GND1

IN

ISO224

Clamp

Input

Signal

GND1

Input Voltage (V)

-20

-15

-10

-5

0

5

10

15

20

-50

-40

-30

-20

-10

0

10

20

30

40

50

D007

13

ISO224

www.ti.com

SBAS738 – JUNE 2018

Product Folder Links: ISO224

Submit Documentation Feedback

Copyright © 2018, Texas Instruments Incorporated

Feature Description (continued)

8.3.2 Input Clamp Protection Circuit

As illustrated in the Functional Block Diagram, the ISO224 features an internal clamp protection circuit on the

analog input IN. Using external protection circuits is recommended as a secondary protection scheme to protect

the device against surges, ESD events, and electrical fast transient (EFT) conditions.

Figure 6 shows a typical current versus voltage characteristic curve for the input clamp. Limit either the voltage

input current to the limits as defined in the Absolute Maximum Ratings table.

Figure 6. I-V Curve of the Input Clamp Protection Circuit

Figure 7 shows a simple method to limit the input current with an external series resistor that is also used as part

of the input low-pass filter.

Figure 7. Series Resistor-Based Input Current Limitation on the Analog Inputs of ISO224

The input overvoltage protection clamp on the ISO224 is intended to control transient excursions on the input

pins. Leaving the device in a state such that the clamp circuit is activated for extended periods of time in normal

or power-down mode is not recommended because this fault condition can degrade device performance and

reliability.