Analog Devices Inc./Maxim Integrated MAX321CUA

Overview

MAX321CUA from Maxim Integrated is a precision dual-channel, normally closed (NC) SPST analog switch operating from ±3V to ±8V dual supplies. It delivers 35Ω max on-resistance, <2Ω channel-to-channel R_ON matching, and <4Ω R_ON flatness at ±5V, with 150ns max turn-on time and 100pA max leakage at +25°C - ideal for ±5V DAC/ADC signal routing in battery-powered test equipment.

For engineers reviewing the MAX321CUA datasheet, MAX321CUA pinout, MAX321CUA application, or MAX321CUA equivalent, key selection criteria include bipolar supply compatibility, guaranteed NC logic behavior, low charge injection (<5pC), ESD robustness (>2000V), and µMAX-8 package suitability for space-constrained analog front-ends.

Technical Context

The MAX321CUA implements complementary MOSFET pairs per channel with matched threshold voltages to achieve <2Ω R_ON matching and <4Ω R_ON flatness over ±3V to ±8V supplies. Its NC configuration ensures default conduction when logic input is low (IN = 0V or V−), with break-before-make timing not applicable (exclusive to MAX322).

Charge injection is minimized via balanced gate drive and layout symmetry, yielding ≤5pC across the full analog range (V− to V+). Input logic thresholds scale with V+: VIH ≈ V+ − 1.5V, VIL ≈ V+ − 2.5V - enabling direct interface with ±5V CMOS logic without level shifting.

Key Specifications

Pinout & Package

MAX321CUA is housed in an 8-pin µMAX package (2.1mm × 1.6mm, 0.5mm pitch), specified for 0°C to +70°C operation. The package features exposed pad for thermal enhancement and is RoHS-compliant.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX321ESA, the MAX321CUA trades industrial temperature range for 40% smaller PCB area; versus ADG1412BRUZ, it provides true hardware-enforced NC behavior and lower leakage, but requires dual supplies - making MAX321CUA optimal for compact, battery-powered, fail-safe analog routing.

Availability

MAX321CUA is available at Aetrix Electronics and suitable for battery-operated test equipment, ±5V precision data acquisition systems, and military radio signal routing requiring stable component supply and long-term obsolescence management.

Supply support for MAX321CUA 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, communications, and aerospace applications.

The MAX320/MAX321/MAX322 family was engineered specifically for high-fidelity, low-leakage analog switching in dual-supply systems where NC default behavior, rail-to-rail signal handling, and minimal charge injection are essential.

FAQ

What is the default state of the switches in MAX321CUA?

The MAX321CUA contains two normally closed (NC) analog switches. When logic inputs IN1 and IN2 are low (≤V+ − 2.5V), both NC1 and NC2 conduct between their respective COM and NC terminals. This default-closed behavior ensures signal continuity during power-up, reset, or logic failure - a key safety feature in guidance and control systems where uninterrupted analog monitoring is required. The MAX321CUA does not implement break-before-make timing.

Can MAX321CUA operate from a single supply?

No, the MAX321CUA requires dual supplies: V+ must be ≥+3V and V− must be ≤−3V, with |V+ − V−| ≤17V. It is not rated for single-supply operation. For single-supply alternatives, refer to the MAX323/MAX324/MAX325 family. Attempting to tie V− to ground or use asymmetric supplies outside the ±3V to ±8V range risks exceeding absolute maximum ratings and may cause permanent damage or unpredictable switching behavior in the MAX321CUA.

What is the maximum analog signal range supported by MAX321CUA?

The MAX321CUA supports analog signals from V− to V+, i.e., rail-to-rail operation. With ±5V supplies, it reliably switches signals from −5V to +5V. Internal clamping diodes limit any pin voltage to (V− − 0.3V) to (V+ + 0.3V); exceeding this range risks forward-biasing protection diodes and injecting current into supplies. For overvoltage tolerance beyond ±8.5V (e.g., ±12V fault conditions), external blocking diodes as shown in Figure 1 of the MAX321CUA datasheet are required.

How does temperature affect leakage current in MAX321CUA?

At +25°C, MAX321CUA guarantees ≤100pA off-leakage and ≤2.5nA on-leakage. Leakage increases with temperature: typical off-leakage rises to ~10nA at +85°C and ~100nA at +125°C (though MAX321CUA is only rated to +70°C). On-leakage remains below 2.5nA up to +85°C per characterization data. These values are confirmed by 100% testing at maximum hot temperature and correlated at room temperature - ensuring predictable performance in battery-powered instruments operating across commercial temperature ranges.

Is MAX321CUA pin-compatible with other packages in the MAX321 family?

Yes, the MAX321CUA shares identical pinout and electrical functionality with MAX321CPA (PDIP), MAX321CSA (SO), and MAX321ESA (SO, extended temp). All variants use the same 8-pin configuration: V+, IN1, COM2, NC2, V−, IN2, COM1, NC1. However, thermal and mechanical characteristics differ - the µMAX package offers superior power density and smaller footprint but requires careful PCB layout for thermal relief and solder paste volume control during reflow.