Gain Set by RL

Output Offset = (100 µA)(RL)

(independent of V+)

b) Using current source.

Gain Set by R1 || R2

a) Using resistor divider.

R1 + R2

Output Offset =

(VR)R2

R1

1

VR

INA138

3

4

VO

R2

REF200

100 µA

INA138

3

4

1

V+

VO

RL

14

INA138, INA168

SBOS122E – DECEMBER 1999 – REVISED DECEMBER 2017

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Copyright © 1999–2017, Texas Instruments Incorporated

Typical Applications (continued)

8.2.3 Offsetting the Output Voltage

For many applications using only a single power supply it may be required to level shift the output voltage away

from ground when there is no load current flowing in the shunt resistor. Level shifting the output of the INA1x8

devices is easily accomplished by one of two simple methods shown in Figure 14. The method on the left hand

side of Figure 14 illustrates a simple voltage divider method. This method is useful for applications that require

the output of the INA1x8 devices to remain centered with respect to the power supply at zero load current

through the shunt resistor. Using this method the gain is determine by the parallel combination of R1 and R2

while the output offset is determined by the voltage divider ratio R1 and R2. For applications that may require a

fixed value of output offset, independent of the power supply voltage, the current source method shown on the

right-hand side of Figure 14 is recommended. With this method a REF200 constant current source is used to

generate a constant output offset. Using his method the gain is determined by RL and the offset is determined by

the product of the value of the current source and RL.

Figure 14. Offsetting the Output Voltage