1.7 V to 5.5 V

IN±

IN+

VS

OUT

+

±

Bus Voltage

up to 40 V

Load

Capacitively

Coupled

Amplifier

INA186

REF

GND

< 1 k:

< 1 k:

Transorb

0.1 µF

1.7 V to 5.5 V

IN±

IN+

VS

OUT

+

±

Bus Voltage

up to 40 V

Load

Capacitively

Coupled

Amplifier

INA186

REF

GND

< 1 k:

< 1 k:

0.1 µF

21

INA186

www.ti.com

SBOS318A – APRIL 2019 – REVISED NOVEMBER 2019

Product Folder Links: INA186

Submit Documentation Feedback

Copyright © 2019, Texas Instruments Incorporated

Application Information (continued)

8.1.4 Common-Mode Voltage Transients

With a small amount of additional circuitry, the INA186 can be used in circuits subject to transients that exceed

the absolute maximum voltage ratings. The most simple way to protect the inputs from negative transients is to

add resistors in series with the IN– and IN+ pins. Use resistors that are 1 kΩ or less, and limit the current in the

ESD structures to less than 5 mA. For example, using 1-kΩ resistors in series with the INA186 allows voltages

as low as –5 V, while limiting the ESD current to less than 5 mA. If protection from high-voltage or more-

negative, common-voltage transients is needed, use the circuits shown in Figure 33 and Figure 34. When

implementing these circuits, 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 a working impedance for the Zener diode, as shown in Figure 33. Keep these resistors as small as

possible; most often, use around 100

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

Signal Conditioning section. This circuit limits only short-term transients; therefore, many applications are

satisfied with a 100-

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 33. Transient Protection Using Dual Zener Diodes

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

transzorb must be used. The most package-efficient solution involves using a single transzorb and back-to-back

diodes between the device inputs, as shown in Figure 34. The most space-efficient solutions are dual, series-

connected diodes in a single SOT-523 or SOD-523 package. In either of the examples shown in Figure 33 and

Figure 34, the total board area required by the INA186 with all protective components is less than that of an SO-

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

Figure 34. Transient Protection Using a Single Transzorb and Input Clamps

For more information, see the Current Shunt Monitor With Transient Robustness reference design.