High Voltage
Current Shunt Monitor
AD8212
Rev. B
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FEATURES
Adjustable gain
High common-mode voltage range
7 V to 65 V typical
7 V to >500 V with external pass transistor
Current output
Integrated 5 V series regulator
8-lead MSOP package
Operating temperature range of −40°C to +125°C
APPLICATIONS
Current shunt measurement
Motor controls
DC-to-DC converters
Power supplies
Battery monitoring
Remote sensing
FUNCTIONAL BLOCK DIAGRAM
AD8212
V+
I
OUT
COM BIAS ALPHA
SENSE
05942-001
OUTPUT
CURRENT
COMPENSATION
BIAS
CIRCUIT
8
6325
1
Figure 1.
GENERAL DESCRIPTION
The AD8212 is a high common-mode voltage, current shunt
monitor. It accurately amplifies a small differential input voltage
in the presence of large common-mode voltages up to 65 V
(>500 V with an external PNP transistor).
The AD8212 is ideal for current monitoring across a shunt
resistor in applications controlling loads, such as motors and
solenoids. The current output of the device is proportional to
the input differential voltage. The user can select an external
resistor to set the desired gain. The typical common-mode
voltage range of the AD8212 is 7 V to 65 V.
Another feature of the AD8212 is high voltage operation,
which is achieved by using an external high voltage breakdown
PNP transistor. In this configuration, the common-mode range
of the AD8212 is equal to the breakdown of the external PNP
transistor. Therefore, operation at several hundred volts is easily
achieved (see Figure 23).
The AD8212 features a patented output base current compensa-
tion circuit for high voltage operation mode. This ensures that
no base current is lost through the external transistor and
excellent output accuracy is maintained regardless of common-
mode voltage or temperature.
