High Voltage op amp...

[habib]

Hi all,

I need a micro power, op-amp with single supply [0...60V .. 70Vmax], I
need this for a specific test equipment for batteries, I found the
LTC2057 which would fulfill my requirements.

I appreciate if someone could give me an advice about this kind of micro
power high voltage op-amp or may be pointing me to another chip.

Best regards, H

 

[Piglet]

On 06/09/2020 10:53, habib wrote:

Hi all,

I need a micro power, op-amp with single supply [0...60V .. 70Vmax], I
need this for a specific test equipment for batteries, I found the
LTC2057 which would fulfill my requirements.

I appreciate if someone could give me an advice about this kind of micro
power high voltage op-amp or may be pointing me to another chip.

Best regards, H

The LTC2057 draws 0.8 - 1.2mA when active. It is only micro-power when
shutdown.

Can you say more about your requirements: Vos, Ib, GBW, Iq, CMR, does Iq
need to be low at all supply voltages?

piglet

 

[habib]

Le 06/09/2020 à 12:05, Piglet a écrit :

On 06/09/2020 10:53, habib wrote:
Hi all,

I need a micro power, op-amp with single supply [0...60V .. 70Vmax], I
need this for a specific test equipment for batteries, I found the
LTC2057 which would fulfill my requirements.

I appreciate if someone could give me an advice about this kind of micro
power high voltage op-amp or may be pointing me to another chip.

Best regards, H

The LTC2057 draws 0.8 - 1.2mA when active. It is only micro-power when
shutdown.

I mean micro power \'cause it\'s not a power amp I need, 1mA or so is just
ok for the application.

Can you say more about your requirements: Vos, Ib, GBW, Iq, CMR, does Iq
need to be low at all supply voltages?

It just need to be a op-amp with rail to rail output, no specific
requirements for parameters Iq, CMR, GBW ... etc. No stability for
output capacitance is needed.

piglet

Best regards, H

 

[Martin Brown]

On 06/09/2020 10:53, habib wrote:

Hi all,

I need a micro power, op-amp with single supply [0...60V .. 70Vmax], I
need this for a specific test equipment for batteries, I found the
LTC2057 which would fulfill my requirements.

I appreciate if someone could give me an advice about this kind of micro
power high voltage op-amp or may be pointing me to another chip.

Best regards, H

This bootstrapping trick might do what you want with a fairly normal
part and a few discrete components to handle the voltages.

https://www.analog.com/media/en/analog-dialogue/raqs/raq-issue-168.pdf

Cruder versions are available. For once EDN comes good :

https://www.edn.com/bootstrapping-your-op-amp-yields-wide-voltage-swings/

How close to rail to rail it is depends on your choice of opamp.

--
Regards,
Martin Brown

 

[habib]

Le 06/09/2020 à 14:28, Martin Brown a écrit :

https://www.edn.com/bootstrapping-your-op-amp-yields-wide-voltage-swings/

How close to rail to rail it is depends on your choice of opamp.

Good ! Boostrapping from op amp output is one of ideas I did not
remember, thanks.

Single supply [0..60V .. 70Vmax] is a requirement.

Unfortunately my design shall become complicated if I design symmetrical
power supplies for the analog blocks of the test bench, nevertheless I
will see if it is possible.

Thanks for the idea, H

 

[server]

On Sun, 6 Sep 2020 11:53:18 +0200, habib <h.bouazizviallet@free.fr>
wrote:

Hi all,

I need a micro power, op-amp with single supply [0...60V .. 70Vmax], I
need this for a specific test equipment for batteries, I found the
LTC2057 which would fulfill my requirements.

I appreciate if someone could give me an advice about this kind of micro
power high voltage op-amp or may be pointing me to another chip.

Best regards, H

This is my minimalist HV amp:

https://www.dropbox.com/s/w8px8z9mf64wpc9/HVamp.JPG?raw=1

With a little tweaking, the opamp supply current can be made
arbitrarily low. The output can be run pure class-B, so the only
current there is whatever the load needs.






--

John Larkin Highland Technology, Inc

Science teaches us to doubt.

Claude Bernard

 

[Chris]

On 09/06/20 13:28, Martin Brown wrote:

On 06/09/2020 10:53, habib wrote:
Hi all,

I need a micro power, op-amp with single supply [0...60V .. 70Vmax], I
need this for a specific test equipment for batteries, I found the
LTC2057 which would fulfill my requirements.

I appreciate if someone could give me an advice about this kind of
micro power high voltage op-amp or may be pointing me to another chip.

Best regards, H

This bootstrapping trick might do what you want with a fairly normal
part and a few discrete components to handle the voltages.

https://www.analog.com/media/en/analog-dialogue/raqs/raq-issue-168.pdf

Cruder versions are available. For once EDN comes good :

https://www.edn.com/bootstrapping-your-op-amp-yields-wide-voltage-swings/

How close to rail to rail it is depends on your choice of opamp.

Fluke used the second idea in their 5200 ac calibrator output power
amplifer. Neat bit of circuit design...

Chris

 

[server]

On Sunday, 6 September 2020 16:31:56 UTC+1, jla...@highlandsniptechnology.com wrote:

On Sun, 6 Sep 2020 11:53:18 +0200, habib <h.bouazizviallet@free.fr
wrote:

Hi all,

I need a micro power, op-amp with single supply [0...60V .. 70Vmax], I
need this for a specific test equipment for batteries, I found the
LTC2057 which would fulfill my requirements.

I appreciate if someone could give me an advice about this kind of micro
power high voltage op-amp or may be pointing me to another chip.

Best regards, H

This is my minimalist HV amp:

https://www.dropbox.com/s/w8px8z9mf64wpc9/HVamp.JPG?raw=1

With a little tweaking, the opamp supply current can be made
arbitrarily low. The output can be run pure class-B, so the only
current there is whatever the load needs.

John Larkin Highland Technology, Inc

Putting opo-isolator LEDs in the supply rails of an op-amp and loading
the output with a resistor is a very neat trick. I first came across
it in a Burr Brown linear opto-isolator hybrid module in the late 1970s
but it may well be much older than that.
The data sheet of the isolator module does not even hint that this
is how it works, but I dismantled a broken one to find out how
they did it. I could dig out the part number if anyone is interested.

John

 

[Chris]

On 09/07/20 11:19, jrwalliker@gmail.com wrote:

On Sunday, 6 September 2020 16:31:56 UTC+1, jla...@highlandsniptechnology.com wrote:
On Sun, 6 Sep 2020 11:53:18 +0200, habib<h.bouazizviallet@free.fr
wrote:

Hi all,

I need a micro power, op-amp with single supply [0...60V .. 70Vmax], I
need this for a specific test equipment for batteries, I found the
LTC2057 which would fulfill my requirements.

I appreciate if someone could give me an advice about this kind of micro
power high voltage op-amp or may be pointing me to another chip.

Best regards, H

This is my minimalist HV amp:

https://www.dropbox.com/s/w8px8z9mf64wpc9/HVamp.JPG?raw=1

With a little tweaking, the opamp supply current can be made
arbitrarily low. The output can be run pure class-B, so the only
current there is whatever the load needs.

John Larkin Highland Technology, Inc

Putting opo-isolator LEDs in the supply rails of an op-amp and loading
the output with a resistor is a very neat trick. I first came across
it in a Burr Brown linear opto-isolator hybrid module in the late 1970s
but it may well be much older than that.
The data sheet of the isolator module does not even hint that this
is how it works, but I dismantled a broken one to find out how
they did it. I could dig out the part number if anyone is interested.

John

Neat idea, but stability of the output stage quiescent current and
power dissipation might be an issue.

Also, need some way of closing the loop back to the op map, so
another opto isolator ?...

Chris

 

[server]

On Monday, 7 September 2020 14:49:20 UTC+1, Chris wrote:

On 09/07/20 11:19, jrwalliker@gmail.com wrote:
On Sunday, 6 September 2020 16:31:56 UTC+1, jla...@highlandsniptechnology.com wrote:
On Sun, 6 Sep 2020 11:53:18 +0200, habib<h.bouazizviallet@free.fr
wrote:

Hi all,

I need a micro power, op-amp with single supply [0...60V .. 70Vmax], I
need this for a specific test equipment for batteries, I found the
LTC2057 which would fulfill my requirements.

I appreciate if someone could give me an advice about this kind of micro
power high voltage op-amp or may be pointing me to another chip.

Best regards, H

This is my minimalist HV amp:

https://www.dropbox.com/s/w8px8z9mf64wpc9/HVamp.JPG?raw=1

With a little tweaking, the opamp supply current can be made
arbitrarily low. The output can be run pure class-B, so the only
current there is whatever the load needs.

John Larkin Highland Technology, Inc

Putting opo-isolator LEDs in the supply rails of an op-amp and loading
the output with a resistor is a very neat trick. I first came across
it in a Burr Brown linear opto-isolator hybrid module in the late 1970s
but it may well be much older than that.
The data sheet of the isolator module does not even hint that this
is how it works, but I dismantled a broken one to find out how
they did it. I could dig out the part number if anyone is interested.

John

Neat idea, but stability of the output stage quiescent current and
power dissipation might be an issue.

Also, need some way of closing the loop back to the op map, so
another opto isolator ?...

Chris

That is exactly what they did.
Two optical cavities, each containing an LED and two matched photodiodes.
One photodiode in each cavity provides feedback to the driver op-amp and
the other photodiode is on the other side of the isolation barrier.
One optical cavity for positive signals and the other cavity for negative.
The overall result was reasonably good dc stability and linearity.
Bandwidth was several kilohertz. I once combined these with audio
transformers to make a multi-channel medical isolator with a linear
phase response from dc to well beyond 20kHz. Probably around 50kHz.

 

[John Larkin]

On Mon, 7 Sep 2020 09:17:08 -0700 (PDT), jrwalliker@gmail.com wrote:

On Monday, 7 September 2020 14:49:20 UTC+1, Chris wrote:
On 09/07/20 11:19, jrwalliker@gmail.com wrote:
On Sunday, 6 September 2020 16:31:56 UTC+1, jla...@highlandsniptechnology.com wrote:
On Sun, 6 Sep 2020 11:53:18 +0200, habib<h.bouazizviallet@free.fr
wrote:

Hi all,

I need a micro power, op-amp with single supply [0...60V .. 70Vmax], I
need this for a specific test equipment for batteries, I found the
LTC2057 which would fulfill my requirements.

I appreciate if someone could give me an advice about this kind of micro
power high voltage op-amp or may be pointing me to another chip.

Best regards, H

This is my minimalist HV amp:

https://www.dropbox.com/s/w8px8z9mf64wpc9/HVamp.JPG?raw=1

With a little tweaking, the opamp supply current can be made
arbitrarily low. The output can be run pure class-B, so the only
current there is whatever the load needs.

John Larkin Highland Technology, Inc

Putting opo-isolator LEDs in the supply rails of an op-amp and loading
the output with a resistor is a very neat trick. I first came across
it in a Burr Brown linear opto-isolator hybrid module in the late 1970s
but it may well be much older than that.
The data sheet of the isolator module does not even hint that this
is how it works, but I dismantled a broken one to find out how
they did it. I could dig out the part number if anyone is interested.

John

Neat idea, but stability of the output stage quiescent current and
power dissipation might be an issue.

Sure. Do it all right.

Also, need some way of closing the loop back to the op map, so
another opto isolator ?...

Do you need isolation?

Chris

That is exactly what they did.
Two optical cavities, each containing an LED and two matched photodiodes.
One photodiode in each cavity provides feedback to the driver op-amp and
the other photodiode is on the other side of the isolation barrier.
One optical cavity for positive signals and the other cavity for negative.
The overall result was reasonably good dc stability and linearity.
Bandwidth was several kilohertz. I once combined these with audio
transformers to make a multi-channel medical isolator with a linear
phase response from dc to well beyond 20kHz. Probably around 50kHz.

I\'ve also used lower voltage optoisolators with power mosfets in a
totem pole. You can cascode into depletion fets.

There\'s a logic version too:

https://www.dropbox.com/s/cr5pdtk0s9gilee/Opto_Totem.JPG?raw=1




--

John Larkin Highland Technology, Inc trk

The cork popped merrily, and Lord Peter rose to his feet.
\"Bunter\", he said, \"I give you a toast. The triumph of Instinct over Reason\"

 

[whit3rd]

On Monday, September 7, 2020 at 9:41:23 AM UTC-7, John Larkin wrote:

On Mon, 7 Sep 2020 09:17:08 -0700 (PDT), jrwalliker@gmail.com wrote:

On Monday, 7 September 2020 14:49:20 UTC+1, Chris wrote:

Also, need some way of closing the loop back to the op map, so
another opto isolator ?...

Two optical cavities, each containing an LED and two matched photodiodes.
One photodiode in each cavity provides feedback to the driver op-amp and
the other photodiode is on the other side of the isolation barrier.

I\'ve also used lower voltage optoisolators with power mosfets in a
totem pole. You can cascode into depletion fets.

Cascoding into a bipolar emitter is better for the bandpass.