Anti-alias filter vs. voltage burden

Question

The FAQ doc for the AD4111/2/4/5 discusses the recommended values for the RC anti-alias filtering, but the fact that the resistors are in series with the internal burden resistor for current measurements means that 4-20 mA current loops will see 5 V of burden at 20 mA. This is a big chunk of the available headroom for our 12 V system. Are there alternative approaches? Obviously we can increase the C and reduce the R, but apparently this could have EMC implications? 
 Thanks, 
 Scott

JCCillion · Accepted Answer

Hi ScottB , 
 The value of the RC anti-alis filter is what we have tested the various EMC tests in the AN-1572 (Rev. 0) (analog.com) . Lower R values might be ok but we do not have any documents or test for other R values. 
 The resistor value is also relevant for other potential faults, for example accidentally shorting the input terminal to a +24V or -24V supply in the customer system. If the terminal shorted to -24V then this would result in high currents which may be beyond the specified abs max rating. 
 If the system design means that such faults cannot occur then the resistor value might not be as big a concern. However, the value would likely still have some influence on the ratings achieved in the EMC testing. 
 Regards, 
 JC)

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Anti-alias filter vs. voltage burden