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4-20mA current loop measurement protection

Veketti

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Dear All,

I’m wondering one design which uses 4-20mA current loop sensor which is supplied by battery powered unit stepped up by Recom RO-0524S 24V 1W step-up converter and in pcb 250ohm resistor to measure voltage across the loop by AD7992 12 bit ADC. According to the AD7992 datasheet its analog input has clamping diodes for ESD protection. This is the first time for me to deal with this kind of scenario, so I’m turning to you experts that do I need to add eg. BAT54S clamping diodes to the AD7992 input to further strengthen the ESD protection? What about capacitor for low pass filtering? I have read that the 4-20mA is very noise resistant due to its nature even in challenging industrial environments…

I’d assume that the sensors metal casing is tied to current loop ground or left floating, that static charge to the casing shouldn’t cause issues? Basically that’s the only point where static electricity can be conducted, everything else being plastic or rubber..

Thank you in advance
 

KlausST

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Hi,

Hard to help when we don't know about schematic, environment, voltages, capacitances...

Klaus
 

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