Analog Devices Inc. AD8218BRMZ

Overview

AD8218BRMZ from Analog Devices is a zero-drift, bidirectional current shunt monitor IC designed for high-side current sensing in 4 V to 80 V systems. It delivers 20 V/V fixed gain, ±50 µV typical input offset, ±100 nV/°C offset drift, and 110 dB CMRR at dc - enabling precision measurement of motor control, telecom power, and battery management currents across −40°C to +125°C.

For engineers reviewing the AD8218BRMZ datasheet, AD8218BRMZ pinout, AD8218BRMZ application, or AD8218BRMZ equivalent, key selection considerations include its buffered output interface with ADCs, internal 80 mV reference enablement via ENB pin, differential input range up to 250 mV, and MSOP-8 package compatibility with high-voltage PCB layout constraints.

Technical Context

The AD8218BRMZ implements a precision difference amplifier core with matched 1.5 MΩ/75 kΩ resistor network (0.01% matching), yielding exact 20 V/V gain. Its zero-drift architecture maintains ±100 nV/°C offset drift over full temperature and common-mode range.

It features an internal LDO allowing VS pin floating when powered from +IN (4 V–80 V), plus output clamping at 5.2 V to protect downstream ADCs. The ENB pin enables an 80 mV internal reference for unidirectional sensing, while REF pin accepts external low-impedance voltage for bidirectional offset setting (1 V/V gain).

Key Specifications

Pinout & Package

AD8218BRMZ is packaged in an 8-lead Mini Small Outline Package (MSOP, RM-8) with exposed pad connected to GND. Pin 6 is NC (no connect); exposed pad must be soldered to ground plane for thermal and electrical performance.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar current shunt monitor applications.

Compared with INA240A1QDRQ1 and MAX40056ATA+T, AD8218BRMZ uniquely integrates ENB-controlled 80 mV reference and REF pin programmability - enabling both optimized unidirectional dynamic range and flexible bidirectional offset without external components.

Availability

AD8218BRMZ is available at Aetrix Electronics and suitable for motor control, 48 V telecom power management, and battery management systems requiring stable component supply, long-term lifecycle support, and AEC-Q200-aligned thermal performance.

Supply support for AD8218BRMZ 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, headquartered in Norwood, MA.

The AD8218BRMZ belongs to Analog Devices' precision current sense amplifier product line, engineered specifically for high-voltage, high-accuracy bidirectional current monitoring in harsh thermal and electrical environments.

FAQ

What is the primary function of the AD8218BRMZ in a circuit?

The AD8218BRMZ functions as a zero-drift, high-voltage current shunt monitor that amplifies millivolt-level differential voltages across a shunt resistor with 20 V/V gain. It rejects common-mode voltages from 4 V to 80 V and delivers a buffered, ground-referenced output - making it ideal for high-side current sensing in motor control, telecom, and battery systems. Its design centers on precision, thermal stability, and integration of reference functionality.

How does the ENB pin affect the operation of the AD8218BRMZ?

Grounding the ENB pin (Pin 3) of the AD8218BRMZ enables its internal 80 mV reference, shifting the output baseline to 80 mV when differential input is zero. This extends usable dynamic range in unidirectional applications by avoiding ADC lower-rail saturation. Leaving ENB open or high disables the internal reference, allowing external voltage injection via the REF pin for bidirectional offset control - a key differentiator of the AD8218BRMZ.

Can the AD8218BRMZ operate without a separate power supply?

Yes, the AD8218BRMZ can operate without a separate power supply: its VS pin (Pin 2) may be left floating, allowing the device to draw power directly from the +IN input (4 V–80 V common-mode rail) via an internal LDO. This eliminates the need for an isolated 5 V supply in high-side sensing configurations. Alternatively, a 4 V–5.5 V standalone supply may be applied to VS for improved noise immunity in noisy bus environments.

What is the maximum differential input voltage the AD8218BRMZ can accurately measure?

The AD8218BRMZ accurately measures differential input voltages from 0 mV to 250 mV. Beyond this range, internal output clamping limits the output to ~5.2 V to protect downstream converters - meaning signals producing >250 mV across the shunt will saturate the output. This 250 mV limit corresponds to a full-scale shunt voltage compatible with standard 5 V ADCs and ensures linearity and specified gain accuracy.

Why does the AD8218BRMZ specify both ±50 µV typical offset and ±300 µV max over temperature?

The AD8218BRMZ specifies ±50 µV typical input offset voltage at 25°C and ±300 µV maximum over the full −40°C to +125°C range to reflect real-world thermal drift behavior. Its zero-drift architecture achieves ±100 nV/°C typical drift, resulting in bounded total offset excursion. Designers use the ±300 µV max value for worst-case error budgeting in safety-critical or high-precision applications - such as battery coulomb counting or motor torque control - where offset-induced gain errors must remain within specification.