isolated delta-sigma converters

J

John Larkin

Guest
https://www.analog.com/en/products/adum7703.html#product-overview

and the similar

http://www.ti.com/product/AMC1106E05

This is cool. I can hang a current shunt and a voltage divider on my
transformer output, and the isolated delta-sigma data streams can go
straight into an FPGA without an ADC.

They need DC power on the isolated side, which is a minor nuisance.


--

John Larkin Highland Technology, Inc
picosecond timing precision measurement

jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com
 
lørdag den 15. juni 2019 kl. 00.51.48 UTC+2 skrev boB:
On Fri, 14 Jun 2019 11:32:52 -0700, John Larkin
jjlarkin@highland_snip_technology.com> wrote:


https://www.analog.com/en/products/adum7703.html#product-overview

and the similar

http://www.ti.com/product/AMC1106E05

This is cool. I can hang a current shunt and a voltage divider on my
transformer output, and the isolated delta-sigma data streams can go
straight into an FPGA without an ADC.

They need DC power on the isolated side, which is a minor nuisance.


Didn't look at this particular spec sheet but the isolated mode
Delta-Smegma converters I have seen are the stream of the input
modulator before any sigma part of the operation so is just high
frequency delta modulation data which shouold work great.

which ones have you seen that use delta modulation?

both datasheets says second-order delta-sigma modulator
 
On Fri, 14 Jun 2019 11:32:52 -0700, John Larkin
<jjlarkin@highland_snip_technology.com> wrote:

https://www.analog.com/en/products/adum7703.html#product-overview

and the similar

http://www.ti.com/product/AMC1106E05

This is cool. I can hang a current shunt and a voltage divider on my
transformer output, and the isolated delta-sigma data streams can go
straight into an FPGA without an ADC.

They need DC power on the isolated side, which is a minor nuisance.

Didn't look at this particular spec sheet but the isolated mode
Delta-Smegma converters I have seen are the stream of the input
modulator before any sigma part of the operation so is just high
frequency delta modulation data which shouold work great.

I also remember that they aren't real cheap for whatever reason more
than likely, especially AD I would suspect.
 
On Fri, 14 Jun 2019 11:32:52 -0700, John Larkin
<jjlarkin@highland_snip_technology.com> wrote:

https://www.analog.com/en/products/adum7703.html#product-overview

and the similar

http://www.ti.com/product/AMC1106E05

This is cool. I can hang a current shunt and a voltage divider on my
transformer output, and the isolated delta-sigma data streams can go
straight into an FPGA without an ADC.

They need DC power on the isolated side, which is a minor nuisance.

We use the ADuM analog Part (adm3251 - for rs232). They work, no
problems. They seem to be quiet too, the data sheet give a recomended
layout for EMI. I wonder how that affects the ADC.

Cheers
 
On Fri, 14 Jun 2019 15:51:50 -0700, boB <boB@K7IQ.com> wrote:

On Fri, 14 Jun 2019 11:32:52 -0700, John Larkin
jjlarkin@highland_snip_technology.com> wrote:


https://www.analog.com/en/products/adum7703.html#product-overview

and the similar

http://www.ti.com/product/AMC1106E05

This is cool. I can hang a current shunt and a voltage divider on my
transformer output, and the isolated delta-sigma data streams can go
straight into an FPGA without an ADC.

They need DC power on the isolated side, which is a minor nuisance.


Didn't look at this particular spec sheet but the isolated mode
Delta-Smegma converters I have seen are the stream of the input
modulator before any sigma part of the operation so is just high
frequency delta modulation data which shouold work great.

I also remember that they aren't real cheap for whatever reason more
than likely, especially AD I would suspect.

The ADI is around $5 at 100, and the TI is a bit less. Looks like the
ADI is a bit better electrically.

Looks like all the FPGA has to do is lowpass filter the bit stream.


--

John Larkin Highland Technology, Inc
picosecond timing precision measurement

jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com
 
John Larkin wrote...
https://www.analog.com/en/products/adum7703.html#product-overview
and the similar
http://www.ti.com/product/AMC1106E05

This is cool. I can hang a current shunt ...

Yes it's cool. I've been tracking these for a
few years now, and I'm appalled at their poor
DC accuracy. About 0.1% for the TI part, and
only a little better for the AD part. Sheesh,
the whole input switching nature of these ADCs
cries out for the input-reversing schemes that
drives DC offsets down into the low uV region.
It's not as if they aren't charging big bucks.

I'm surprised the motor-driver blokes put up
with it. They often run motors at low torques,
don't they need absolute polarity control?


--
Thanks,
- Win
 
On 14 Jun 2019 19:33:12 -0700, Winfield Hill <winfieldhill@yahoo.com>
wrote:

John Larkin wrote...


https://www.analog.com/en/products/adum7703.html#product-overview
and the similar
http://www.ti.com/product/AMC1106E05

This is cool. I can hang a current shunt ...

Yes it's cool. I've been tracking these for a
few years now, and I'm appalled at their poor
DC accuracy. About 0.1% for the TI part, and
only a little better for the AD part. Sheesh,
the whole input switching nature of these ADCs
cries out for the input-reversing schemes that
drives DC offsets down into the low uV region.
It's not as if they aren't charging big bucks.

I'm surprised the motor-driver blokes put up
with it. They often run motors at low torques,
don't they need absolute polarity control?

ADI claims 130 uV max offset with very low drift. One could always
zero it when the current is known to be off.

I'm measuring AC!


--

John Larkin Highland Technology, Inc

lunatic fringe electronics
 
On Fri, 14 Jun 2019 16:18:13 -0700 (PDT), Lasse Langwadt Christensen
<langwadt@fonz.dk> wrote:

lřrdag den 15. juni 2019 kl. 00.51.48 UTC+2 skrev boB:
On Fri, 14 Jun 2019 11:32:52 -0700, John Larkin
jjlarkin@highland_snip_technology.com> wrote:


https://www.analog.com/en/products/adum7703.html#product-overview

and the similar

http://www.ti.com/product/AMC1106E05

This is cool. I can hang a current shunt and a voltage divider on my
transformer output, and the isolated delta-sigma data streams can go
straight into an FPGA without an ADC.

They need DC power on the isolated side, which is a minor nuisance.


Didn't look at this particular spec sheet but the isolated mode
Delta-Smegma converters I have seen are the stream of the input
modulator before any sigma part of the operation so is just high
frequency delta modulation data which shouold work great.

which ones have you seen that use delta modulation?

both datasheets says second-order delta-sigma modulator

First or second order delta modulation I put in the same catagory but
it's just better with 2nd order.

Sigma portion done after the delta mod serial string of 1's and 0s
have been transferred over the isolation barrier at high frequency.

Forgot about powering the delta modulators. Yeah, that's a pain but
not too big of issue.
 
On 2019-06-14 20:32, John Larkin wrote:
https://www.analog.com/en/products/adum7703.html#product-overview

and the similar

http://www.ti.com/product/AMC1106E05

This is cool. I can hang a current shunt and a voltage divider on my
transformer output, and the isolated delta-sigma data streams can go
straight into an FPGA without an ADC.

They need DC power on the isolated side, which is a minor nuisance.

I did a 32 floating channel design long time ago where the 100 kHz DC/DC
conversion was clocked by a timer on the CPU side of things. The
transformer output on the floating side was also the delta conversion
clock. Saved an 'expensive' opto-coupler per channel. Sigma parts were
just 4 counters in the CPU (1:8 multiplexed to get 32 channels). Got a
nice linear 14 bit conversion out of that.

Arie
 
lørdag den 15. juni 2019 kl. 08.09.10 UTC+2 skrev boB:
On Fri, 14 Jun 2019 16:18:13 -0700 (PDT), Lasse Langwadt Christensen
langwadt@fonz.dk> wrote:

lørdag den 15. juni 2019 kl. 00.51.48 UTC+2 skrev boB:
On Fri, 14 Jun 2019 11:32:52 -0700, John Larkin
jjlarkin@highland_snip_technology.com> wrote:


https://www.analog.com/en/products/adum7703.html#product-overview

and the similar

http://www.ti.com/product/AMC1106E05

This is cool. I can hang a current shunt and a voltage divider on my
transformer output, and the isolated delta-sigma data streams can go
straight into an FPGA without an ADC.

They need DC power on the isolated side, which is a minor nuisance.


Didn't look at this particular spec sheet but the isolated mode
Delta-Smegma converters I have seen are the stream of the input
modulator before any sigma part of the operation so is just high
frequency delta modulation data which shouold work great.

which ones have you seen that use delta modulation?

both datasheets says second-order delta-sigma modulator


First or second order delta modulation I put in the same catagory but
it's just better with 2nd order.

Sigma portion done after the delta mod serial string of 1's and 0s
have been transferred over the isolation barrier at high frequency.

delta and delta-sigma are related but different things
 
On Sat, 15 Jun 2019 06:21:07 -0700 (PDT), Lasse Langwadt Christensen
<langwadt@fonz.dk> wrote:

lřrdag den 15. juni 2019 kl. 08.09.10 UTC+2 skrev boB:
On Fri, 14 Jun 2019 16:18:13 -0700 (PDT), Lasse Langwadt Christensen
langwadt@fonz.dk> wrote:

lřrdag den 15. juni 2019 kl. 00.51.48 UTC+2 skrev boB:
On Fri, 14 Jun 2019 11:32:52 -0700, John Larkin
jjlarkin@highland_snip_technology.com> wrote:


https://www.analog.com/en/products/adum7703.html#product-overview

and the similar

http://www.ti.com/product/AMC1106E05

This is cool. I can hang a current shunt and a voltage divider on my
transformer output, and the isolated delta-sigma data streams can go
straight into an FPGA without an ADC.

They need DC power on the isolated side, which is a minor nuisance.


Didn't look at this particular spec sheet but the isolated mode
Delta-Smegma converters I have seen are the stream of the input
modulator before any sigma part of the operation so is just high
frequency delta modulation data which shouold work great.

which ones have you seen that use delta modulation?

both datasheets says second-order delta-sigma modulator


First or second order delta modulation I put in the same catagory but
it's just better with 2nd order.

Sigma portion done after the delta mod serial string of 1's and 0s
have been transferred over the isolation barrier at high frequency.

delta and delta-sigma are related but different things

Yes, of course they are. Delta modulation is the input which is sent
usually to a DSP for decimation to turn the HF oversampled delta
modulation input to a lower frequency wider bit width.

We used, new at the time, Crystal semiconductor oversampling
converters in the audio business in the 1980s. Single order Delta-mod
to start with. Amazingly good stuff and I was "converted" almost
immediately. Those chips had a test pin that was the delta modulator
output up at somewhere around 3 MHz.
 
lørdag den 15. juni 2019 kl. 21.19.11 UTC+2 skrev boB:
On Sat, 15 Jun 2019 06:21:07 -0700 (PDT), Lasse Langwadt Christensen
langwadt@fonz.dk> wrote:

lørdag den 15. juni 2019 kl. 08.09.10 UTC+2 skrev boB:
On Fri, 14 Jun 2019 16:18:13 -0700 (PDT), Lasse Langwadt Christensen
langwadt@fonz.dk> wrote:

lørdag den 15. juni 2019 kl. 00.51.48 UTC+2 skrev boB:
On Fri, 14 Jun 2019 11:32:52 -0700, John Larkin
jjlarkin@highland_snip_technology.com> wrote:


https://www.analog.com/en/products/adum7703.html#product-overview

and the similar

http://www.ti.com/product/AMC1106E05

This is cool. I can hang a current shunt and a voltage divider on my
transformer output, and the isolated delta-sigma data streams can go
straight into an FPGA without an ADC.

They need DC power on the isolated side, which is a minor nuisance..


Didn't look at this particular spec sheet but the isolated mode
Delta-Smegma converters I have seen are the stream of the input
modulator before any sigma part of the operation so is just high
frequency delta modulation data which shouold work great.

which ones have you seen that use delta modulation?

both datasheets says second-order delta-sigma modulator


First or second order delta modulation I put in the same catagory but
it's just better with 2nd order.

Sigma portion done after the delta mod serial string of 1's and 0s
have been transferred over the isolation barrier at high frequency.

delta and delta-sigma are related but different things


Yes, of course they are. Delta modulation is the input which is sent
usually to a DSP for decimation to turn the HF oversampled delta
modulation input to a lower frequency wider bit width.

delta modulation and delta-sigma modulation is not the same thing
 
lørdag den 15. juni 2019 kl. 22.56.56 UTC+2 skrev boB:
On Sat, 15 Jun 2019 13:25:16 -0700 (PDT), Lasse Langwadt Christensen
langwadt@fonz.dk> wrote:

lørdag den 15. juni 2019 kl. 21.19.11 UTC+2 skrev boB:
On Sat, 15 Jun 2019 06:21:07 -0700 (PDT), Lasse Langwadt Christensen
langwadt@fonz.dk> wrote:

lørdag den 15. juni 2019 kl. 08.09.10 UTC+2 skrev boB:
On Fri, 14 Jun 2019 16:18:13 -0700 (PDT), Lasse Langwadt Christensen
langwadt@fonz.dk> wrote:

lørdag den 15. juni 2019 kl. 00.51.48 UTC+2 skrev boB:
On Fri, 14 Jun 2019 11:32:52 -0700, John Larkin
jjlarkin@highland_snip_technology.com> wrote:


https://www.analog.com/en/products/adum7703.html#product-overview

and the similar

http://www.ti.com/product/AMC1106E05

This is cool. I can hang a current shunt and a voltage divider on my
transformer output, and the isolated delta-sigma data streams can go
straight into an FPGA without an ADC.

They need DC power on the isolated side, which is a minor nuisance.


Didn't look at this particular spec sheet but the isolated mode
Delta-Smegma converters I have seen are the stream of the input
modulator before any sigma part of the operation so is just high
frequency delta modulation data which shouold work great.

which ones have you seen that use delta modulation?

both datasheets says second-order delta-sigma modulator


First or second order delta modulation I put in the same catagory but
it's just better with 2nd order.

Sigma portion done after the delta mod serial string of 1's and 0s
have been transferred over the isolation barrier at high frequency.

delta and delta-sigma are related but different things


Yes, of course they are. Delta modulation is the input which is sent
usually to a DSP for decimation to turn the HF oversampled delta
modulation input to a lower frequency wider bit width.


delta modulation and delta-sigma modulation is not the same thing

Meant to say the AREN'T.

The SIGMA part isn't part of the modulation though. It's processing
of the delta modulation.

yes it is, delta = difference, sigma = integrator

https://wiki.analog.com/_media/university/courses/electronics/a17_f1.png
 
On Sat, 15 Jun 2019 13:25:16 -0700 (PDT), Lasse Langwadt Christensen
<langwadt@fonz.dk> wrote:

lřrdag den 15. juni 2019 kl. 21.19.11 UTC+2 skrev boB:
On Sat, 15 Jun 2019 06:21:07 -0700 (PDT), Lasse Langwadt Christensen
langwadt@fonz.dk> wrote:

lřrdag den 15. juni 2019 kl. 08.09.10 UTC+2 skrev boB:
On Fri, 14 Jun 2019 16:18:13 -0700 (PDT), Lasse Langwadt Christensen
langwadt@fonz.dk> wrote:

lřrdag den 15. juni 2019 kl. 00.51.48 UTC+2 skrev boB:
On Fri, 14 Jun 2019 11:32:52 -0700, John Larkin
jjlarkin@highland_snip_technology.com> wrote:


https://www.analog.com/en/products/adum7703.html#product-overview

and the similar

http://www.ti.com/product/AMC1106E05

This is cool. I can hang a current shunt and a voltage divider on my
transformer output, and the isolated delta-sigma data streams can go
straight into an FPGA without an ADC.

They need DC power on the isolated side, which is a minor nuisance.


Didn't look at this particular spec sheet but the isolated mode
Delta-Smegma converters I have seen are the stream of the input
modulator before any sigma part of the operation so is just high
frequency delta modulation data which shouold work great.

which ones have you seen that use delta modulation?

both datasheets says second-order delta-sigma modulator


First or second order delta modulation I put in the same catagory but
it's just better with 2nd order.

Sigma portion done after the delta mod serial string of 1's and 0s
have been transferred over the isolation barrier at high frequency.

delta and delta-sigma are related but different things


Yes, of course they are. Delta modulation is the input which is sent
usually to a DSP for decimation to turn the HF oversampled delta
modulation input to a lower frequency wider bit width.


delta modulation and delta-sigma modulation is not the same thing

Actually, I'm not sure why you even mention this ?
 
On Sat, 15 Jun 2019 13:25:16 -0700 (PDT), Lasse Langwadt Christensen
<langwadt@fonz.dk> wrote:

lřrdag den 15. juni 2019 kl. 21.19.11 UTC+2 skrev boB:
On Sat, 15 Jun 2019 06:21:07 -0700 (PDT), Lasse Langwadt Christensen
langwadt@fonz.dk> wrote:

lřrdag den 15. juni 2019 kl. 08.09.10 UTC+2 skrev boB:
On Fri, 14 Jun 2019 16:18:13 -0700 (PDT), Lasse Langwadt Christensen
langwadt@fonz.dk> wrote:

lřrdag den 15. juni 2019 kl. 00.51.48 UTC+2 skrev boB:
On Fri, 14 Jun 2019 11:32:52 -0700, John Larkin
jjlarkin@highland_snip_technology.com> wrote:


https://www.analog.com/en/products/adum7703.html#product-overview

and the similar

http://www.ti.com/product/AMC1106E05

This is cool. I can hang a current shunt and a voltage divider on my
transformer output, and the isolated delta-sigma data streams can go
straight into an FPGA without an ADC.

They need DC power on the isolated side, which is a minor nuisance.


Didn't look at this particular spec sheet but the isolated mode
Delta-Smegma converters I have seen are the stream of the input
modulator before any sigma part of the operation so is just high
frequency delta modulation data which shouold work great.

which ones have you seen that use delta modulation?

both datasheets says second-order delta-sigma modulator


First or second order delta modulation I put in the same catagory but
it's just better with 2nd order.

Sigma portion done after the delta mod serial string of 1's and 0s
have been transferred over the isolation barrier at high frequency.

delta and delta-sigma are related but different things


Yes, of course they are. Delta modulation is the input which is sent
usually to a DSP for decimation to turn the HF oversampled delta
modulation input to a lower frequency wider bit width.


delta modulation and delta-sigma modulation is not the same thing

Meant to say the AREN'T.

The SIGMA part isn't part of the modulation though. It's processing
of the delta modulation.
 
On Sat, 15 Jun 2019 14:01:41 -0700, boB <boB@K7IQ.com> wrote:

On Sat, 15 Jun 2019 13:25:16 -0700 (PDT), Lasse Langwadt Christensen
langwadt@fonz.dk> wrote:

lřrdag den 15. juni 2019 kl. 21.19.11 UTC+2 skrev boB:
On Sat, 15 Jun 2019 06:21:07 -0700 (PDT), Lasse Langwadt Christensen
langwadt@fonz.dk> wrote:

lřrdag den 15. juni 2019 kl. 08.09.10 UTC+2 skrev boB:
On Fri, 14 Jun 2019 16:18:13 -0700 (PDT), Lasse Langwadt Christensen
langwadt@fonz.dk> wrote:

lřrdag den 15. juni 2019 kl. 00.51.48 UTC+2 skrev boB:
On Fri, 14 Jun 2019 11:32:52 -0700, John Larkin
jjlarkin@highland_snip_technology.com> wrote:


https://www.analog.com/en/products/adum7703.html#product-overview

and the similar

http://www.ti.com/product/AMC1106E05

This is cool. I can hang a current shunt and a voltage divider on my
transformer output, and the isolated delta-sigma data streams can go
straight into an FPGA without an ADC.

They need DC power on the isolated side, which is a minor nuisance.


Didn't look at this particular spec sheet but the isolated mode
Delta-Smegma converters I have seen are the stream of the input
modulator before any sigma part of the operation so is just high
frequency delta modulation data which shouold work great.

which ones have you seen that use delta modulation?

both datasheets says second-order delta-sigma modulator


First or second order delta modulation I put in the same catagory but
it's just better with 2nd order.

Sigma portion done after the delta mod serial string of 1's and 0s
have been transferred over the isolation barrier at high frequency.

delta and delta-sigma are related but different things


Yes, of course they are. Delta modulation is the input which is sent
usually to a DSP for decimation to turn the HF oversampled delta
modulation input to a lower frequency wider bit width.


delta modulation and delta-sigma modulation is not the same thing


Actually, I'm not sure why you even mention this ?

But I do see why you did bring it up. Good stuff.


>
 
On Sat, 15 Jun 2019 14:06:24 -0700 (PDT), Lasse Langwadt Christensen
<langwadt@fonz.dk> wrote:

lřrdag den 15. juni 2019 kl. 22.56.56 UTC+2 skrev boB:
On Sat, 15 Jun 2019 13:25:16 -0700 (PDT), Lasse Langwadt Christensen
langwadt@fonz.dk> wrote:

lřrdag den 15. juni 2019 kl. 21.19.11 UTC+2 skrev boB:
On Sat, 15 Jun 2019 06:21:07 -0700 (PDT), Lasse Langwadt Christensen
langwadt@fonz.dk> wrote:

lřrdag den 15. juni 2019 kl. 08.09.10 UTC+2 skrev boB:
On Fri, 14 Jun 2019 16:18:13 -0700 (PDT), Lasse Langwadt Christensen
langwadt@fonz.dk> wrote:

lřrdag den 15. juni 2019 kl. 00.51.48 UTC+2 skrev boB:
On Fri, 14 Jun 2019 11:32:52 -0700, John Larkin
jjlarkin@highland_snip_technology.com> wrote:


https://www.analog.com/en/products/adum7703.html#product-overview

and the similar

http://www.ti.com/product/AMC1106E05

This is cool. I can hang a current shunt and a voltage divider on my
transformer output, and the isolated delta-sigma data streams can go
straight into an FPGA without an ADC.

They need DC power on the isolated side, which is a minor nuisance.


Didn't look at this particular spec sheet but the isolated mode
Delta-Smegma converters I have seen are the stream of the input
modulator before any sigma part of the operation so is just high
frequency delta modulation data which shouold work great.

which ones have you seen that use delta modulation?

both datasheets says second-order delta-sigma modulator


First or second order delta modulation I put in the same catagory but
it's just better with 2nd order.

Sigma portion done after the delta mod serial string of 1's and 0s
have been transferred over the isolation barrier at high frequency.

delta and delta-sigma are related but different things


Yes, of course they are. Delta modulation is the input which is sent
usually to a DSP for decimation to turn the HF oversampled delta
modulation input to a lower frequency wider bit width.


delta modulation and delta-sigma modulation is not the same thing

Meant to say the AREN'T.

The SIGMA part isn't part of the modulation though. It's processing
of the delta modulation.

yes it is, delta = difference, sigma = integrator

https://wiki.analog.com/_media/university/courses/electronics/a17_f1.png

Right. There is "delta-sigma"or integration involved with the 2nd
order delta-sigma modulator... But as far as this thread is
concerned, isolation, it could be single delta mod or delta-sigma
modulation but the downconverting, decimation or sigma that I was
referring to is done after the serial HF bit isolation. Integration
or addition or sigma used both places, among other processes.
It's all good
 
John Larkin <jjlarkin@highland_snip_technology.com> writes:

This is cool. I can hang a current shunt and a voltage divider on my
transformer output, and the isolated delta-sigma data streams can go
straight into an FPGA without an ADC.

Some microcontrollers (at least STM32 series have these) also have
SD-inputs, which make it easy to use SD-modulators for isolated ADC
inputs.


--
mikko
 
Winfield Hill wrote:

> Yes it's cool.

78kSPS, ENOB of 14. Yawn.
LTC1407A-1 is a 14-bit 1.5MSPS part, so decimating it by
19 to match the delta-sigma slug would bring you a tad above
2 more bits of processing gain. And you can use the fast
bitstream for overcurrent/overvoltage protection purposes.
The delta-sigma would be fast enough to report the primary side
destruction, if you are lucky. and the SAR is dual/simultaneous
sampling, so you can measure current and voltage with the same part.
I use exactly this configuration in another project for mains
synchronization and I'm planning to use it as well in a bridgeless
totem-pole PFC.

John already has an FPGA around there, so the deserialization of
the "high speed" 51MHz bitstream would be another exciting task, yawn.

Best regards, Piotr
 
Lasse Langwadt Christensen wrote:

> which ones have you seen that use delta modulation?

He probably means the decimating filter part.

Best regards, Piotr
 

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