INA203A BURR-BROWN [Burr-Brown Corporation], INA203A Datasheet - Page 12

• Manufacturer Part Number: INA203A
• Description: Unidirectional Measurement Current-Shunt Monitor with Dual Comparators
• Manufacturer: BURR-BROWN [Burr-Brown Corporation]

INA203
INA204
INA205
SBOS393 – MARCH 2007
12
In the
Common-Mode Voltage curve
highest accuracy for this region of operation. In this
plot, V
its minimum. This case is also used to create the
V
Characteristics
Normal Case 2: V
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
< 12V, the Output Error increases as V
less than 12V, with a typical maximum error of
0.005% at the most negative V
Low V
V
Low
V
Although the INA203 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
applied to the INA203, INA204, or INA205. It is
important to know what the behavior of the devices
will be in these regions.
As V
the
larger-than-normal offset can appear at the current
shunt monitor output with a typical maximum value of
V
approaches 20mV, V
output value with accuracy as specified in the
Electrical
effect using the INA205 (Gain = 100).
Figure 31. Example for Low V
SENSE
SENSE
SENSE
OUT
SENSE
2.0
1.8
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
device
S
SENSE
= 300mV for V
0
Typical
< 20mV, V
7). As noted, for this graph V
0
V
= 12V; for V
< 20mV, –16V
20mV output specifications in the
SENSE
Characteristics.
approaches 0mV, in these V
2
Case 1:
table.
(INA205, Gain = 100)
Characteristics, the Output Error vs
output
4
S
SENSE
Actual
Case
< V
6
CM
OUT
CM
SENSE
V
8
SENSE
accuracy
12V, the output error is at
20mV, V
Figure 31
returns to the expected
3:
80V
10
V
(mV)
Ideal
CM
CM
(Figure
= 0mV. As V
SENSE
12
= –16V.
CM
< 0; and
14
S
Cases 1 and 3
< V
degrades.
= 12V; for V
illustrates this
7) shows the
CM
16
S
CM
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Electrical
becomes
18
regions,
S
is still
SENSE
20
CM
A
Low V
This region of operation is the least accurate for the
INA203
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
operation levels for Normal Case 2. This deviation
from linear operation becomes greatest the closer
V
approaches 20mV, device operation is closer to that
described by Normal Case 2.
this behavior for the INA205. The V
peak for this case is tested by maintaining a constant
V
0V to V
this test varies from part to part, but the V
maximum peak is tested to be less than the specified
V
SELECTING R
The value chosen for the shunt resistor, R
depends on the application and is a compromise
between
permissible voltage loss in the measurement line.
High values of R
lower currents by minimizing the effects of offset,
while low values of R
the
performance is attained with an R
provides a full-scale shunt voltage range of 50mV to
100mV.
measurements is (V
SENSE
S
OUT
NOTE: (1) INA203 V
, setting V
Figure 32. Example for Low V
2.4
2.2
2.0
1.8
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
Tested Limit.
0
supply
SENSE
0
approaches 0V. Within this region, as V
S
INA205 V
. The exact V
V
family.
CM4
2
Maximum
small-signal
Case 2: V
OUT
SENSE
4
OUT
line.
OUT
V
(INA205, Gain = 100)
CM3
SHUNT
Tested Limit
6
approaches voltages close to linear
V
from part to part of the V
maximum V
Tested Limit = 0.4V. INA204 V
V
SHUNT
CM2
To
CM2
= 0mV, and sweeping V
SHUNT
8
For
, V
CM
SHUNT
input
SENSE
V
CM3
10
SENSE
achieve
(1)
V
V
, and V
provide better accuracy at
at which V
accuracy
OUT
SENSE
OUT
– 0.25)/Gain.
12
most
(mV)
V
with V
Tested Limit at
minimize voltage loss in
< 20mV, 0V
CM1
= 0mV, 0
14
CM4
voltage
Figure 32
illustrate the variance
SENSE
16
CM
applications,
the
SENSE
£
OUT
that can cause
18
SHUNT
< 20mV.
V
and
OUT
CM1
OUT
for
20
peaks during
Tested Limit = 1V.
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Case 2
V
Ideal
22
value that
. S
V
maximum
maximum
illustrates
accurate
CM
CM
24
SHUNT
SENSE
input
from
best
V
OUT
S
,