AD8418 Current Sense Amplifier output voltage calculation

Hi Rob1234 ,

Good day. The initial gain @ 20 V/V is also the differential mode gain for a current sense amplifier. You can check out this article which could also give you additional ideas about current sense amplifiers: https://www.analog.com/media/en/technical-documentation/tech-articles/how-to-accurately-calculate-overcurrent-in-highside-currentsense-amplifiers.pdf.

Hope this helps. 

Regards,
Gilbeys

Thanks GLADION . 

Your Application Note 6329 is of use, although it does not perfectly match my application. It seems figure2 best describes the AD8418, with its specially trimmed internal resistors that create high CMRR.

I still find it strange that the AD8418 datasheet never states that Initial Gain = Differential mode gain. Is that fact obvious to the expert? 

If you have any other relevant application notes please let me know. I will Search for some myself. Especially of those concerning my exact amplifier.

Hi Rob1234 ,

Good day. Here are other relevant application notes for your reference:

https://www.analog.com/media/en/technical-documentation/application-notes/AN-1321.pdf

https://www.analog.com/media/en/technical-documentation/application-notes/AN-1318.pdf

https://www.analog.com/media/en/technical-documentation/application-notes/AN-1308.pdf

Also, here are some technical articles you might want to check,

https://www.analog.com/en/technical-articles/brushless-dc-motors-introduction-for-next-generation-missile-actuation-systems-outline.html

https://www.analog.com/en/technical-articles/differential-overvoltage-protection-circuits-for-current-sense-amplifiers.html

I think that it is important to remember that for a current sense amplifier, the gain being presented in the datasheet is the initial gain which equates to the differential gain. Hope this helps.

Regards,

Gilbeys