The accuracy of any current-sense amplifier is maximized by choosing the current-sense resistor to be as large

as possible. A large sense resistor maximizes the differential input signal for a given amount of current flow

and reduces the error contribution of the offset voltage. However, there are practical limits as to how large the

current-sense resistor can be in a given application because of the resistor size and maximum allowable power

dissipation. Equation 2 gives the maximum value for the current-sense resistor for a given power dissipation

budget:

MAX

SENSE

2

MAX

PD

R

I

(2)

where:

An additional limitation on the size of the current-sense resistor and device gain is due to the power-supply

passed to the output, both positive and negative output swing limitations must be examined. Equation 3 provides

MAX

SENSE

SP

REF

I

R

GAIN < V

V

u

u

(3)

where:

• GAIN is the gain of the current-sense amplifier.

between the value of the sense resistor and the gain of the device under consideration. If the sense resistor

selected for the maximum power dissipation is too large, then it is possible to select a lower-gain device in order

to avoid positive swing limitations.

The negative swing limitation places a limit on how small the sense resistor value can be for a given application.

Equation 4 provides the limit on the minimum value of the sense resistor.

MIN

SENSE

SN

REF

I

R

GAIN > V

V

u

u

(4)

where:

• GAIN is the gain of the current-sense amplifier.

above GND to avoid negative swing limitations.

www.ti.com

INA190-EP

SBOSA74 – MAY 2022

Copyright © 2022 Texas Instruments Incorporated

Submit Document Feedback

21

Product Folder Links: INA190-EP