7.3.5 High-Side and Low-Side Current Sensing

The INAx191 supports input common-mode voltages from –0.2 V to +40 V. Because of the internal topology, the

applications, as shown in Figure 7-3.

Bus Suppl y

up to +40 V

High-Side Se nsing

Low-Side Se nsing

LOA D

is b us-voltage depen dent.

is a lwa ys n ear groun d a nd is

isolated fro m bus-voltage sp ikes.

IN+

IN±

IN+

IN±

Figure 7-3. High-Side and Low-Side Sensing Connections

7.3.6 High Common-Mode Rejection

The INAx191 uses a capacitively coupled amplifier on the front end. Therefore, dc common-mode voltages are

blocked from downstream circuits, resulting in very high common-mode rejection. Typically, the common-mode

rejection of the INAx191 is approximately 150 dB. The ability to reject changes in the DC common-mode voltage

allows the INAx191 to monitor both high- and low-voltage rail currents with very little change in the offset voltage.

7.3.7 Rail-to-Rail Output Swing

The INAx191 supports linear current-sensing operation with the output close to the supply rail and ground. The

GND is only GND + 1 mV with –10 mV of differential overdrive. For cases where the sense current is zero, the

swing to ground is determined by the zero current output specification. The value of the zero current output

voltage can differ from the specified value depending on the common-mode voltage, supply voltage, and output

load. The close-to-rail output swing maximizes the usable output range, particularly when operating the device

from a 1.8-V supply.

INA191, INA2191

SLYS020B – FEBRUARY 2019 – REVISED FEBRUARY 2021

www.ti.com

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