Analog Devices Inc. AD8421BRMZ-RL

Overview

AD8421BRMZ-RL from Analog Devices is a low-power, ultra-low-noise instrumentation amplifier with 3.2 nV/√Hz input voltage noise, 2.3 mA quiescent current, and 10 MHz bandwidth at G = 1. It serves as a precision front-end signal conditioner for high-impedance sensors in medical instrumentation and vibration analysis systems.

For engineers reviewing the AD8421BRMZ-RL datasheet, AD8421BRMZ-RL pinout, AD8421BRMZ-RL application, or AD8421BRMZ-RL equivalent, this page delivers verified specifications, package mapping to 8-lead MSOP, gain-setting resistor interface details, and validated alternative options for low-noise, high-CMRR signal acquisition designs.

Technical Context

The AD8421BRMZ-RL employs a current-feedback architecture enabling 2 MHz bandwidth at G = 100 and 0.8 µs settling time to 0.001%, supporting high-channel-count multiplexed data acquisition. Its input stage features 30 GΩ||3 pF impedance and robust ±40 V input protection relative to opposite supply rail.

Gain is set by a single external resistor (G = 1 + 9.9 kΩ/R_G) across pins 2 and 3, while the REF pin provides precise output offset control. The device operates from ±2.5 V to ±18 V dual supply or 5 V to 36 V single supply, with specified performance from −40°C to +85°C.

Key Specifications

Pinout & Package

AD8421BRMZ-RL is housed in an 8-lead MSOP package (3 mm × 3 mm, 0.65 mm pitch) with exposed pad connected to −VS or left floating per layout guidelines.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar instrumentation amplifier applications.

Compared with AD8421BRMZ-RL, AD8420ARMZ trades 9 nV/√Hz more noise for 1.1 mA lower supply current, while LTC6915IMS8#PBF adds programmability at the cost of 5.3 nV/√Hz higher noise-making AD8421BRMZ-RL optimal for fixed-gain, ultra-low-noise sensor interfaces requiring minimal thermal load.

Availability

AD8421BRMZ-RL is available at Aetrix Electronics and suitable for medical instrumentation, precision data acquisition, and vibration analysis applications requiring stable component supply, long-term lifecycle support, and traceable sourcing.

Supply support for AD8421BRMZ-RL 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

Analog Devices is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, serving industrial, communications, automotive, and healthcare markets.

The AD8421 product line delivers precision instrumentation amplifiers optimized for extracting weak signals from noisy environments-designed specifically for medical diagnostics, structural health monitoring, and high-fidelity test equipment.

FAQ

What is the maximum gain achievable with AD8421BRMZ-RL?

The AD8421BRMZ-RL supports a gain range of 1 to 10,000, set by a single external resistor using the formula G = 1 + (9.9 kΩ/R_G). At G = 10,000, R_G = 0.99 Ω; stability and noise considerations require careful PCB layout and low-inductance resistor selection. The AD8421BRMZ-RL maintains usable bandwidth down to 0.2 MHz at G = 1000 and 200 kHz at G = 10,000.

Does AD8421BRMZ-RL support single-supply operation?

Yes, AD8421BRMZ-RL operates from a single supply of 5 V to 36 V. When used in single-supply mode, the reference pin (REF) must be biased to establish the output common-mode voltage-for example, to mid-supply for rail-to-rail compatible ADC interfacing. Input common-mode range extends from −V_S + 2.3 V to +V_S − 1.8 V, allowing direct connection of grounded sensors with appropriate REF setting.

How does the input overvoltage protection work on AD8421BRMZ-RL?

AD8421BRMZ-RL incorporates internal protection that allows input voltages up to 40 V beyond the opposite supply rail (e.g., +IN can tolerate −V_S + 40 V when −V_S = −15 V) without damage. This is achieved via integrated clamping structures that shunt excess current safely to the supplies. Unlike basic op amps, AD8421BRMZ-RL maintains functionality during transient overvoltage events typical in industrial sensor wiring.

What is the temperature range specification for AD8421BRMZ-RL?

AD8421BRMZ-RL is specified for operation from −40°C to +85°C, with guaranteed performance across this range for parameters including CMRR, offset drift, and gain error. The device remains functional up to +125°C, though certain parameters-such as input bias current and offset voltage-degrade outside the specified range. The BR grade variant ensures 94 dB minimum CMRR and 0.2 µV/°C max input offset drift within the −40°C to +85°C window.

Can AD8421BRMZ-RL drive capacitive loads directly?

AD8421BRMZ-RL is not unity-gain stable into purely capacitive loads and requires isolation resistance (typically 10–100 Ω) when driving >100 pF. For ADC input buffering, a series resistor between VOUT and the ADC's sampling capacitor prevents peaking and ensures monotonic settling. The AD8421BRMZ-RL's 35 V/µs slew rate and 0.6 µs settling time assume resistive loading per the datasheet test conditions (R_L = 2 kΩ); capacitive loading increases effective settling time and may induce oscillation without proper compensation.