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Current Sense Amplifier Proposal

Other Parts Discussed in Thread: INA210, INA301

Hi Team,

I got an inquiry from one of my customers on what would be the best current sense solution for their application below:

I need some assistance in determining the error of my current sense circuit (resistor + amplifier + ADC).  My requirement is +/-2000ppm/degC (Stability at 25degC) and 100ppm/degC for the entire operating temperature for 250A of current. The 250A will be provided by multiple PSUs and each PSU has its own amplifier and sensing to regulate the current.  The BW for the CSA >360kHz.

 I wish to determine which Current Sense IC will fit this requirement, the sensing will be low side so the Vcm would have to start from 0 or a little negative.

Do let me know if there are any other requirements that you may need to find the best part to propose :) 

Thanks! 

Best Regards,

Alfred

  • Hi Alfred,

    Do we have any more information on the customer's system? From the excerpt you've attached, it would seem the customer currently has an ADC, resistor, and Amplifier selected, and are just looking to minimize the error. Can we get those part numbers? It would help to know some specifics to the system to help them combat the error they are seeing. Also, could we find out what type/size of resistor they are using and what their tolerable error for the system is? Also, from this, it seems they need to implement multiple sensors, so could we by chance obtain a schematic indicating where they are trying to measure current?

    Finally, if they are just looking fo information on error handling in current sensing amps, I would advise them to check out videos 5-12 here: training.ti.com/getting-started-current-sense-amplifiers.

    Sincerely,

    Carolus
  • Hi Carlous, 

    Sorry for the delayed response. The customer's system is an AC/DC power supply. I attached the block diagram below (removed). 

    They are working to make their system more accurate and stable. So the CSA is currently INA210, but they need higher BW because of the loop requirements as well.  The INA210 is up to 14kHz only.  For this new system we will be using Delfino as the controller one of the 12-bit ADC channels.  There will be calibration done so the initial tolerances may be nullified.  For the Rsense no specific part yet for this version.

    Thanks!

    Best Regards,

    Alfred

  • Alfred,

    I am assuming that the ppm requirements listed by your customer are gain error and drift for their application? If so, looking at the system, as well as your requirements, I would recommend the INA301 product line. This product line has the enhanced BW capacity your customer needs for his control loop. Also, the A3 product meets the 2000ppm/degC spec, and the A1 and A2 products beat the requirement (and for all three of these cases, this is the worst case for the product). It also contains an overcurrent signal line for added protection if they wish to integrate it into their system. It is not a requirement for the part however.

    Hope this helps. Keep us posted as your process moves forward and we can provide more information as necessary.

    Carolus