analog data link, with 6 to 12kV isolation

[Rick C]

On Tuesday, November 5, 2019 at 8:52:01 AM UTC-5, Winfield Hill wrote:

Rick C wrote...

On Sunday, November 3, 2019, Winfield Hill wrote:
I need to make a simple analog data link, with 6 to 12kV
isolation capability. By simple, I mean 0.1% resolution
and 0.1% FS DC offset error, and maybe 20kHz bandwidth.
The goal is a scope-ready signal for our electrospinning
currents: 500nA FS, with less than 0.5nA noise and drift.

I'm thinking of using an ads1202 delta-sigma modulator,
and download its digital signal with an opi1268 coupler,
good to 16kV. See the datasheets in the dropbox folder.
We can run the modulator at 2MHz, the fastest speed the
coupler can handle. I'd like to use a simple low-pass
filter to convert the modulated signal to a DC voltage.
This means reconstituting the signal, while avoiding
problems from unequal rise and fall delays. But I have
a simple signal coding scheme in mind for doing that.

To me this seems complex. Why bother with all these messy
bits when a $4 CODEC can be used at each end?

You know of a 12kV CODEC for $4?

Huh? Not sure what you are talking about. What is a 12 kV CODEC?

If you mean isolation, you don't seem to understand. I say CODEC for the generic ADC or DAC or a combination. The point is an ADC will easily produce the accuracy you need in a digital stream. Most such devices need a couple of signals to flag the samples and a bit clock. Not sure why I thought this would be four instead of three. But it is easy to combine them into a single bit stream at about twice the bit rate such as Manchester encoding.

I guess you would need to either convey four signals across
the opto interface or use a simple, small $4 FPGA to encode
the samples into a single data stream.

Yes, my plan is to encode MCLK and MDAT into one line.

But why a delta-sigma modulator instead of an ADC and DAC?

--

Rick C.

+ Get 1,000 miles of free Supercharging
+ Tesla referral code - https://ts.la/richard11209

 

[John S]

On 11/3/2019 2:40 PM, Winfield Hill wrote:

I need to make a simple analog data link, with 6 to 12kV
isolation capability. By simple, I mean 0.1% resolution
and 0.1% FS DC offset error, and maybe 20kHz bandwidth.
The goal is a scope-ready signal for our electrospinning
currents: 500nA FS, with less than 0.5nA noise and drift.

https://www.dropbox.com/sh/904n7auy3haeu3l/AAAlwbe5zCgHkJCwGrvHuEawa?dl=1

I'm thinking of using an ads1202 delta-sigma modulator,
and download its digital signal with an opi1268 coupler,
good to 16kV. See the datasheets in the dropbox folder.
We can run the modulator at 2MHz, the fastest speed the
coupler can handle. I'd like to use a simple low-pass
filter to convert the modulated signal to a DC voltage.
This means reconstituting the signal, while avoiding
problems from unequal rise and fall delays. But I have
a simple signal coding scheme in mind for doing that.

Hi, Win -

Would a Bluetooth link work?

John

 

[Joerg]

On 2019-11-03 12:40, Winfield Hill wrote:

I need to make a simple analog data link, with 6 to 12kV
isolation capability. By simple, I mean 0.1% resolution
and 0.1% FS DC offset error, and maybe 20kHz bandwidth.
The goal is a scope-ready signal for our electrospinning
currents: 500nA FS, with less than 0.5nA noise and drift.

https://www.dropbox.com/sh/904n7auy3haeu3l/AAAlwbe5zCgHkJCwGrvHuEawa?dl=1

I'm thinking of using an ads1202 delta-sigma modulator,
and download its digital signal with an opi1268 coupler,
good to 16kV.

https://www.ttelectronics.com/TTElectronics/media/ProductFiles/Optoelectronics/Datasheets/OPI1268.pdf

As I had mentioned before, read the fine print, in this case on page 2:

Quote "(2) UL recognition is for 16kV dc for one minute".

As is unfortunately customary these days I do not see a working voltage
in the datasheet so you'd have to get that from the manufacturer,
preferably in writing.

... See the datasheets in the dropbox folder.
We can run the modulator at 2MHz, the fastest speed the
coupler can handle. I'd like to use a simple low-pass
filter to convert the modulated signal to a DC voltage.
This means reconstituting the signal, while avoiding
problems from unequal rise and fall delays. But I have
a simple signal coding scheme in mind for doing that.

I'd either PW-modulate it or send it across a barrier via RF carrier
(FM-modulated). The barrier could be a loopp antenna setup on both sides
or maybe a fiber.

--
Regards, Joerg

http://www.analogconsultants.com/

 

On Sunday, November 3, 2019 at 3:40:29 PM UTC-5, Winfield Hill wrote:

I need to make a simple analog data link, with 6 to 12kV
isolation capability. By simple, I mean 0.1% resolution
and 0.1% FS DC offset error, and maybe 20kHz bandwidth.
The goal is a scope-ready signal for our electrospinning
currents: 500nA FS, with less than 0.5nA noise and drift.

https://www.dropbox.com/sh/904n7auy3haeu3l/AAAlwbe5zCgHkJCwGrvHuEawa?dl=1

I'm thinking of using an ads1202 delta-sigma modulator,
and download its digital signal with an opi1268 coupler,
good to 16kV. See the datasheets in the dropbox folder.
We can run the modulator at 2MHz, the fastest speed the
coupler can handle. I'd like to use a simple low-pass
filter to convert the modulated signal to a DC voltage.
This means reconstituting the signal, while avoiding
problems from unequal rise and fall delays. But I have
a simple signal coding scheme in mind for doing that.


--
Thanks,
- Win

Self-contained near field magnetic induction channels have come into their own. Power consumption looks a lot better than achievable with optical. And the 12kV isolation is well within its range. SNR specs shown below support 12-bit resolution with 20dB to spare and they have plenty of bandwidth for your application. Unfortunately some programming is required.
https://www.futureelectronics.com/resources/get-connected/2017-06/future-electronics-near-field-magnetic-induction
Not at all sure about external field immunity and your application. Maybe better to stick with technology you're familiar with.

 

[John Larkin]

On Wed, 6 Nov 2019 12:33:30 -0800 (PST),
bloggs.fredbloggs.fred@gmail.com wrote:

On Sunday, November 3, 2019 at 3:40:29 PM UTC-5, Winfield Hill wrote:
I need to make a simple analog data link, with 6 to 12kV
isolation capability. By simple, I mean 0.1% resolution
and 0.1% FS DC offset error, and maybe 20kHz bandwidth.
The goal is a scope-ready signal for our electrospinning
currents: 500nA FS, with less than 0.5nA noise and drift.

https://www.dropbox.com/sh/904n7auy3haeu3l/AAAlwbe5zCgHkJCwGrvHuEawa?dl=1

I'm thinking of using an ads1202 delta-sigma modulator,
and download its digital signal with an opi1268 coupler,
good to 16kV. See the datasheets in the dropbox folder.
We can run the modulator at 2MHz, the fastest speed the
coupler can handle. I'd like to use a simple low-pass
filter to convert the modulated signal to a DC voltage.
This means reconstituting the signal, while avoiding
problems from unequal rise and fall delays. But I have
a simple signal coding scheme in mind for doing that.


--
Thanks,
- Win

Self-contained near field magnetic induction channels have come into their own. Power consumption looks a lot better than achievable with optical. And the 12kV isolation is well within its range. SNR specs shown below support 12-bit resolution with 20dB to spare and they have plenty of bandwidth for your application. Unfortunately some programming is required.
https://www.futureelectronics.com/resources/get-connected/2017-06/future-electronics-near-field-magnetic-induction
Not at all sure about external field immunity and your application. Maybe better to stick with technology you're familiar with.

An unshielded drum core inductor is a damned fine magnetic field
sprayer.

Put one on each side of a PCB maybe.
--

John Larkin Highland Technology, Inc
picosecond timing precision measurement

jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com

 

[whit3rd]

On Wednesday, November 6, 2019 at 12:33:34 PM UTC-8, bloggs.fre...@gmail.com wrote:

On Sunday, November 3, 2019 at 3:40:29 PM UTC-5, Winfield Hill wrote:

I need to make a simple analog data link, with 6 to 12kV
isolation capability

Self-contained near field magnetic induction channels have come into their own....
Not at all sure about external field immunity and your application. Maybe better to stick with technology you're familiar with.

When you're generating ions, which might indicate conduction in the medium, an inductive coupling
through that medium is ... dicey, to say the least.