INA210_08 Datasheet, PDF (8/17 Pages) Texas Instruments – Voltage Output, High or Low Side Measurement, Bi-Directional Zero-Drift Series CURRENT SHUNT MONITOR

INA210, INA211
INA212, INA213
INA214
SBOS437A – MAY 2008 – REVISED JUNE 2008............................................................................................................................................................... www.ti.com
APPLICATION INFORMATION
BASIC CONNECTIONS
Figure 23 shows the basic connections of the
INA210-INA214. The input pins, IN+ and IN–, should
be connected as closely as possible to the shunt
resistor to minimize any resistance in series with the
shunt resistance.
Reference
Voltage
Supply
R_SHUNT
Load
Alternatively, there are applications that must
measure current over a wide dynamic range that can
take advantage of the low offset on the low end of the
measurement. Most often, these applications can use
the lower gain INA213 or INA214 to accommodate
larger shunt drops on the upper end of the scale. For
instance, an INA213 operating on a 3.3V supply
could easily handle a full-scale shunt drop of 60mV,
with only 60µV of offset.
UNIDIRECTIONAL OPERATION
REF
GND
INA21x
OUT
R₁
R_{3 IN-}
Output
+2.7V to +26V
V+
C_BYPASS
0.01mF
to
0.1mF
IN+
R₂
R₄
Figure 23. Typical Application
Power-supply bypass capacitors are required for
stability. Applications with noisy or high impedance
power supplies may require additional decoupling
capacitors to reject power-supply noise. Connect
bypass capacitors close to the device pins.
POWER SUPPLY
The input circuitry of the INA210-INA214 can
accurately measure beyond its power-supply voltage,
V+. For example, the V+ power supply can be 5V,
whereas the load power supply voltage can be as
high as +26V. However, the output voltage range of
the OUT terminal is limited by the voltages on the
power-supply pin. Note also that the INA210-INA214
can withstand the full –0.3V to +26V in the input pins,
regardless of whether the device has power applied
or not.
Unidirectional operation allows the INA210-INA214 to
measure currents through a resistive shunt in one
direction. The most frequent case of unidirectional
operation sets the output at ground by connecting the
REF pin to ground. In unidirectional applications
where the highest possible accuracy is desirable at
very low inputs, bias the REF pin to a convenient
value above 50mV to get the device output swing into
the linear range for zero inputs.
A less frequent case of unipolar output biasing is to
bias the output by connecting the REF pin to the
supply; in this case, the quiescent output for zero
input is at quiescent supply. This configuration would
only respond to negative currents (inverted voltage
polarity at the device input).
BIDIRECTIONAL OPERATION
Bidirectional operation allows the INA210-INA214 to
measure currents through a resistive shunt in two
directions. In this case, the output can be set
anywhere within the limits of what the reference
inputs allow (that is, between 0V to V+). Typically, it
is set at half-scale for equal range in both directions.
In some cases, however, it is set at a voltage other
than half-scale when the bidirectional current is
nonsymmetrical.
The quiescent output voltage is set by applying
voltage to the reference input. Under zero differential
input conditions the output assumes the same voltage
as is applied to the reference input.
SELECTING R_S
The zero-drift offset performance of the
INA210-INA214 offers several benefits. Most often,
the primary advantage of the low offset characteristic
enables lower full-scale drops across the shunt. For
example, non-zero-drift current shunt monitors
typically require a full-scale range of 100mV.
The INA210-INA214 series gives equivalent accuracy
at a full-scale range on the order of 10mV. This
accuracy reduces shunt dissipation by an order of
magnitude with many additional benefits.
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