Datasheet

INA21x
V+
OUT
GND
IN-
IN+
PRODUCT R and R
3 4
INA210
INA211
INA212
INA213
INA214
5 kW
2 kW
1 kW
20 kW
10 kW
C
BYPASS
Shutdown
Control
REF
Reference
Voltage
1 MW
R
3
1 MW
R
4
Supply Load
R
SHUNT
Output
INA215 13.3 kW
INA210 , INA211 , INA212 , INA213 , INA214 , INA215
SBOS437F –MAY 2008–REVISED JUNE 2014 www.ti.com
8.4.2 Shutting Down the INA210-INA215 Series
While the INA210-INA215 series does not have a shutdown pin, its low power consumption allows powering from
the output of a logic gate or transistor switch that can turn on and turn off the INA210-INA215 power-supply
quiescent current.
However, in current shunt monitoring applications. there is also a concern for how much current is drained from
the shunt circuit in shutdown conditions. Evaluating this current drain involves considering the simplified
schematic of the INA210-INA215 in shutdown mode shown in Figure 25.
NOTE: 1-MΩ paths from shunt inputs to reference and INA21x outputs.
Figure 25. Basic Circuit for Shutting Down the INA210-INA215 with a Grounded Reference
Note that there is typically slightly more than 1-MΩ impedance (from the combination of 1-MΩ feedback and
5-kΩ input resistors) from each input of the INA210-INA215 to the OUT pin and to the REF pin. The amount of
current flowing through these pins depends on the respective ultimate connection. For example, if the REF pin is
grounded, the calculation of the effect of the 1-M Ω impedance from the shunt to ground is straightforward.
However, if the reference or op amp is powered while the INA210-INA215 is shut down, the calculation is direct;
instead of assuming 1 MΩ to ground, however, assume 1 MΩ to the reference voltage. If the reference or op
amp is also shut down, some knowledge of the reference or op amp output impedance under shutdown
conditions is required. For instance, if the reference source behaves as an open circuit when is not powered, little
or no current flows through the 1-MΩ path.
Regarding the 1-MΩ path to the output pin, the output stage of a disabled INA210-INA215 does constitute a
good path to ground; consequently, this current is directly proportional to a shunt common-mode voltage
impressed across a 1-MΩ resistor.
As a final note, when the device is powered up, there is an additional, nearly constant, and well-matched 25 μA
that flows in each of the inputs as long as the shunt common-mode voltage is 3 V or higher. Below 2-V common-
mode, the only current effects are the result of the 1-MΩ resistors.
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Product Folder Links: INA210 INA211 INA212 INA213 INA214 INA215