LTC1967 RMS-DC Converter transformer issue

[aomepsan]

Hi everyone,

I'm trying to read RMS voltage with LTC1967.
I have seen this post before "https://www.electro-tech-online.com/threads/ltc1966-rms-dc-converter-issue.158100/" and clearly understand circuit.
My question is that do I have to use a transformer? because I don't have big area to put it.

Thanks for reply
Wish you all the best

 

[rjenkinsgb]

What voltage range from what source?

If it's from AC mains, you need a transformer for safety isolation, if anything else at all will be connected to the circuit.

 

[aomepsan]

Unfortunately AC mains and dimmed 10-60VAC. If we push isolation into the background, isn't there other way to do that?

 

[rjenkinsgb]

If it's connected to other things, it must have isolation. If it's going to be a self-contained and fully insulated instrument, get it working using a low voltage AC source to start with then change the input scaling resistors to suit the final voltage range.

Isolation without a mains transformer can be done using isolation anps and a miniature DC-DC converter to run them.
eg

https://docs.rs-online.com/4296/0900766b8130f7ae.pdf

And something like this to power the input stage:

RFM-0505S | Recom RFM DC-DC Converter, 5V dc/ 200mA Output, 4.5 → 5.5 V dc Input, 1W, Through Hole, +85°C Max Temp -40°C Min | RS

uk.rs-online.com

There is an article here which includes measuring AC powerline voltages with ICs such as that:

https://www.ti.com/lit/ug/tidua58/tidua58.pdf?ts=1638169683782&ref_url=https%253A%252F%252Fwww.google.co.uk%252F

 

[aomepsan]

If it's connected to other things, it must have isolation. If it's going to be a self-contained and fully insulated instrument, get it working using a low voltage AC source to start with then change the input scaling resistors to suit the final voltage range.

Isolation without a mains transformer can be done using isolation anps and a miniature DC-DC converter to run them.
eg

https://docs.rs-online.com/4296/0900766b8130f7ae.pdf

And something like this to power the input stage:

RFM-0505S | Recom RFM DC-DC Converter, 5V dc/ 200mA Output, 4.5 → 5.5 V dc Input, 1W, Through Hole, +85°C Max Temp -40°C Min | RS

uk.rs-online.com

There is an article here which includes measuring AC powerline voltages with ICs such as that:

https://www.ti.com/lit/ug/tidua58/tidua58.pdf?ts=1638169683782&ref_url=https%253A%252F%252Fwww.google.co.uk%252F

Do you have any example circuit about it? Because mine is doesn't work.
By the way, the article PDF is high level. I don't know which circuit to use