Datasheet

INA21x-Q1
V+
OUT
GND
IN-
IN+
C
BYPASS
Shutdown
Control
REF
Reference
Voltage
Supply
Load
R
SHUNT
Output
1 MΩ
R
PROTECT
10 Ω
R
PROTECT
10 Ω
R
3
1 MΩ R
4
Output
INA21x-Q1
Load
Supply
ADC
V+
OUT
GND
IN-
IN+
C
BYPASS
0.01 µF
to
0.1 µF
2.7 V to 26 V
REF
R
1
R
3
R
2
R
4
R
SHUNT
INA212-Q1, INA213A-Q1
INA214-Q1
www.ti.com SBOS475D –MARCH 2009–REVISED OCTOBER 2013
Figure 26. Sensing INA21x-Q1 to Cancel Effects of Impedance on the REF Input
USING THE INA21x-Q1 WITH COMMON-MODE TRANSIENTS ABOVE 26 V
With a small amount of additional circuitry, the INA21x-Q1 can be used in circuits subject to transients higher
than 26 V, such as automotive applications. Use only zener diode or zener-type transient absorbers (sometimes
referred to as Transzorbs) — any other type of transient absorber has an unacceptable time delay. Start by
adding a pair of resistors as shown in Figure 27 as a working impedance for the zener. It is desirable to keep
these resistors as small as possible, most often around 10 Ω. Larger values can be used with an effect on gain
that is discussed in the section on input filtering. Because this circuit is limiting only short-term transients, many
applications are satisfied with a 10-Ω resistor along with conventional zener diodes of the lowest power rating
that can be found. This combination uses the least amount of board space. These diodes can be found in
packages as small as SOT-523 or SOD-523.
Figure 27. INA21x-Q1 Transient Protection Using Dual Zener Diodes
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