Datasheet

INA21x-Q1
V+
OUT
GND
IN-
IN+
C
BYPASS
0.01 µF
to
0.1 µF
2.7 V to 26 V
REF
Reference
Voltage
Supply Load
R
SHUNT
Output
R
1
R
3
R
2
R
4
INA212-Q1, INA213A-Q1
INA214-Q1
SBOS475D –MARCH 2009–REVISED OCTOBER 2013 www.ti.com
APPLICATION INFORMATION
BASIC CONNECTIONS
Figure 23 shows the basic connections of the INA212-Q1, INA213A-Q1 or INA214-Q1. 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.
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 INA21x-Q1 can accurately measure beyond its power-supply voltage, V+. For example,
the V+ power supply can be 5 V, whereas the load power supply voltage can be as high as 26 V. However, the
output voltage range of the OUT terminal is limited by the voltages on the power-supply pin. Note also that the
INA21x-Q1 can withstand the full –0.3 V to 26 V in the input pins, regardless of whether the device has power
applied or not.
SELECTING R
S
The zero-drift offset performance of the INA21x-Q1 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 100 mV.
The INA21x-Q1 gives equivalent accuracy at a full-scale range on the order of 10 mV. This accuracy reduces
shunt dissipation by an order of magnitude with many additional benefits.
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 INA212-Q1, INA213A-Q1 or INA214-Q1 to accommodate larger shunt drops on the upper end of the scale.
For instance, an INA213A-Q1 operating on a 3.3-V supply could easily handle a full-scale shunt drop of 60 mV,
with only 60 µV of offset.
UNIDIRECTIONAL OPERATION
Unidirectional operation allows the INA21x-Q1 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 50 mV to get the device output swing into the linear range for zero inputs.
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Product Folder Links: INA212-Q1 INA213A-Q1 INA214-Q1