AMC0x11R Inverting Input

Support Q&A
1

Hi all,

I’m looking at using one of the AMC0x11R isolated amplifiers and am wondering if the SNSN input can be used as an inverting input by tying INP to GND1. The datasheet lists the SNSN pin as an “analog input” and “GND1 sense pin and inverting analog input to the amplifier. Connect to GND1.” Does that mean that I can use it as an inverting input, or must I tie it to GND1 to act as a reference? There are no typical apps or further information on this in the datasheet. Thanks for the help.

2

Hello collwentzi,
Welcome to the TechForum, you give no part number, but I was able to pull the datasheet off the TI website. The link is to the TI engineering forum, and they would be more able to assist you with the information requested.
TI E2E support forums

3

The input signal to the device is defined as the difference between VINP
and VSNSN, and one of the basic ground rules of analog electronics is that the field of play is delimited by the power supply potentials.

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Since the output has no negative supply potential, the output can’t swing negative relative to its reference point. The abs max table allows both pins to go as far as 3v below ground on the input so it’s conceivable that the output may still respond to a positive input signal (VINP -VSNSN >0) when VINP=0, but it’s not the sort of thing one should count on.

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The better understanding of the SNSN pin being called in “inverting input” is that the output signal responds in an anti-proportional manner to signals presented to it; an increase in potential applied to the SNSN pin results an a decrease in potential at the OUT pin.