Datasheet

G=
V V-
OUT1 OUT2
100mV 20mV-
V RTI(Referred-To-Input)=
OS
V
OUT1
G
- 100mV
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
INA200
INA201
INA202
www.ti.com SBOS374C –NOVEMBER 2006–REVISED OCTOBER 2010
Normal Case 1: V
SENSE
≥ 20mV, V
CM
≥ V
S
larger-than-normal offset can appear at the current
shunt monitor output with a typical maximum value of
This region of operation provides the highest
V
OUT
= 300mV for V
SENSE
= 0mV. As V
SENSE
accuracy. Here, the input offset voltage is
approaches 20mV, V
OUT
returns to the expected
characterized and measured using a two-step
output value with accuracy as specified in the
method. First, the gain is determined by Equation 1.
Electrical Characteristics. Figure 27 illustrates this
effect using the INA202 (Gain = 100).
(1)
where:
V
OUT1
= Output Voltage with V
SENSE
= 100mV
V
OUT2
= Output Voltage with V
SENSE
= 20mV
Then the offset voltage is measured at V
SENSE
=
100mV and referred to the input (RTI) of the current
shunt monitor, as shown in Equation 2.
(2)
In the Typical Characteristics, the Output Error vs
Common-Mode Voltage curve (Figure 7) shows the
highest accuracy for the this region of operation. In
this plot, V
S
= 12V; for V
CM
≥ 12V, the output error is
Figure 27. Example for Low V
SENSE
Cases 1 and 3
at its minimum. This case is also used to create the
(INA202, Gain = 100)
V
SENSE
≥ 20mV output specifications in the Electrical
Characteristics table.
Low V
SENSE
Case 2: V
SENSE
< 20mV, 0V ≤ V
CM
≤ V
S
Normal Case 2: V
SENSE
≥ 20mV, V
CM
< V
S
This region of operation is the least accurate for the
This region of operation has slightly less accuracy
INA200 family. To achieve the wide input
than Normal Case 1 as a result of the common-mode
common-mode voltage range, these devices use two
operating area in which the part functions, as seen in
op amp front ends in parallel. One op amp front end
the Output Error vs Common-Mode Voltage curve
operates in the positive input common-mode voltage
(Figure 7). As noted, for this graph V
S
= 12V; for V
CM
range, and the other in the negative input region. For
< 12V, the Output Error increases as V
CM
becomes
this case, neither of these two internal amplifiers
less than 12V, with a typical maximum error of
dominates and overall loop gain is very low. Within
0.005% at the most negative V
CM
= –16V.
this region, V
OUT
approaches voltages close to linear
operation levels for Normal Case 2. This deviation
Low V
SENSE
Case 1:
from linear operation becomes greatest the closer
V
SENSE
< 20mV, –16V ≤ V
CM
< 0; and
V
SENSE
approaches 0V. Within this region, as V
SENSE
Low V
SENSE
Case 3:
approaches 20mV, device operation is closer to that
V
SENSE
< 20mV, V
S
< V
CM
≤ 80V
described by Normal Case 2. Figure 28 illustrates this
Although the INA200 family of devices are not
behavior for the INA202. The V
OUT
maximum peak for
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 INA200, INA201, or INA202, it is
peak is tested to be less than the specified V
OUT
important to know what the behavior of the devices
tested limit.
will be in these regions.
As V
SENSE
approaches 0mV, in these V
CM
regions,
the device output accuracy degrades. A
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