Datasheet

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INA138-Q1
INA138-Q1, INA168-Q1
www.ti.com SGLS174G –SEPTEMBER 2003–REVISED JANUARY 2013
Figure 9. Basic Circuit Connections
OUTPUT VOLTAGE RANGE
The output of the INA138-Q1 is a current, which is converted to a voltage by the load resistor, R
L
. The output
current remains accurate within the compliance voltage range of the output circuitry. The shunt voltage and the
input common-mode and power-supply voltages limit the maximum possible output swing. The maximum output
voltage compliance is limited by the lower of the two equations below:
V
out max
= (V
+
) − 0.7 V − (V
VIN+
− V
IN−
)
or
V
out max
= V
IN−
− 0.5 V
(whichever is lower)
BANDWIDTH
Measurement bandwidth is affected by the value of the load resistor, R
L
. High gain produced by high values of
R
L
yields a narrower measurement bandwidth (see the Typical Characteristics section). For widest possible
bandwidth, keep the capacitive load on the output to a minimum. Reduction in bandwidth due to capacitive load
is shown in the Typical Characteristics section.
If bandwidth limiting (filtering) is desired, a capacitor can be added to the output (see Figure 12). This does not
cause instability.
APPLICATIONS
The INA138-Q1 is designed for current-shunt measurement circuits, as shown in Figure 9, but its basic function
is useful in a wide range of circuitry. An engineer may find many unforeseen uses in measurement and level-
shifting circuits. A few ideas are illustrated in Figure 10 through Figure 15.
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