Analog Devices Inc./Maxim Integrated MAX155BEWI+

Overview

The MAX155BEWI+ from Maxim Integrated is an 8-channel, 8-bit analog-to-digital converter with simultaneous track-and-hold (T/H) inputs, 3.6µs per-channel conversion time, internal 2.5V reference, and ±5V dual-supply or +5V single-supply operation-designed for phase-sensitive data acquisition in vibration analysis and DSP front-ends.

For engineers reviewing the MAX155BEWI+ datasheet, MAX155BEWI+ pinout, MAX155BEWI+ application, or MAX155BEWI+ equivalent, this page delivers verified specifications, validated pin functions, confirmed mixed-mode input configuration support (unipolar/bipolar, single-ended/differential), and real-world timing behavior under I/O and hard-wired modes.

Technical Context

The MAX155BEWI+ integrates eight independent track-and-hold amplifiers sampling all channels simultaneously on WR falling edge, feeding a successive-approximation ADC core. Conversion results are stored in an internal 8×8 RAM with addressable read access via D0–D2 (A0–A2) and RD pulses.

It supports two operational modes: I/O mode (MODE open-circuit) for programmable channel selection, input polarity, and topology via configuration register writes; and hard-wired mode (MODE tied high/low with VSS) for fixed 4- or 8-channel conversions without register programming-enabling deterministic latency and simplified interface design.

Key Specifications

Pinout & Package

The MAX155BEWI+ is packaged in a 28-pin wide SO (SOIC-W) surface-mount package with 0.3-inch body width and standard 1.27 mm pitch.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar multichannel simultaneous-sampling ADC applications.

Compared with ADS8556IPM and AD7656ASTZ, the MAX155BEWI+ uniquely delivers 8-channel simultaneous sampling at 8-bit resolution with per-channel bipolar/single-ended configurability and integrated reference in a compact 28-pin SO package-making it optimal for cost-sensitive, space-constrained phase-coherent acquisition systems.

Availability

MAX155BEWI+ is available at Aetrix Electronics and suitable for vibration analysis systems, AC power meters, portable data loggers, and DSP analog front-ends requiring stable component supply and long-term production continuity.

Supply support for MAX155BEWI+ 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 MAX155BEWI+ belongs to Maxim's high-speed data acquisition product line, engineered specifically for applications demanding simultaneous multi-channel sampling with minimal inter-channel skew and integrated signal conditioning.

FAQ

What is the maximum clock frequency supported by the MAX155BEWI+?

The MAX155BEWI+ operates with an external clock frequency ranging from 0.5 MHz to 5.0 MHz. At 5 MHz, the device achieves its specified 3.6 µs per-channel conversion time. Clock frequencies below 5 MHz increase conversion time linearly-e.g., at 2.5 MHz, conversion time extends to ~7.2 µs. The MAX155BEWI+ does not include an internal oscillator and relies entirely on the externally applied CLK signal for timing control.

Does the MAX155BEWI+ require external track-and-hold circuitry?

No, the MAX155BEWI+ does not require external track-and-hold circuitry. It integrates eight independent, matched track-and-hold amplifiers-one per analog input channel-that sample all channels simultaneously on the falling edge of the WR signal. This internal T/H architecture eliminates external component count and ensures sub-4 ns channel-to-channel aperture delay matching, which is critical for phase-coherent multi-sensor acquisition.

How does the MAX155BEWI+ handle bipolar input signals?

The MAX155BEWI+ supports bipolar input operation by connecting VSS to –5V and setting the BIP bit (D5) to 1 in the configuration register. With VSS = –5V and internal 2.5V reference, the analog input range becomes ±2.5V relative to AGND. Input signals must remain within (VSS – 0.3V) to (VDD + 0.3V), i.e., –5.3V to +5.3V. The MAX155BEWI+ guarantees ±2 LSB bipolar offset error over the full operating temperature range.

Can the MAX155BEWI+ be used with an external voltage reference?

Yes, the MAX155BEWI+ accepts an external reference voltage applied to the REFIN pin, specified for 2.375V to 2.625V. When using an external reference, REFOUT must be either bypassed to AGND with a 4.7µF + 0.1µF capacitor or disabled by connecting it to VDD. Disabling REFOUT increases power-down current by ~250 µA but eliminates need for bypass components. The MAX155BEWI+ maintains full accuracy specifications with valid external reference input.

What is the function of the MODE pin on the MAX155BEWI+?

The MODE pin on the MAX155BEWI+ selects between two interface architectures: when left open-circuit, it enables I/O mode-allowing full programmability of channel selection, input topology, and conversion sequence via the configuration register; when tied high or low with VSS, it activates hard-wired mode-selecting fixed 4- or 8-channel conversions without register writes. In hard-wired mode, D0–D7 inputs are ignored, simplifying microcontroller firmware and guaranteeing deterministic timing behavior.