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MAX22196 Recommended for New Designs
The MAX22196 is an industrial octal digital input that translates eight industrial 24V or TTL level inputs to logic level outputs. The device has a serial...
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MAX22196 on Analog.com

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Input protection against load dump overvoltage

JMarty

on Jul 25, 2024

Category: Hardware

Product Number: MAX22196

How is possible to protect MAX22196 INx inputs against load dump 60V overvoltage (like ISO 13766-1 pulse 5b)? It's recommended to put 680Ohms input resistor but for transient like ESD pulse. There is no information about max input current for INx inputs neither equivalent diagram.

Thank you for your help.

Tags: hardware 60v load dump MAX22196 overvoltage Industrial I/O digital i/o Show More

0 EZAutoReply

on Jul 25, 2024 1:10 PM
The inputs are current limited so there is no "max" input current instead you should prevent the voltage from exceeding the absolute maximum rating. A series surge resistor to drop the voltage (Rsurge * Isurge) or a sufficient TVS diode to clamp any voltages above it's forward voltage threshold on the inputs will protect the channels from being damaged by surge/load dump events. A 680Ohm or SMAJ33CA was used in our tests and were found to meet IEC 61000-4-5 standards.
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0 JMarty
on Jul 26, 2024 12:11 PM in reply to EZAutoReply
Hi BenRed

Thanks for your reply!

However, I'm concerned not by ESD but more by load dump transient (60V/300ms). Front TVS will not support this overvoltage. I'm thinking about put TVS after pulse resitor and directly on INx input side. What do you think?
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Input protection against load dump overvoltage