V

IN+

V

IN-

V

REF

GND

V

+

V

IN+

V

IN-

GND

V

+

Output

Output

Difference

Output

First Circuit

Second Circuit

Supply

Load

INA282, INA283

INA284, INA285

INA286

www.ti.com

SBOS485A – NOVEMBER 2009 – REVISED JULY 2010

CURRENT DIFFERENCING

Occasionally, the need arises to confirm that the current into a load is identical to the current out of a load,

usually as part of diagnostic testing or fault detection. This situation requires precision current differencing, which

is the same as summing except that the two amplifiers have the inputs connected opposite of each other. Under

normal operating conditions, the final output is very close to the reference value and proportional to any current

difference. Figure 41 is an example of the connections required for current differencing.

NOTE: This example is identical to the current summing example, except that the two shunt inputs are reversed in polarity,

this current differencing circuit is useful in detecting when current into and out of a load do not match.

Figure 41. Current Differencing Using an INA282 Family Device

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Product Folder Link(s): INA282 INA283 INA284 INA285 INA286