Analog Devices Inc./Maxim Integrated MAX156AEWI+

Overview

MAX156AEWI+ from Maxim Integrated is a high-speed, 4-channel, 8-bit analog-to-digital converter (ADC) with simultaneous track-and-hold (T/H) inputs for phase-coherent sampling. It delivers 3.6µs per-channel conversion time, supports unipolar/bipolar and single-ended/differential input modes, features an integrated 2.5V reference, and operates from single +5V or dual ±5V supplies. It is used in vibration analysis, AC power metering, and DSP front-end acquisition systems requiring synchronized multi-channel sampling.

For engineers reviewing the MAX156AEWI+ datasheet, MAX156AEWI+ pinout, MAX156AEWI+ application, or MAX156AEWI+ equivalent, this page provides verified technical context, real-world interface timing behavior, confirmed package mapping to 28-pin wide SO, validated pin functions including mode-configurable data/address multiplexing, and two production-validated alternative parts with documented functional trade-offs.

Technical Context

The MAX156AEWI+ implements a successive-approximation ADC core with eight independent T/H amplifiers-four active and four unused-enabling true simultaneous sampling across all four analog inputs (AIN0–AIN3). Its internal 2.5V reference (REFOUT) is buffered and requires 4.7µF + 0.1µF bypassing for stability, and it supports both hard-wired mode (via MODE/VSS pins) and flexible I/O mode (via configuration register writes).

Interface operation uses bidirectional D0–D7 pins shared between RAM address/data and configuration control (A0–A2, PD, INH, BIP, DIFF, ALL), with WR rising edge updating the configuration register and falling edge initiating simultaneous sampling. BUSY asserts low during conversion; RD pulses sequentially access 4-channel results from internal RAM, with address pointer reset on WR low in multichannel mode.

Key Specifications

Pinout & Package

MAX156AEWI+ is housed in a 28-pin wide SO (Small Outline) package with 300 mil body width, gull-wing leads, and RoHS-compliant matte tin plating. Pin 1 is marked by a beveled corner; pin numbering follows standard SO convention counter-clockwise from pin 1.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 4-channel, 8-bit ADC applications.

Compared with ADS7822U and MAX1166BCAP+, the MAX156AEWI+ uniquely combines simultaneous 4-channel sampling, hardware-selectable bipolar operation, and dual-mode interface flexibility-making it optimal for phase-sensitive, mixed-input industrial acquisition where timing coherence and analog range adaptability are critical.

Availability

MAX156AEWI+ is available at Aetrix Electronics and suitable for vibration analysis systems, AC power metering platforms, and portable data loggers requiring stable component supply, long-term lifecycle support, and guaranteed traceable sourcing.

Supply support for MAX156AEWI+ 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 MAX155/MAX156 product line was designed specifically for high-fidelity, multi-channel data acquisition systems requiring precise timing alignment, on-chip signal conditioning, and flexible input configuration-targeting test equipment, energy metering, and predictive maintenance hardware.

FAQ

What is the maximum sample rate achievable with the MAX156AEWI+ in 4-channel simultaneous mode?

The MAX156AEWI+ completes each 4-channel conversion in 3.6µs per channel, resulting in a total conversion time of 14.4µs for all four channels. This supports a maximum sustained sampling rate of approximately 69.4ksps per channel (1/14.4µs), assuming continuous WR triggering and sufficient RD bandwidth to empty the RAM before the next conversion begins. The actual system rate may be limited by microcontroller read speed and BUSY polling latency.

Does the MAX156AEWI+ support true differential input pairs like AIN0–AIN1, or only pseudo-differential against AGND?

The MAX156AEWI+ supports true differential input pairs: Table 2 and Table 3 in the datasheet confirm that setting DIFF = 1 configures AIN0–AIN1, AIN2–AIN3, etc., as complementary differential inputs with dedicated polarity control. In differential mode, the ADC measures the voltage difference between two analog inputs (e.g., AIN0 minus AIN1), rejecting common-mode noise-unlike pseudo-differential schemes referenced to AGND.

Can the internal 2.5V reference of the MAX156AEWI+ be used while operating from a single +5V supply with VSS = 0V?

Yes. The MAX156AEWI+ functions correctly with VSS = 0V (i.e., single +5V supply) and uses its internal 2.5V reference for both unipolar (0V to 2.5V) and bipolar (±2.5V) conversions. When VSS = 0V, the bipolar range is achieved by offsetting the input signal relative to AGND, and the internal reference remains fully operational and stable, provided the 4.7µF + 0.1µF bypass capacitors are installed on REFOUT.

How does the MODE pin affect configuration register access in the MAX156AEWI+?

When MODE is left open-circuit (I/O mode), the MAX156AEWI+ uses the D0–D7 pins as a bidirectional bus to read RAM data and write to the configuration register (A0–A2, BIP, DIFF, ALL, INH, PD). When MODE is hard-wired low or high, the configuration register is disabled-the device ignores D0–D7 inputs and executes fixed conversions (e.g., 4-channel differential) based solely on MODE and VSS states, simplifying firmware.

Is the MAX156AEWI+ pin-compatible with the MAX155 series, and can they share the same PCB layout?

No. The MAX156AEWI+ uses a 28-pin wide SO package with AIN0–AIN3 on pins 1, 2, 27, 28 and no AIN4–AIN7 connections, whereas the MAX155 occupies the same 28-pin wide SO but routes AIN4–AIN7 to pins 25–28 and relocates other signals (e.g., MODE to pin 5 in MAX156 vs. pin 23 in MAX155). Pinouts differ significantly-PCB layouts are not interchangeable, and direct substitution requires board revision.