The measurement error expected from the additional external filter resistors can be calculated using Equation 4,

where the gain error factor is calculated using Equation 5.

Gain Error (%) = 100

(100

Gain Error Factor)

-

´

(4)

The gain error factor, shown in Equation 4, can be calculated to determine the gain error introduced by the

additional external series resistance. Equation 4 calculates the deviation of the shunt voltage, resulting from

the attenuation and imbalance created by the added external filter resistance. Table 8-2 provides the gain error

factor and gain error for several resistor values.

Gain Error Factor =

RB × R1

(RB × R1) + (RB × RIN) + (2 × RIN × R1)

(5)

Where:

• RIN is the external filter resistance value.

• R1 is the INA293 input resistance value specified in Table 7-1.

• RB in the internal bias resistance, which is 6600 Ω ± 20%.

Table 8-2. Example Gain Error Factor and Gain Error for 10-Ω External Filter Input Resistors

DEVICE (GAIN)

GAIN ERROR FACTOR

GAIN ERROR (%)

INA293x1 (20)

0.997108386

-0.289161432

INA293x2 (50)

0.996512207

-0.348779273

INA293x3 (100)

0.996512207

-0.348779273

INA293x4 (200)

0.995520159

-0.447984072

INA293x5 (500)

0.992555831

-0.744416873

8.2 Typical Application

The INA293 is a unidirectional, current-sense amplifier capable of measuring currents through a resistive shunt

with shunt common-mode voltages from –4 V to +110 V.

GND

MCU

24 V

Solenoid

5 V

INA

R

SENSE

I

SENSE

ADC

Figure 8-2. Current Sensing in a Solenoid Application

8.2.1 Design Requirements

In this example application, the common-mode voltage ranges from 0 V to 24 V. The maximum sense current is

1.5 A, and a 5-V supply is available for the INA293. Following the design guidelines from the RSENSE and Device

Gain Selection section, a RSENSE of 50 mΩ and a gain of 50 V/V are selected to provide good output dynamic

range. Table 8-3 lists the design setup for this application.

Table 8-3. Design Parameters

DESIGN PARAMETERS

EXAMPLE VALUE

Power supply voltage

5 V

INA293

SBOS470B – DECEMBER 2019 – REVISED AUGUST 2022

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