INA193AIDBVRG4 Datasheet, PDF (9/24 Pages) Texas Instruments – CURRENT SHUNT MONITOR −16V to +80V Common-Mode Range

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Normal Case 2: V_SENSE ≥ 20mV, V_CM < V_S
This region of operation has slightly less accuracy
than Normal Case 1 as a result of the common-mode
operating area in which the part functions, as seen in
the Output Error vs Common-Mode Voltage curve
(Figure 6). As noted, for this graph V_S = 12V; for V_CM
< 12V, the Output Error increases as V_CM becomes
less than 12V, with a typical maximum error of
0.005% at the most negative V_CM = −16V.
Low V_SENSE Case 1:
V_SENSE < 20mV, −16V ≤ V_CM < 0;
and Low V_SENSE Case 3:
V_SENSE < 20mV, V_S < V_CM ≤ 80V
Although the INA193−INA198 family of devices are
not designed for accurate operation in either of these
regions, some applications are exposed to these
conditions; for example, when monitoring power
supplies that are switched on and off while V_S is still
applied to the INA193−INA198. It is important to know
what the behavior of the devices will be in these
regions.
As V_SENSE approaches 0mV, in these V_CM regions,
the device output accuracy degrades. A
larger-than-normal offset can appear at the current
shunt monitor output with a typical maximum value of
V_OUT = 300mV for V_SENSE = 0mV. As V_SENSE
approaches 20mV, V_OUT returns to the expected
output value with accuracy as specified in the
Electrical Characteristics. Figure 19 illustrates this
effect using the INA195 and INA198 (Gain = 100).
2.0
1.8
1.6
1.4
1.2
Actual
1.0
0.8
Ideal
0.6
0.4
0.2
0
0 2 4 6 8 10 12 14 16 18 20
V_SENSE (mV)
Figure 19. Example for Low V_SENSE Cases 1 and 3
(INA195, INA198: Gain = 100)
INA193, INA194
INA195, INA196
INA197, INA198
SBOS307F – MAY 2004 – REVISED FEBRUARY 2010
Low V_SENSE Case 2: V_SENSE < 20mV, 0V ≤ V_CM ≤ V_S
This region of operation is the least accurate for the
INA193−INA198 family. To achieve the wide input
common-mode voltage range, these devices use two
op amp front ends in parallel. One op amp front end
operates in the positive input common-mode voltage
range, and the other in the negative input region. For
this case, neither of these two internal amplifiers
dominates and overall loop gain is very low. Within
this region, V_OUT approaches voltages close to linear
operation levels for Normal Case 2. This deviation
from linear operation becomes greatest the closer
V_SENSE approaches 0V. Within this region, as V_SENSE
approaches 20mV, device operation is closer to that
described by Normal Case 2. Figure 20 illustrates this
behavior for the INA195. The V_OUT maximum peak for
this case is tested by maintaining a constant V_S,
setting V_SENSE = 0mV and sweeping V_CM from 0V to
V_S. The exact V_CM at which V_OUT peaks during this
test varies from part to part, but the V_OUT maximum
peak is tested to be less than the specified V_OUT
Tested Limit.
2.4
2.2 ^{INA195, INA198 V}OUT ^{Tested Limit(1)} _VCM1
2.0
1.8
V_CM2
1.6
Ideal
1.4
1.2
V_CM3
1.0
0.8 V_CM4
0.6
0.4
0.2
0
024
V_OUT tested limit at
V_SENSE = 0mV, 0 £ V_CM1 £ V_S.
V_CM2, V_CM3, and V_CM4 illustrate the variance
from part to part of the V_CM that can cause
maximum V_OUT with V_SENSE < 20mV.
6 8 10 12 14 16 18 20 22 24
V_SENSE (mV)
(1) INA193, INA196 V_OUT Tested Limit = 0.4V. INA194, INA197
V_OUT Tested Limit = 1V.
Figure 20. Example for Low V_SENSE Case 2
(INA195, INA198: Gain = 100)
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