Analog Devices Inc./Maxim Integrated MAX321CUA+T

Overview

The MAX321CUA+T from Maxim Integrated is a precision dual-channel normally closed (NC) analog switch operating from ±3V to ±8V dual supplies, delivering 35Ω max on-resistance, <2Ω channel-to-channel R_ON matching, and <100ns turn-off time. It targets low-leakage, low-charge-injection signal routing in ±5V DAC/ADC interfaces and battery-powered test equipment.

For engineers reviewing the MAX321CUA+T datasheet, MAX321CUA+T pinout, MAX321CUA+T application, or MAX321CUA+T equivalent, key selection criteria include guaranteed NC configuration, bipolar supply support, sub-5pC charge injection, 100pA max off-leakage at +85°C, and µMAX-8 package compatibility with space-constrained portable designs.

Technical Context

The MAX321CUA+T implements complementary MOSFET pairs per channel with integrated level-shifting logic to ensure reliable switching across its full ±3V to ±8V supply range. Its NC topology guarantees closed-path continuity when logic input is low (IN = 0V), with break-before-make behavior not applicable-unlike the MAX322.

Designed for precision analog signal routing, it maintains flat on-resistance (<4Ω variation over ±3V signal range) and achieves >72dB off-isolation at 1MHz. Charge injection is tightly controlled (<5pC) via matched transistor sizing and layout symmetry, critical for sample-and-hold accuracy.

Key Specifications

Pinout & Package

MAX321CUA+T uses an 8-pin µMAX package (2.1mm × 1.6mm, 0.5mm pitch), optimized for compact portable and instrumentation PCBs. The package features exposed pad for thermal enhancement and is rated for 0°C to +70°C operation.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar analog switch applications.

Compared with MAX321ESA+, the MAX321CUA+T trades thermal margin and temperature range for 65% smaller footprint-critical in handheld test gear. Versus ADG1411BRMZ, it delivers guaranteed NC operation and lower charge injection but mandates dual supplies, making it preferable for precision ±5V instrumentation where continuity and accuracy are non-negotiable.

Availability

MAX321CUA+T is available at Aetrix Electronics and suitable for battery-operated systems, ±5V DAC/ADC interfaces, and heads-up display signal routing requiring stable component supply and long-term obsolescence management.

Supply support for MAX321CUA+T 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 U.S.-based semiconductor company specializing in high-performance analog, mixed-signal, and power management ICs for industrial, communications, and consumer applications.

The MAX321CUA+T belongs to the MAX320/MAX321/MAX322 family of precision dual-supply SPST analog switches, engineered specifically for low-leakage, low-distortion signal routing in portable and military-grade instrumentation where NC default behavior and bipolar rail compatibility are essential.

FAQ

What is the default switch state of the MAX321CUA+T?

The MAX321CUA+T is a normally closed (NC) analog switch: both channels conduct by default when logic inputs IN1 and IN2 are low (≤2.5V). Applying a logic high (≥3.5V) opens each respective NC path. This fail-safe behavior ensures signal continuity during power-up, reset, or control signal loss-critical in safety-critical or battery-backed systems using the MAX321CUA+T.

Does the MAX321CUA+T support single-supply operation?

No, the MAX321CUA+T requires dual supplies (±3V to ±8V) and does not function with single-ended rails. Its internal circuitry relies on symmetric positive and negative references for proper logic threshold generation and analog signal handling across the full V− to V+ range. For single-supply alternatives, consult the MAX323/MAX324/MAX325 series-but note these lack the NC default and differ electrically from the MAX321CUA+T.

What is the maximum analog signal voltage range supported by the MAX321CUA+T?

The MAX321CUA+T supports analog signals from V− to V+, i.e., the full dual-supply range-for example, −5V to +5V with ±5V supplies. Input signals exceeding V+ or falling below V− are clamped by internal diodes; forward current must be limited to ≤30mA continuous or 100mA pulsed (1ms, 10% duty cycle). This rail-to-rail capability eliminates external level-shifting components in ±5V DAC/ADC interfaces using the MAX321CUA+T.

How does charge injection affect circuit performance with the MAX321CUA+T?

Charge injection in the MAX321CUA+T is guaranteed ≤5pC, causing a transient voltage glitch on hold capacitors during switching. In a 1000pF sample capacitor, this results in ≤5mV step error-acceptable for 12-bit accuracy (LSB = 2.44mV at 10V full-scale). Layout best practices (short traces, guard rings) and timing alignment (trigger sampling after t_OFF + settling) mitigate impact. This specification is rigorously validated and directly impacts precision in sample-and-hold circuits using the MAX321CUA+T.

Is the MAX321CUA+T pin-compatible with other variants in the MAX320/MAX321/MAX322 family?

Yes-the MAX321CUA+T shares identical pinout and package (µMAX-8) with MAX320CUA and MAX322CUA. All three have V+, IN1, COM2, NC2/NO2, V−, IN2, COM1, and NC1/NO1 arranged identically. However, logic behavior differs: MAX320CUA is NO, MAX321CUA+T is NC, and MAX322CUA combines one NO and one NC. Swapping requires verifying signal continuity requirements-not just physical fit-when replacing the MAX321CUA+T.