VCM = 48V, VS = 5V, VREF = 2.5V, Adjustable Gain = 1

Figure 7-2. INA790B Total Error vs Input Current

7.1.2 Signal Filtering

Note that the integrated sensing element has inductance like all low-ohmic shunt resistors. Shunt inductance

can lead to shunt voltage overshoots and AC gain peaking, which is undesirable if system requires linear and

accurate current measurements when sensing small signal frequencies beyond 100kHz or when system can not

tolerate overshoot from fast current step responses such as when comparators are tracking for fast overcurrent

events. Figure 7-3 show INA790x shunt impedance vs frequency.

Frequency (Hz)

0.3

0.4

0.5

0.7

1

2

3

4

5

7

10

1

10

100

1k

10k

100k

1M

Figure 7-3. Shunt Impedance vs Frequency

Typically, inductance from low-Ohmic shunt resistors can be negated by adding a differential filter that creates

a pole to flatten zero introduced from inductance. For the INA790x an internal short is provided from Kelvin

sense connections to amplifier input to optimize noise, performance and quality. Thus, input resistance on these

connections is very low and to apply an input filter, a capacitance between IN+ and IN- that is greater than 22µF

is required. The filter capacitor must be placed as close as possible to IN+ and IN- pins. Figure 7-4 shows gain

response versus frequency with and without input filter capacitor.

INA790A, INA790B

SBOSAA6B – MAY 2024 – REVISED JULY 2025

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