAX145BEUA+ require an external reference voltage?

Yes, MAX145BEUA+ requires an external reference voltage applied to the REF pin. The device accepts VREF from 0V to VDD + 50mV, with optimal performance at 2.5V. The reference must deliver ≥250µA DC load current and exhibit ≤10Ω output impedance; a 0.1µF ceramic capacitor is mandatory at the REF pin for stability and noise reduction.

How does the pseudo-differential input of MAX145BEUA+ differ from true differential operation?

The MAX145BEUA+ implements pseudo-differential input: only CH+ (Pin 2) is actively sampled, while CH− (Pin 3) serves as a stable reference node that must remain within ±0.5LSB of GND. Unlike true differential ADCs, it does not measure the voltage difference between CH+ and CH− - instead, CH− sets the common-mode baseline for CH+ sampling, providing partial noise rejection without differential amplifier complexity.

Can MAX145BEUA+ interface directly with a Raspberry Pi GPIO header?

Yes, MAX145BEUA+ can interface directly with Raspberry Pi's hardware SPI peripheral. Configure the Pi's SPI0 interface with CPOL = 0 and CPHA = 0, connect CS/SHDN to GPIO (software-controlled), SCLK/DOUT to MOSI/SCLK pins, and ensure VDD = 3.3V. No level shifters are needed, and the 0.2µA shutdown current enables Pi-controlled deep-sleep modes between acquisitions.

What is the wake-up time from shutdown for MAX145BEUA+?

The MAX145BEUA+ wake-up time from shutdown is 2.5µs when the external reference is stable to within 1LSB. If the reference requires longer stabilization (e.g., after cold start), wake-up time must be extended accordingly - the device begins conversion on the falling edge of CS/SHDN, so system firmware must delay SCLK activation until reference settles to avoid gain/offset errors.