AMC3330: Sense Resistors Calculation

Simao Borges

Part Number: AMC3330
Other Parts Discussed in Thread: ISO224

Hello,

I'm using an AMC3330 Voltage Sensing, and when it comes to sensing resistors calculation and structure, spreadsheet (SBAR013 — Isolated Amplifier Voltage Sensing Excel Calculator) and datasheet page 24 and 25 don't give same architecture to connect sense resistors to AMC3330 and values are not the same.

In the datasheet 3 sensing resistors are used but in the spreadsheet it can be 2 or 3 but they are not connected the same way.

Can you clarify it ?

I would prefer to use only to resistors, is there any restrictions doing it ?

Best Regards,

Simao

1 month ago

0 Alexander Smith 1 month ago

TI__Guru 59612 points

Hi Simao,

Please see page 122 of this document: https://www.ti.com/lit/eb/slyy234/slyy234.pdf

0 Simao Borges 1 month ago

Prodigy 35 points

Hi Alexander,

Thank you very much for the document, it's very interesting.

It refers to an isolated amplifier with a dedicated supply for high voltage side (ISO224) on my PCB I can't do it, because of space lack, that's why I choose AMC3330, this one have an integrated high side power supply generated from low voltage side.

My concern is that sense resistors calculation differs between datasheet and spreadsheet.

Best Regards,

Simao

0 Alexander Smith 1 month ago in reply to Simao Borges

TI__Guru 59612 points

Hi Simao,

Maybe I misunderstand. Can you please clarify what you are not sure about?

The number of resistors in the resistive divider chain is determined by the individual resistor characteristics you select, as described in the document.

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AMC3330: Sense Resistors Calculation