Datasheet

A2
R
L
INA193A
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>
INA193A-EP
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SBOS400A MAY 2007REVISED SEPTEMBER 2013
Shutdown
Because the INA193A consumes a quiescent current less than 1 mA, it 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-μF bypass capacitor, preferably ceramic with good high frequency characteristics.
This gate should have a supply voltage of 3 V or greater because the INA193A requires a minimum supply
greater than 2.7 V. In addition to eliminating quiescent current, this gate also turns off the 10 μA bias current
present at each of the inputs. An example shutdown circuit is shown in Figure 4.
Figure 4. INA193A Example Shutdown Circuit
Selecting R
S
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.
Transient Protection
The –16 V to 80 V common-mode range of the INA193A 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 INA193A is exposed to transients on the inputs in excess of its ratings,
then external transient absorption with semiconductor transient absorbers (zeners or Transzorbs) will be
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 will never allow the INA193A 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 INA193A– 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
INA193A inputs with two equal resistors on each input).
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