INA21x

V+

OUT

GND

IN-

IN+

PRODUCT

R and R

3

4

INA210

INA211

INA212

INA213

INA214

5kW

2kW

1kW

20kW

10kW

C

BYPASS

NOTE: 1M

paths from shunt inputs to reference and INA21x outputs.

W

Shutdown

Control

REF

Reference

Voltage

1MW

R

3

1MW

R

4

Supply

Load

R

SHUNT

Output

INA210, INA211

INA212, INA213

INA214

SBOS437E – MAY 2008 – REVISED JUNE 2013

www.ti.com

SHUTTING DOWN THE INA210-INA214 SERIES

While the INA210-INA214 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-INA214 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-INA214 in shutdown mode shown in Figure 25.

Figure 25. Basic Circuit for Shutting Down INA210-INA214 with Grounded Reference

Note that there is typically slightly more than 1M

Ω impedance (from the combination of 1MΩ feedback and 5kΩ

input resistors) from each input of the INA210-INA214 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 1M

Ω impedance from the shunt to ground is straightforward.

However, if the reference or op amp is powered while the INA210-INA214 is shut down, the calculation is direct;

instead of assuming 1M

Ω to ground, however, assume 1MΩ 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 it is unpowered, little or no

current flows through the 1M

Ω path.

Regarding the 1M

Ω path to the output pin, the output stage of a disabled INA210-INA214 does constitute a good

path to ground; consequently, this current is directly proportional to a shunt common-mode voltage impressed

across a 1M

Ω 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 3V or higher. Below 2V common-

mode, the only current effects are the result of the 1M

Ω resistors.

12

Submit Documentation Feedback

Copyright © 2008–2013, Texas Instruments Incorporated

Product Folder Links: INA210 INA211 INA212 INA213 INA214