INA191 datasheet(17/42 Pages) TI2

17 / 42 page

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 common-mode range is not restricted by the power-supply voltage (VS). The ability to operate with common-

mode voltages greater or less than VS allows the INAx191 to be used in high-side and low-side current-sensing

applications, as shown in Figure 7-3.

Bus Suppl y

up to +40 V

High-Side Se nsing

Low-Side Se nsing

LOA D

Commo n-mode volta ge (VCM)

is b us-voltage depen dent.

Commo n-mode volta ge (VCM)

is a lwa ys n ear groun d a nd is

isolated fro m bus-voltage sp ikes.

IN+

RSENS E

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. The common-mode rejection

of the INAx191 is 150 dB (typical). 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

maximum specified output swing to the positive rail is VS – 40 mV, and the maximum specified output swing

to 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.

www.ti.com

INA191, INA2191

SLYS020C – FEBRUARY 2019 – REVISED AUGUST 2021

Submit Document Feedback

Product Folder Links: INA191 INA2191

INA191 Scheda tecnica(PDF) 17 Page - Texas Instruments