Zero Drift, Bidirectional
Current Shunt Monitor
AD8218
FUNCTIONAL BLOCK DIAGRAM
FEATURES
V
S
High common-mode voltage range
4 V to 80 V operating
R4
AD8218
−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
R1
–IN
+IN
OUT
R2
R3
LDO
ENB
GND
REF
5 ppm/°C typical gain drift
110 dB typical CMRR at dc
Figure 1.
APPLICATIONS
High-side current sensing
48 V telecom
Power management
Base stations
Bidirectional motor control
Precision high voltage current sources
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 µ V.
The AD8218 is offered in an 8-lead MSOP package.
Rev. A
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