Data Sheet

LOAD
V
SUPPLY
f-3dB =
f
-3dB
1
2 (2R )Cp
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 +RW
FILT
´ 100
INA193 , INA194 , INA195
INA196 , INA197 , INA198
www.ti.com SBOS307G –MAY 2004–REVISED JANUARY 2015
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 R
FILT
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 k Ω), and the higher excursion of R
FILT
−
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 V
SENSE
and Common-Mode Voltage
The accuracy of the INA193−INA198 current shunt monitors is a function of two main variables: V
SENSE
(V
IN+
−
V
IN−
) and common-mode voltage, V
CM
, relative to the supply voltage, V
S
. V
CM
is expressed as (V
IN+
+ V
IN−
)/2;
however, in practice, V
CM
is seen as the voltage at V
IN+
because the voltage drop across V
SENSE
is usually small.
This section addresses the accuracy of these specific operating regions:
Normal Case 1: V
SENSE
≥ 20mV, V
CM
≥ V
S
Normal Case 2: V
SENSE
≥ 20mV, V
CM
< V
S
Low V
SENSE
Case 1: V
SENSE
< 20mV, −16V ≤ V
CM
< 0
Low V
SENSE
Case 2: V
SENSE
< 20mV, 0V ≤ V
CM
≤ V
S
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