Datasheet

G=
V V
OUT1 OUT2
-
100mV 20mV-
R
S
Load
V
IN+
-16Vto+80V
I
S
V
IN+
V
IN-
+2.7Vto+18V
V+
OUT
INA193-INA198
R
1
R
L
R
2
V RTI(Referred-To-Input)=
OS
V
OUT1
G
- 100mV
INA193, INA194
INA195, INA196
INA197, INA198
SBOS307F –MAY 2004–REVISED FEBRUARY 2010 www.ti.com
APPLICATIONS INFORMATION
BASIC CONNECTION ACCURACY VARIATIONS AS A RESULT OF
V
SENSE
AND COMMON-MODE VOLTAGE
Figure 18 shows the basic connection of the
INA193-INA198. The input pins, V
IN+
and V
IN−
, should The accuracy of the INA193−INA198 current shunt
be connected as closely as possible to the shunt monitors is a function of two main variables: V
SENSE
resistor to minimize any resistance in series with the (V
IN+
− V
IN−
) and common-mode voltage, V
CM
, relative
shunt resistance. 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
Power-supply bypass capacitors are required for
voltage at V
IN+
because the voltage drop across
stability. Applications with noisy or high impedance
V
SENSE
is usually small.
power supplies may require additional decoupling
capacitors to reject power-supply noise. Connect This section addresses the accuracy of these specific
bypass capacitors close to the device pins. 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
Low V
SENSE
Case 3: V
SENSE
< 20mV, V
S
< V
CM
≤
80V
Normal Case 1: V
SENSE
≥ 20mV, V
CM
≥ V
S
This region of operation provides the highest
accuracy. Here, the input offset voltage is
characterized and measured using a two-step
method. First, the gain is determined by Equation 1.
where:
V
OUT1
= Output Voltage with V
SENSE
= 100mV
V
OUT2
= Output Voltage with V
SENSE
= 20mV (1)
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.
Figure 18. INA193-INA198 Basic Connection
(2)
In the Typical Characteristics, the Output Error vs
POWER SUPPLY
Common-Mode Voltage curve (Figure 6) shows the
highest accuracy for this region of operation. In this
The input circuitry of the INA193-INA198 can
plot, V
S
= 12V; for V
CM
≥ 12V, the output error is at its
accurately measure beyond its power-supply voltage,
minimum. This case is also used to create the V
SENSE
V+. For example, the V+ power supply can be 5V,
≥ 20mV output specifications in the Electrical
whereas the load power-supply voltage is up to +80V.
Characteristics table.
The output voltage range of the OUT terminal,
however, is limited by the voltages on the
power-supply pin.
8 Submit Documentation Feedback Copyright © 2004–2010, Texas Instruments Incorporated
Product Folder Link(s): INA193 INA194 INA195 INA196 INA197 INA198