RESET

ALERT

IN+

IN-

GND

CMPIN

CMPREF

10 k:

+

-

0 V to 26 V

+

-

G = 20, 50,

100, 200

R1

R2

5 V

2.7 V to 5.5 V

Load

INA381

Copyright © 2017, Texas Instruments Incorporated

< 10

< 10

VOUT

17

INA381

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SBOS848 – DECEMBER 2017

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Copyright © 2017, Texas Instruments Incorporated

Table 5 lists the external resistors required at the input of the CMPIN pin to set the hysteresis.

Table 5. Hysteresis Resistor Selection

HYSTERESIS VOLTAGE

EXTERNAL RESISTOR AT THE CMPIN PIN

50 mV

0 Ω

75 mV

6.25 kΩ

100 mV

12.5 kΩ

125 mV

18.75 kΩ

150 mV

25 kΩ

200 mV

37.5 kΩ

250 mV

50 kΩ

300 mV

62.5 kΩ

7.4.3 Using the INA381 With Common-Mode Transients Above 26 V

With a small amount of additional circuitry, the INA381 can be used in circuits subject to transients higher than

26 V. Use only Zener diodes 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 9 as a working impedance for the Zener diode. Keep these resistors as small as possible; most often

approximately 10

Ω. Larger values can be used with an effect on gain that is discussed in the Input Filtering

section. This circuit limits only short-term transients and, therefore, many applications are satisfied with a 10-

Ω

resistor along with conventional Zener diodes of the lowest acceptable power rating. 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 9. Transient Protection

In the event that low-power Zener diodes do not have sufficient transient absorption capability, a higher-power

transzorb must be used. Figure 9 shows that the most package-efficient solution involves using a single

transzorb and back-to-back diodes between the device inputs. The most space-efficient solutions are dual,

series-connected diodes in a single SOT-523 or SOD-523 package. In either of the examples provided in

Figure 9 and Figure 10, the total board area required by the INA381 with all protective components is less than

that of an SOIC-8 package, and only slightly greater than that of a VSSOP-8 package.