LOAD

V

SUPPLY

f-3dB =

f

-

3dB

1

2 (2R

)C

p

FILT

FILT

C

FILT

R

<< R

SHUNT

FILTER

R

<100W

FILT

R

<100W

FILT

VIN+

VIN-

+5V

V+

OUT

INA193-INA198

R

1

5kW

R

L

R

1

5kW

GainError%=100 -

5kW

5k

+R

W

FILT

´ 100

17

INA193, INA194, INA195

INA196, INA197, INA198

www.ti.com

SBOS307G – MAY 2004 – REVISED JANUARY 2015

Product Folder Links: INA193 INA194 INA195 INA196 INA197 INA198

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Copyright © 2004–2015, Texas Instruments Incorporated

Device Functional Modes (continued)

(1)

Total effect on gain error can be calculated by replacing the 5-kΩ term with 5 kΩ − 30%, (or 3.5 kΩ) or 5 kΩ +

30% (or 6.5 kΩ). The tolerance extremes of RFILT can also be inserted into the equation. If a pair of 100-Ω 1%

resistors are used on the inputs, the initial gain error will be approximately 2%. Worst-case tolerance conditions

will always occur at the lower excursion of the internal 5-kΩ resistor (3.5 kΩ), and the higher excursion of RFILT −

3% in this case.

Note that the specified accuracy of the INA193-INA198 devices must then be combined in addition to these

tolerances. While this discussion treated accuracy worst-case conditions by combining the extremes of the

resistor values, it is appropriate to use geometric mean or root sum square calculations to total the effects of

accuracy variations.

Figure 25. Input Filter (Gain Error

− 1.5% To −2.2%)

8.4.2 Accuracy Variations as a Result of VSENSE and Common-Mode Voltage

The accuracy of the INA193

−INA198 current shunt monitors is a function of two main variables: VSENSE (VIN+ −

VIN−) and common-mode voltage, VCM, relative to the supply voltage, VS. VCM is expressed as (VIN+ + VIN−)/2;

however, in practice, VCM is seen as the voltage at VIN+ because the voltage drop across VSENSE is usually small.

This section addresses the accuracy of these specific operating regions:

Normal Case 1: VSENSE ≥ 20mV, VCM ≥ VS

Normal Case 2: VSENSE ≥ 20mV, VCM < VS

Low VSENSE Case 1: VSENSE < 20mV, −16V ≤ VCM < 0

Low VSENSE Case 2: VSENSE < 20mV, 0V ≤ VCM ≤ VS