Frequency (Hz)

10

20

30

40

50

70

100

200

300

400

500

1

10

100

1k

10k

100k

1M

Adjustable Gain = 1

Adjustable Gain = 1 with 22uF Input Capacitor

Figure 7-4. INA790x Gain vs Frequency Before and After Adding 22µF Input Capacitor

Another option to negate the shunt inductance is to introduce the zero in transfer function at the adjustable

gain-setting output buffer with a circuit configuration referred to as a RISO Dual Feedback. This operational

amplifier network provides a zero to cancel out shunt inductance without sacrificing overall bandwidth nor output

impedance. Figure 7-5 shows RISO Dual Feedback circuit configuration

PWM

Rejection

Shunt

Resistor

OUT

FB

REF

VS

GND

IS+

IS-

2.7V to 5.5V

+

–

EXT REF

Shunt Current

Alert

LOAD

GND

Rpullup

RFB1

RFB2

+

–

0.1 F

RISO

IN-

IN+

CF

CL

Figure 7-5. INA790x With RISO-Dual-Feedback

Based upon measured bandwidth and output impedance, Table 7-4 shows values for circuit components that

can be used to achieve the circuit with the desired gain. Resistor tolerances under 2% is recommended.

Figure 7-6 and Figure 7-7 show the load step responses with and without RISO Dual Feedback circuit with the

component values in Table 7-4.

Table 7-4. INA790x RISO Dual Feedback Values

Adjustable Gain

Total Gain (mV/A)

RFB1

RFB2

RISO

CF

Min CL

1

20

19.1kΩ

Open

200Ω

10nF

10nF

2

40

19.1kΩ

19.1kΩ

0Ω (Short)

0.1nF

Open

3

60

19.1kΩ

9.76kΩ

0Ω (Short)

0.1nF

Open

4

80

19.1kΩ

6.26kΩ

0Ω (Short)

0.1nF

Open

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INA790A, INA790B

SBOSAA6B – MAY 2024 – REVISED JULY 2025

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