Analog Devices Inc./Maxim Integrated MAX156ACWI

Overview

MAX156ACWI from Maxim Integrated is a high-speed, 4-channel, 8-bit analog-to-digital converter (ADC) with simultaneous track-and-hold (T/H) inputs, 3.6µs per-channel conversion time, internal 2.5V reference, and support for unipolar/bipolar and single-ended/differential input configurations. It operates from single +5V or dual ±5V supplies and targets precision data-acquisition systems requiring synchronized sampling across multiple analog channels.

For engineers reviewing the MAX156ACWI datasheet, MAX156ACWI pinout, MAX156ACWI application, or MAX156ACWI equivalent, this page delivers verified technical context, real-world interface timing constraints, confirmed package mapping to 24-pin narrow PDIP, validated channel-matching accuracy (±½ LSB), and selection guidance among functionally aligned alternatives for vibration analysis, AC power metering, and DSP front-end designs.

Technical Context

The MAX156ACWI implements a successive-approximation ADC core with four independent track-and-hold amplifiers that sample all enabled analog inputs simultaneously on the falling edge of WR. Its internal 2.5V reference (REFOUT) is buffered and requires 4.7µF + 0.1µF bypassing to AGND for stability.

Configuration is handled via an 8-bit bidirectional I/O port (D0–D7 shared with A0–A2 address bits), where MODE = open-circuit enables full programmability of input type (single-ended/differential), polarity (unipolar/bipolar), power-down, and channel selection - with BIP/DIFF changes taking effect on the subsequent conversion cycle.

Key Specifications

Pinout & Package

MAX156ACWI is housed in a 24-pin narrow plastic DIP (PDIP) package with 0.3-inch body width and through-hole mounting. Pin 1 is marked by a notch or dot; pin numbering follows standard counter-clockwise convention from top view.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX156ACWI, ADS7822U offers smaller footprint and lower power but sacrifices simultaneous sampling and channel count, while MAX11607EEE+ provides higher resolution and more channels at the cost of timing coherence and speed - making MAX156ACWI uniquely suited for time-critical, multi-signal synchronization tasks.

Availability

MAX156ACWI is available at Aetrix Electronics and suitable for phase-sensitive data acquisition, vibration analysis systems, and AC power meters requiring stable component supply with guaranteed long-term industrial availability.

Supply support for MAX156ACWI 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 high-performance analog and mixed-signal ICs for industrial, automotive, and communications applications, emphasizing integration, precision, and reliability.

The MAX155/MAX156 product line was engineered specifically for high-fidelity, multi-channel data acquisition systems demanding synchronized sampling, on-chip reference, and flexible input configuration - targeting test equipment, energy monitoring, and real-time signal analysis.

FAQ

What is the maximum clock frequency supported by the MAX156ACWI?

The MAX156ACWI supports an external clock frequency range of 0.5 MHz to 5.0 MHz. At 5 MHz, the device achieves its specified 3.6 µs per-channel conversion time. Operating below 0.5 MHz increases conversion latency proportionally and may affect timing margins for WR/RD handshaking sequences in high-throughput applications.

Does the MAX156ACWI require an external reference, or can it operate using only its internal 2.5V reference?

The MAX156ACWI can operate fully using its internal 2.5 V reference (available at REFOUT), which is factory-trimmed and specified for ±100 ppm/°C drift over -40°C to +85°C. An external reference may be applied at REFIN only if higher initial accuracy or custom voltage is needed; in that case, REFOUT must be bypassed or tied to VDD to prevent oscillation.

How does the MAX156ACWI handle simultaneous sampling across its four analog inputs?

The MAX156ACWI uses four independent track-and-hold amplifiers, each dedicated to one analog input (AIN0–AIN3). All four T/Hs sample their respective inputs simultaneously on the falling edge of the WR signal, ensuring sub-4 ns aperture delay matching - a key requirement for coherent multi-channel waveform capture in the MAX156ACWI.

Can the MAX156ACWI perform both unipolar and bipolar conversions in the same multichannel sequence?

Yes - the MAX156ACWI supports mixed-mode operation. Each channel's configuration (unipolar/bipolar, single-ended/differential) is set independently via the D5/BIP and D6/DIFF bits in the configuration register before conversion. For example, AIN0 can be unipolar single-ended while AIN1 is bipolar differential within the same WR-initiated sequence.

What is the purpose of the INH (Inhibit) bit (D4) in the MAX156ACWI configuration register?

The INH bit (D4) in the MAX156ACWI allows loading of new configuration data into the register without triggering a conversion. When INH = 1, a WR pulse updates the register but does not start sampling. This enables safe reconfiguration - such as changing channel selections or input modes - prior to initiating the next conversion with INH = 0.