INA290 datasheet(21/45 Pages) TI2

21 / 45 page

Use Equation 4 to calculate the measurement error expected from the additional external filter resistors, and use

Equation 5 to calculate the gain error factor.

Gain Error (%) = 100 x (Gain Error Factor í 1)

(4)

Gain Error Factor =

RB × R1

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

(5)

Where:

• RIN is the external filter resistance value.

• R1 is the INAx290 input resistance value specified in Table 7-1.

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

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.

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

DEVICE (GAIN)

GAIN ERROR FACTOR

GAIN ERROR (%)

A1 devices (20)

0.99658

–0.34185

A2 devices (50)

0.99598

–0.40141

A3 devices (100)

0.99598

–0.40141

A4 devices (200)

0.99499

–0.50051

A5 devices (500)

0.99203

–0.79663

8.2 Typical Application

The INAx290 is a unidirectional, current-sense amplifier capable of measuring currents through a resistive shunt

with shunt common-mode voltages from 2.7 V to 120 V. Figure 8-2 shows the circuit configuration for monitoring

current in a high-side radio frequency (RF) power amplifier (PA) application.

54 V

Out

DAC

GND

ADC

Microprocessor

INAx290

GND

Figure 8-2. Current Sensing in a PA Application (Single-Channel Device)

www.ti.com

INA290, INA2290, INA4290

SBOS961C – JUNE 2020 – REVISED JUNE 2021

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