Zero Drift, Bidirectional

Current Shunt Monitor

AD8218

Rev. A

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FEATURES

High common-mode voltage range

4 V to 80 V operating

−0.3 V to 85 V survival

Buffered output voltage

Gain = 20 V/V

Wide operating temperature range: −40°C to +125°C

Excellent ac and dc performance

±100 nV/°C typical offset drift

±50 µV typical offset

±5 ppm/°C typical gain drift

110 dB typical CMRR at dc

APPLICATIONS

High-side current sensing

48 V telecom

Power management

Base stations

Bidirectional motor control

Precision high voltage current sources

FUNCTIONAL BLOCK DIAGRAM

LDO

R2

R1

AD8218

R4

R3

+IN

–IN

OUT

ENB

REF

GND

Figure 1.

GENERAL DESCRIPTION

The AD8218 is a high voltage, high resolution current shunt

amplifier. It features a set gain of 20 V/V, with a maximum

±0.35% gain error over the entire temperature range. The

buffered output voltage directly interfaces with any typical

converter. The AD8218 offers excellent input common-mode

rejection from 4 V to 80 V. The AD8218 performs bidirectional

current measurements across a shunt resistor in a variety of

industrial and telecom applications, including motor control,

battery management, and base station power amplifier bias

control.

The AD8218 offers breakthrough performance throughout the

−40°C to +125°C temperature range. It features a zero-drift core,

which leads to a typical offset drift of ±100 nV/°C throughout

the operating temperature range and the common-mode voltage

range. Special attention is devoted to output linearity being

maintained throughout the input differential voltage range of

0 mV to ~250 mV. The AD8218 also includes an internal 80 mV

reference that can be enabled for optimal dynamic range in

unidirectional current sense applications. The typical input

offset voltage is ±50 µV.

The AD8218 is offered in an 8-lead MSOP package.