Datasheet

2.4
2.2
2.0
1.8
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0
0
2
4 6 8
10 12 14 16 18 20 22
V (V)
OUT
V (mV)
SENSE
24
INA195,INA198V TestedLimit
OUT
(1)
V
CM2
V
CM3
V
CM4
V ,V ,andV
CM2 CM3 CM4
illustratethevariance
fromparttopartoftheV thatcancause
CM
maximumV
OUT SENSE
withV <20mV.
V testedlimitat
OUT
V =0mV,0 V£
SENSE CM1 S
V£ .
Ideal
VCM1
2.0
1.8
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0
0
2
4 6 8
10 12 14 16 18
V (V)
OUT
V (mV)
SENSE
20
Actual
Ideal
INA193, INA194
INA195, INA196
INA197, INA198
www.ti.com SBOS307F –MAY 2004–REVISED FEBRUARY 2010
Normal Case 2: V
SENSE
≥ 20mV, V
CM
< V
S
Low V
SENSE
Case 2: V
SENSE
< 20mV, 0V ≤ V
CM
≤ V
S
This region of operation has slightly less accuracy This region of operation is the least accurate for the
than Normal Case 1 as a result of the common-mode INA193−INA198 family. To achieve the wide input
operating area in which the part functions, as seen in common-mode voltage range, these devices use two
the Output Error vs Common-Mode Voltage curve op amp front ends in parallel. One op amp front end
(Figure 6). As noted, for this graph V
S
= 12V; for V
CM
operates in the positive input common-mode voltage
< 12V, the Output Error increases as V
CM
becomes range, and the other in the negative input region. For
less than 12V, with a typical maximum error of this case, neither of these two internal amplifiers
0.005% at the most negative V
CM
= −16V. dominates and overall loop gain is very low. Within
this region, V
OUT
approaches voltages close to linear
Low V
SENSE
Case 1: operation levels for Normal Case 2. This deviation
V
SENSE
< 20mV, −16V ≤ V
CM
< 0;
from linear operation becomes greatest the closer
and Low V
SENSE
Case 3:
V
SENSE
approaches 0V. Within this region, as V
SENSE
V
SENSE
< 20mV, V
S
< V
CM
≤ 80V
approaches 20mV, device operation is closer to that
described by Normal Case 2. Figure 20 illustrates this
Although the INA193−INA198 family of devices are
behavior for the INA195. The V
OUT
maximum peak for
not designed for accurate operation in either of these
this case is tested by maintaining a constant V
S
,
regions, some applications are exposed to these
setting V
SENSE
= 0mV and sweeping V
CM
from 0V to
conditions; for example, when monitoring power
V
S
. The exact V
CM
at which V
OUT
peaks during this
supplies that are switched on and off while V
S
is still
test varies from part to part, but the V
OUT
maximum
applied to the INA193−INA198. It is important to know
peak is tested to be less than the specified V
OUT
what the behavior of the devices will be in these
Tested Limit.
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).
(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)
Figure 19. Example for Low V
SENSE
Cases 1 and 3
(INA195, INA198: Gain = 100)
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