Datasheet

Shutdown
A2
R
L
INA193A INA198A-
OUT
R
S
A1
0.1 Fm
Load
V+
I
L
R
1
R
2
V
IN+
V
IN+
V
IN-
-16Vto80V
Negative
and
Positive
Common-Mode
Voltage
V+ 3V>
Selecting R
S
Transient Protection
INA193A-Q1 , INA194A-Q1 , INA195A-Q1
INA196A-Q1 , INA197A-Q1 , INA198A-Q1
www.ti.com ............................................................................................................................................... SBOS366C – AUGUST 2006 – REVISED OCTOBER 2008
Because the INA193A – INA198A consume a quiescent current less than 1 mA, they can be powered by either the
output of logic gates or by transistor switches to supply power. Use a totem pole output buffer or gate that can
provide sufficient drive along with 0.1 µ F bypass capacitor, preferably ceramic with good high frequency
characteristics. This gate should have a supply voltage of 3 V or greater because the INA193A – INA198A
requires a minimum supply greater than 2.7 V. In addition to eliminating quiescent current, this gate also turns off
the 10 µ A bias current present at each of the inputs. An example shutdown circuit is shown in Figure 4 .
Figure 4. INA193A – INA198A Example Shutdown Circuit
The value chosen for the shunt resistor, R
S
, depends on the application and is a compromise between
small-signal accuracy and maximum permissible voltage loss in the measurement line. High values of R
S
provide
better accuracy at lower currents by minimizing the effects of offset, while low values of R
S
minimize voltage loss
in the supply line. For most applications, best performance is attained with an R
S
value that provides a full-scale
shunt voltage range of 50 mV to 100 mV. Maximum input voltage for accurate measurements is 500 mV.
The – 16-V to +80-V common-mode range of the INA19xA is ideal for withstanding automotive fault conditions
ranging from 12 V battery reversal up to 80-V transients, since no additional protective components are needed
up to those levels. In the event that the INA19xA is exposed to transients on the inputs in excess of its ratings,
then external transient absorption with semiconductor transient absorbers (zeners or Transzorbs) are necessary.
Use of MOVs or VDRs is not recommended except when they are used in addition to a semiconductor transient
absorber. Select the transient absorber such that it never allows the INA19xA to be exposed to transients greater
than 80 V (that is, allow for transient absorber tolerance, as well as additional voltage due to transient absorber
dynamic impedance). Despite the use of internal zener-type ESD protection, the INA19xA does not lend itself to
using external resistors in series with the inputs since the internal gain resistors can vary up to ± 30%. (If gain
accuracy is not important, then resistors can be added in series with the INA19xA inputs with two equal resistors
on each input.)
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Product Folder Link(s): INA193A-Q1 INA194A-Q1 INA195A-Q1 INA196A-Q1 INA197A-Q1 INA198A-Q1