Differential amplifier with amplification...

[sonnic...@gmail.com]

Hi

I need to measure a load on 14V line, using say 10 (or 100) milli-ohm resistor.
I want to get an output like 0-4V for 0-4A load. A small offset of 1V is acceptable. Even 0-2 or 1-3 or 0-8V for the load is acceptable.

I have an op-amp working on 12V.

I have been calculating on a differential amplifier. I am limited, that I need to divide the 14V to at maximum 11V or even 10 to be within working limits of the op-amp. Say 100K and 270K will do that, which limits me in amplification to ~27.

I can add an amplified after the differential amplifier but is there a better option?

 

[John Larkin]

On Mon, 19 Jun 2023 01:36:57 -0700 (PDT), \"sonnic...@gmail.com\"
<sonnichjensen@gmail.com> wrote:

Hi

I need to measure a load on 14V line, using say 10 (or 100) milli-ohm resistor.
I want to get an output like 0-4V for 0-4A load. A small offset of 1V is acceptable. Even 0-2 or 1-3 or 0-8V for the load is acceptable.

I have an op-amp working on 12V.

I have been calculating on a differential amplifier. I am limited, that I need to divide the 14V to at maximum 11V or even 10 to be within working limits of the op-amp. Say 100K and 270K will do that, which limits me in amplification to ~27.

I can add an amplified after the differential amplifier but is there a better option?

INA281A3 is cool. Hang it across a shunt resistor. It has a huge
common-mode range, -4 to +110 volts.

It would be tough to make a diffamp that good.

 

[Lasse Langwadt Christensen]

mandag den 19. juni 2023 kl. 10.37.02 UTC+2 skrev sonnic...@gmail.com:

Hi

I need to measure a load on 14V line, using say 10 (or 100) milli-ohm resistor.
I want to get an output like 0-4V for 0-4A load. A small offset of 1V is acceptable. Even 0-2 or 1-3 or 0-8V for the load is acceptable.

I have an op-amp working on 12V.

I have been calculating on a differential amplifier. I am limited, that I need to divide the 14V to at maximum 11V or even 10 to be within working limits of the op-amp. Say 100K and 270K will do that, which limits me in amplification to ~27.

I can add an amplified after the differential amplifier but is there a better option?

https://www.digikey.dk/da/products/detail/adafruit-industries-llc/1164/6565386

 

[Fred Bloggs]

On Monday, June 19, 2023 at 4:37:02 AM UTC-4, sonnic...@gmail.com wrote:

Hi

I need to measure a load on 14V line, using say 10 (or 100) milli-ohm resistor.
I want to get an output like 0-4V for 0-4A load. A small offset of 1V is acceptable. Even 0-2 or 1-3 or 0-8V for the load is acceptable.

I have an op-amp working on 12V.

I have been calculating on a differential amplifier. I am limited, that I need to divide the 14V to at maximum 11V or even 10 to be within working limits of the op-amp. Say 100K and 270K will do that, which limits me in amplification to ~27.

I can add an amplified after the differential amplifier but is there a better option?

Do a search on high side current monitor.